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DEPARTMENT OF AGRICULTURE

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'l OF

Publication 1257 1965

RAPESEED MEAL
for LIVESTOCK and POULTRY

-A REVIEW

Prepared by

The Associate Committee on Animal Nutrition,

National Research Council of Canada

Editorial Committee

Dr. J. P. Bowland, Professor of Animal Nutrition,
University of Alberta, Edmonton, Alberta

Dr. D. R. Clandinin, Professor of Poultry Nutrition,
University of Alberta, Edmonton, Alberta

Dr. L. R. Wetter, Head, Plant Biochemistry Section,
Prairie Regional Laboratory, National Research
Council, Saskatoon, Saskatchewan

Published by

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1.5M— 32905— 12:65

CONTENTS

Page

Preface 5

Acknowledgements 6

*&'

Chapter 1 Rapeseed Botany, Production and Utilization 7

R. K. Downey

Chapter 2 Processing of Rapeseed Meal 24

C. G. Youngs

Chapter 3 The Chemical Composition of Rapeseed Meal 32

L. R. Wetter

Chapter 4 Goitrogenic Properties 45

J. M. Bell and R. J. Belzile

Chapter 5 Feeding Value of Rapeseed Meal for Ruminant Animals 61
F. Whiting

Chapter 6 Feeding Value of Rapeseed Meal for Swine 69

J. P. Bowland

Chapter 7 Feeding Value of Rapeseed Meal for Poultry 81

D. R. Clandinin

Chapter 8 Status of Rapeseed Meal as a Protein Supplement 93

A. R. Robblee

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PREFACE

Rapeseed was first grown commercially in western
Canada in 1942 as a war measure to supply oil for lubrication
of marine engines. Production has expanded rapidly so that
rapeseed now represents an important crop for Canadian
farmers. A major byproduct of oil extraction is rapeseed
meal. In recent years there has been a conversion from ex-
peller extraction of the oil to prepress-solvent or solvent
extraction. As a consequence commercial rapeseed meals are
not subjected to high temperatures during processing. Research
suggests that these meals are comparable to soybean meal as
a protein supplement for most classes of livestock and poultry.

The increased production of rapeseed, the expanding
research in breeding of new rapeseed varieties, the changes in
processing methods and increased knowledge of nutritional
properties of the meal have made it imperative that in-
formation on the nutritional value of rapeseed meal should be
compiled and evaluated under one cover. It is hoped that
this review will allow feed processors and livestock feeders
to make optimum use of rapeseed meal. The review should
also point out to research workers the areas where information
on rapeseed meal is limited.

Each chapter of this review is intended to be a complete
entity which may be read without extensive reference to previ-
ous or subsequent chapters. Therefore there is a certain
amount of overlapping to allow an individual author to deal
with the subject matter in breadth as well as depth. As in any
collaborative monograph, helpful suggestions, ideas and criti-
cisms have been made by numerous people. The editors and
authors wish to acknowledge, with thanks, their indebtedness
to these unnamed collaborators.

Edmonton, Alberta, Canada
May 15, 1965

John P. Bowland, Chairman
Editorial Committee

ACKNOWLEDGEMENTS

The Editorial Committee wishes to acknowledge, with
sincere thanks, the contributions of those who wrote the
individual chapters of this monograph. The original suggestion
that such a monograph be prepared was made at the 1963
meeting of the Associate Committee on Animal Nutrition of
the National Research Council of Canada. The continuing sup-
port of this Associate Committee is gratefully acknowledged.
Publication of the monograph would not have been possible
without the financial assistance of the Canada Department of
Agriculture. Financial support was also contributed by Co-
operative Vegetable Oils, Altona, Manitoba; Vegetable Oil
Division, Saskatchewan Wheat Pool, Saskatoon, Saskatchewan
and Western Canadian Seed Processors Limited, Lethbridge,
Alberta.

CHAPTER 1. RAPESEED BOTANY, PRODUCTION
AND UTILIZATION

R. K. Downey, Research Scientist
Research Station, Canada Agriculture, Saskatoon

Botany
Origin

The origin and history of Brassica napus L. and Brassica campestris
L. is not well documented, although closely related species were well
known in ancient times. Black mustard, Brassica nigra L., was referred
to by early Greek writers and was cultivated in Europe in the thirteenth
century (137). Cabbage and kale (Brassica oleracea L.) were used by the
Greeks and Romans before the Christian era (23). The English word
rape, as it applies to the oilseed forms of B. napus and B. campestris, is
derived from the Latin word rapum, meaning turnip. Plants of B. napus
L. var. oleifera are called rape, colza and raps in Europe, and Argentine
rape in Canada. In Europe, B. campestris L. var. oleifera is known as
turnip rape, navette and rubsen, whereas in Canada it is called Polish
rape. In this chapter the European common names of rape and turnip
rape are used, and refer specifically to oilseed forms of B. napus and B.
campestris, respectively. Collectively the two species are referred to as
"rapes" or "rapeseed". The earliest direct references to the oilseed rapes
are found in ancient Indian Sanskrit writings of 2000 to 1500 B.C. (121).
Singh (121) considered the Indian B. campestris variety Yellow Sarson
to be the oldest of the various rapes and mustards found in that Asiatic
subcontinent.

The wide commercial distribution of B. campestris as a weedseed and
vegetable has tended to obscure its center of origin. Sinskaia (123), after
a study of the diversity of forms found within this species in Europe and
Asia, suggested that the center of origin of both turnip and turnip rape
would ultimately be located in Asia. On the other hand, she noted that all
cultivated Asian turnip rape is of the summer form, and thus concluded that
winter turnip rape must have originated under a maritime climate such
as the Mediterranean. In contrast, Andersson and Olsson (6) recognized
three main geographical groups: Asiatic, Mediterranean and West Euro-
pean. Certainly the Indian Sarson varieties are distinct from the European
forms (90, 121, 127, 128). Probably the Indian and European varieties
were separated at an early stage in the development of the species and
evolved along different lines.

B. napus was thought to have its origin in the Mediterranean area
(123). However, this theory was formed before the genome constitution
of B. napus was known. It is now known that B. napus is an amphidiploid
resulting from crosses between plants of B. campestris and B. oleracea
(135). Thus, B. napus has probably originated at many different times and
locations where plants of the two basic species grew in proximity (90) .

Domestication

Domestication of rape and turnip rape has occurred whenever the
economic value of the locally adapted weed was recognized (123). In
Europe, cultivation of rape and turnip rape on a field scale was not
common until the thirteenth century. However, even before this time,
seed was gathered from wild forms and the oil extracted and used for
illumination and soap making. Field cultivation appeared first in Belgium
and from there spread to Holland and North Germany and, in the sixteenth
century, to South Germany. Apparently both species were grown since
seed of both types has been found in grist mills of old German settle-
ments (12). In the nineteenth century the cultivation of rapeseed ex-
tended eastward into Switzerland, Poland and Russia, and northward into
Denmark and Sweden (12, 146). At this time, approximately 3,000 to 4,000
hectares (1 hectare=2.471 acres) of rape were grown in Sweden (3), and in
1866, 15,500 hectares in Denmark (69). In India the ancient custom of
sowing summer turnip rape called Sarson and Toria and the Indian mustard,
Rai, in mixture with other crops such as wheat, barley and gram, is still
practiced as a protection against total crop failure (121). The history
of rapeseed cultivation in China is obscure. Old Japanese literature indi-
cates that rape was introduced to Japan 2,000 years ago directly from
China or through the Korean Peninsula. Oriental forms of B. campestris,
indigenous to Japan, were used as vegetables as early as the sixth century
but not until the fourteenth century was the seed pressed for lamp oil.
In the seventeenth century the Portuguese and Spanish traders introduced
fried foods to the Japanese. In this way rapeseed oil was established as
the traditional edible oil of Japan (59, 74). North and South America
adopted oilseed rape as a cultivated crop prior to and during World
War II.

Taxonomy and Genome Relationships

The Cruciferae family to which the genus Brassica belongs, con-
tains many important crop plants and weeds (Table 1.1). In the domesti-
cation of the Brassica genus man has utilized and modified through selec-
tion almost every plant part. The occurrence of similar forms in more
than one Brassica species resulted in considerable misclassification by early
botanists as they separated species solely on morphological characters.
Thomas and Crane (130) noted that it was less confusing, in Brassica,

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to use common than Latin names. However, in recent years there has
been general agreement on the nomenclature of major groups, although
opinions are still divided on the B. campestris complex (91, 127, 128, 143).
The genetic and cytological relationship between the two rape species
and their close relatives was established by Morinaga (77, 78, 79, 80, 81,
82), Sasaoka (115), and U (135). They made interspecific crosses and
analyzed cytologically chromosome conjugation at metaphase I. Morinaga
(82) proposed that the species of B. napus, B. jancea and B. carinata, which
have higher chromosome complements, were amphidiploids derived from
the monogenomic species B. nigra, B. campestris and B. oleracea. The
accuracy of this scheme was corroborated by the synthesis of existing
species. Fertile plants of B. napus were formed from crosses between
B. campestris and B. oleracea (57, 64, 68, 89, 95, 98, 111, 112, 135). Simi-
larly, plants of B. juncea were formed from crosses between B. campestris
and B. nigra (56, 72, 93, 107) , and plants of B. carinata from crosses be-
tween B. oleracea and B. nigra (57, 73, 75) . There also is cytological evi-
dence that the three elemental genomes are themselves secondary poly-
ploids, probably originating from a common ancestor with a basic
chromosome number of 5 or 6 (2, 29, 30, 60, 72, 109, 110, 120). The genera
Sinapis, Eruca and Raphanus also may have evolved from this same
progenitor (58, 60, 72).

Morphology

Annual and biennial forms of both species are cultivated. B. napus
and the Yellow Sarson variety of B. campestris are largely self-fertile.
Other B. campestris varieties are self-incompatible. Under field conditions
the rapes are cross-pollinated by wind and insects (94). Seeds mature 30
to 40 days after fertilization. The seed is primarily embryo, surrounded by
a thin layer of endosperm. The cotyledons are conduplicate and contain
30 to over 50% oil. Most of the seed oil is laid down in the last 20 days of
maturation (5, 76, 104, 122). The thin seed coat may be black to reddish
brown or yellow and its reticulations are used for species identification
(20, 84).

Adaptation

The rapes are adapted to temperate regions and also to subtropical
areas of India, Japan and Mexico where they are used as winter or cool
season crops. Wild forms of B. campestris are found from the British
Isles east to Japan and from northern Norway south to the Sahara,
Pakistan and the northern provinces of India (123). In more recent times,
distribution has been extended to North and South America, Australia and
New Zealand. In contrast, B. napus is not cultivated in central Asia
(121, 123) and the northern dispersion is more restricted in Sweden and
Canada (51, 69). Schwarze (117) in Germany states that high temperatures

during ripening favor high oil content in rape, provided there is sufficient
moisture. In Canada, however, higher oil contents are obtained in more
northerly latitudes (22). ruder controlled moisture and day length Siemens
(119) found significantly higher oil content in B. napus seed matured under
12.7 C day temperature than under 18.3 or 23.9 C. Highest yields of seed
are obtained on deep, well-drained, loamy soils (6, 121). However, rape is a
recommended crop for saline areas in Holland (1, 102) and peaty soils in
Sweden and Canada (51, 69). Thus, crop adaptation is extensive and
production depends more on the relative availability and cost of other
vegetable oils than on soil and climatic conditions.

Types and Varieties

Of the two species, B. napus has a greater potential yield of seed
and oil than B. campestris. Where winter forms can be grown they are
more productive than the summer types (3, 51, 69).

In Europe, three basic groups of winter rape are found. The Janetzke
variety is intermediate between the hardy and non-productive East
European group and the moderately hardy but high-yielding mid-European
types. Lembke's winter rape, from wrhich the improved varieties of Matador,
Vestial, Alsace and Oleor have been bred, is characteristic of the mid-
European group. The nonhardy West European group is represented by
Mansholt's Hamburger (6).

Winter turnip rape is grown primarily in Finland, middle Sweden,
and Eastern Europe where greater hardiness is essential. In B. campestris,
as with B. napns, hardy material is found in Eastern Europe, but poten-
tially higher yielding germ plasm of moderate hardiness originates in
Middle Europe. Such varieties as Duro, Gruber and Janetzke are inter-
mediate between the moderately hardy Lembke and the hardy Rapido
winter turnip rape varieties (6). Regina II, Janetzke and Cresus varieties
of summer rape are used in Europe as alternate crops when winter seedings
fail or where winter forms will not survive. Where the summer growing
season is short, the summer turnip rape varieties Arlo and Bele are
important.

In the Western Hemisphere, Chile grows both Matador winter rape
and Regina II summer rape (103). In Canada, only the summer forms
are grown for seed, as even the most winter hardy turnip rape varieties will
not consistently survive on the open plains of western Canada. The turnip
rape varieties Arlo and Echo occupy 70 to 80% of the rapeseed acreage of
western Canada. Although they have only 80 to 85% of the yield poten-
tial of the Canadian B. napus varieties, Nugget, Tanka and Golden, they
are preferred because of their 10- to 14-day earlier maturity (51, 114).

Production in Japan, as in Europe, is almost exclusively of winter rape.
Widely grown varieties such as Norin1 No. 6, 14 and 17, were bred from

' Norm stands for Agriculture-Forestry.

B. napus material, but other important varieties such as Michinoku- and
Murasaki-natane2 were derived from B. napus X B. campestris crosses
(67,83,118).

In central Asia, annual B. campestris forms such as Toria and Sarson
are grown exclusively. In China, Pakistan and India little distinction is
made between these turnip rape forms and B. juncea as all are grown
for their oil (32). There are marked contrasts in growth habit, seed size
and color, pod size and shape, and oil composition between European
turnip rape and the Asian group (91, 121). Within the Asian group the
main difference between Toria and Sarson is in maturity, with Toria being
early. Improved Indian varieties include Yellow Sarson No. 151, 10, 40 and
13; Brown Sarson BSG; and Toria No. 7, 9 and Abhar (101, 121).

Production

Among the edible vegetable oils, rapeseed ranks fifth in total world
tonnage, being exceeded by soybeans, peanuts, cottonseed and sunflowers.
China, India and Pakistan produce about two-thirds of the world's rape-
seed (Table 1.2). Chinese production, primarily centered in the Yangtze
Valley, has been markedly lower in recent years. However, domestic
demand in Asian countries usually exceeds supply and thus their production
has little effect on the world vegetable oil price structure (62).

Rape and sunflowers are the only edible vegetable oil crops that can
be produced effectively in northern parts of Europe, Asia and Canada.
Major production shifts have occurred in Europe and the Americas since
World War II. Increased production in Poland, Sweden and Finland
resulted at least partially from the political need to be self-sufficient in
vegetable oils in case of war (3, 113). Most European countries control
production through a guaranteed price or by regulating the amount of
rapeseed oil that must be used in edible products. In Canada, economics
alone resulted in the establishment of a rapeseed industry following World
War II since rapeseed proved to be an alternate crop to spring wheat in
northern regions of the Canadian prairies.

In most countries domestic rapeseed consumption exceeds production.
Only one-ninth of world production enters export channels (136). In recent
years Canada has exported more rapeseed than all other countries combined.
Japan, Italy, Netherlands, Algeria, France and West Germany have been
the main customers. French exports have been principally to Algeria and
Italy, while seed from Denmark and Sweden has gone to Italy, France
and Algeria. Sweden and France are the largest exporters of rapeseed oil,
with West Germany, Italy and United States the most consistent importers
(32) . Accurate statistics of trade in rapeseed meal are not readily available.
However, it has been estimated that the major producing countries have
had annual exports of approximately 30,000 metric tons of meal in the
period 1958 to 1962 (31).

2Natane stands for rapeseed.

Table 1.2. World production of rapeseed 1930-39; 1945-59; 1962; and
the average exports of rapeseed and oil, 1958-62 (32)

Exports,

Country

Production, 000 metric tons*

000 metric tons

1958-62

1930-34

1935-39

1945-49

1950-54

1955-59

1962

Seed

Oil

Asia

China

2,227

2,102

(3,100)

(2,854)

(933)

(935)

7.5

Formosa

—

Indiaf {
Pakistanf )

1,264

969

1,001

866

956

1,259

—

0.2

277

312

355

—

Japan

118

210

272

329

—

0.1

Turke}'

—

Europe

Austria

—

Belgium

—

Bulgaria

(3)

—

Czechoslovakia

—

(29)

—

Denmark

—

0.1

Finland

—

France

135

130

153

12.1

German}-, West

I "

104

112

—

4.8

Germany, East

243

166

159

—

0.4

Hungary

(2)

—

Italy

—

Netherlands

—

0.8

Poland

(48)

(95)

105

349

—

Romania

(5)

—

Sweden

—

152

139

126

10.1

Switzerland

—

Yugoslavia

—

Africa

Ethiopia and

Eritrea

—

Western Hemisphere

Argentina

—

Canada

—

121

129

0.3

Chile

—

Mexico

—

(7)

—

United States

—

•Figures in parentheses are estimates only. Annual production of 18,000 metric tons has been reported for the
U.S.S.R. for 1935-39 (54), but recent data on Russian production and acreage are not available,
tlncludes rape and mustard.

Utilization
Forage Crop

Rape produces an abundance of succulent fodder (66). Some winter
and spring rape varieties are used as fodder crops for cattle throughout
Europe. In Swedish yield trials, Garton's Early Giant winter rape pro-
duced an average dry matter yield of 5,925 kg per hectare (5,273 lb per
acre), of which 14.9% was crude protein and 18.6% crude fiber (96).
In Britain, kale {B. oleracea var. acephala) and rape (B. napus) are the
main sources of fall and winter fodder (40). A cross of B. campestris X B.
oleracea resulted in an excellent fodder crop for Japan (65, 141), and B.
campestris varieties are used for fodder in India (121). Forage rape is the
most important green fodder crop in New Zealand for fattening lambs
(85). In North America, forage rape is used primarily as a hog pasture
and produces rapid, economical gains (44).

Oilseed Crop

Meal. — Rapeseed crushed in modern mills yields approximately 40%,
oil and 50% oil meal or oil cake, the remainder being moisture. The major
use of the oil meal is as a high protein feedstuff which will be discussed in fol-
lowing chapters. However, in Japan the major meal use is as a high nitrogen
fertilizer for over 8,000 hectares (19,284 acres) of tobacco. At least
one-half the 100 to 150 kg per hectare (89 to 134 lb per acre) of nitrogen
required by Japanese tobacco is supplied through the application of 800
to 1,250 kg of meal per hectare (712 to 1,112 lb per acre). The balance
of the nitrogen is usually supplied as urea or ammonium phosphate in
compound fertilizers, although some growers continue to use rapeseed meal
exclusively (129, 142). Rapeseed meal fertilization is considered indis-
pensable to production of high-quality tobacco in high rainfall districts
since the slow nitrogen release from the meal corresponds to the uptake
requirements of tobacco and reduces nitrogen losses due to leaching (142).
Low-quality meals and meals containing appreciable amounts of mustard
are also used as a general purpose fertilizer in Europe and India.

Oil. — Chemical composition: Crude rapeseed oil consists primarily
of fatty acid glycerides, together with minor components such as the free
fatty acids, chlorophylls, phosphatides and sterols. The minor constituents
are removed on refining, bleaching, and deodorizing, but have an important
bearing on the color and keeping qualities of the crude oil. When chloro-
phylls are present in large quantity they may be difficult to remove.
The amounts of minor constituents depend primarily on conditions during
seed development, harvest and handling. Tocopherols, important as anti-
oxidants and as a vitamin E source, are also found in the oil, but the factors
influencing the amounts have not been intensively studied (8).

The fatty acid composition of a vegetable oil determines its suitability
for industrial or edible purposes. However, the refractive index and iodine
number of rapeseed oil is not a reliable index of the fatty acids present.

Craig and Wetter (38) report two rapeseed samples with iodine numbers
of 104.6 and 104.1 which contained 40.4 and 22.4% erucic acid, respec-
tively. This apparent anomaly results from the variation in degree of un-
saturation and carbon chain length found in the oil of both species (Table
1.3). Extreme erucic acid values of 57 to 61% have been reported in the
Indian Sarson varieties (48, 63, 121). Singh (121) reports only 1%
linolenic acid in these Indian varieties. However, similar seed analyzed
by gas chromatography in our laboratory contained 8 to 9% linolenic
acid 1 48). In its present composition rapeseed oil is a dual-purpose oil.
The high percentage of oleic and erucic acids gives it important industrial
uses, while the relatively low content of linolenic acid makes it suitable
as an edible oil.

Industrial uses: In early times rapeseed oil was used primarily for
illumination and soap making. As the demand for products for these
uses decreased, marine engines were developed which required a lubricant
that would cling to metal surfaces when washed by steam and water.
Blends of both refined and blown rapeseed oil proved superior to mineral
oil for this purpose. In recent years, a general purpose grease has been
developed in which rapeseed oil replaces castor oil. This grease is now
marketed in Canada (55, 86, 99). The oil is also used in conjunction with
tallow as a lubricant for cold rolling steel (21, 138) and in the manufac-
ture of soft soap used in sizing cloth (121). The erucic acid fraction has
special industrial applications such as the lubrication of jet engines, the
manufacture of plastics, the making of erucic ethylene glycol polyester
surface film to reduce evaporation from rice paddies, and as a flotation
agent in potash mining.

Edible uses: Most of the oil produced today is used for salad and
cooking oils, margarine, and shortenings. Thus nutritional aspects of rape-
seed oil have been extensively investigated. Among digestibility coefficients

Table 1.3. Ranges, in percentages, of fatty acids in B. napus
and B. campestris (8, 10, 35, 48, 54, 62a, 71 144)

Percent composition

Fatty acid*

Symbol

B. napus

campestris

Palmitic

C16:0

2-4

2 - 3

Stearic

C18:0

1 - 2

Oleic

C18:1

9 - 24

14 - 26

Linolcic

C18:2

13 - 16

12 - 18

Linolenic

C18:3

5-12

7-12

Eicosanoic

C20:l

7-15

8-12

Krucic

C22:l

36 - 54

22 - 46

"Minor amounts (1% or less) of palmitoleic, aracliidic, and doeosadienoic are also
present.

reported are 98 to 99% for man (43) and 77% for rats (42) (see
Chapters 5, 6 and 7 for further information on digestibility). It is generally
agreed that, when rapeseed oil makes up a substantial portion of the
diet of the rat, food intake is reduced, growth is retarded, and life
extended (19, 131, 132, 133). These effects have been attributed to
erucic acid in the oil, but recent studies indicate that the low content
of saturated acids, especially palmitic acid, may be the cause (14, 39).
The effects of rapeseed oil and erucic acid on the adrenals and fertility of
the rat have also been studied. It is now apparent that strains of
rats differ in their reaction to diets containing rapeseed oil. The rats
used by Carroll (24, 25, 27, 28, 87) exhibited reduced fertility and increased
cholesterol level and size of the adrenals. However, the strain used by
Beare (13, 15, 16, 17, 18, 19) reproduced normally and showed no effects
on the absolute adrenal weight or proportion of adrenal weight to body
weight when on rapeseed oil diets. In addition, when fed to rabbits, guinea
pigs, chickens and dogs rapeseed oil had little or no effect on adrenal
cholesterol (26). Wigand (140) reported that serum cholesterol levels
in rabbits were reduced equally by rapeseed and corn oils.

Prospects of Crop Improvement

The opportunity for improvement of any agricultural crop is dependent
on the genetic variation which exists within the crop and its close relatives,
as well as the facility with which desirable characters can be recognized
and fixed in the population. The variability evident in species of rape
and throughout the Brassica genus, coupled with the ease with which the
species may be crossed, suggests that there are great possibilities for
improvement.

Breeding for Increased Seed and Oil Yield

The common aim of world rapeseed breeding programs is the develop-
ment of strains that produce higher yields of seed with higher oil and
protein contents. Numerous varieties have been selected from adapted sorts
in recent years. However, little attention has been given to commercial
hybrid seed, even though pollen-sterile individuals have been identified
(6, 45, 68). Similarly, the use of X-irradiation as a breeding tool has
not been extensive despite the success of Regina II summer rape which
was selected from an irradiated population (4) . Crosses between ecotypes
and species have also been successful and hold considerable promise (6,
83, 90).

Polyploid breeding in oilseed rape and turnip rape has not been
fruitful (96). Although tetraploid turnip rape plants were larger and more
vigorous than the diploids, they were lower in fertility, seed yield and oil
content (9, 106, 116). Despite intensive selection for seed and oil yield,
tetraploid turnip rapes have not equalled the diploid varieties (50, 70,
100, 105).

Increased oil content in rapeseed results in a greater margin of profit
to the crusher (88). Oil content varies widely with year, location, maturity
at harvest, soil fertility and variety. Despite this, the heritability of this
character, based on parent-progeny regressions, is considerably higher than
for seed yield (6, 92). Thus selection for oil content has been very worth-
while, both in Sweden (97) and Canada where increases of 1.3 to 4.0%
in oil have been obtained in recent years (47). Unfortunately a high nega-
tive correlation exists between oil and protein content (126), and between
oil content and seed size (92) . The association is not complete however.
Olsson (92) combined high oil and large seed by crossing summer and
winter rape and, in Canada, the summer rape variety Tanka produces larger
seeds which contain more oil and protein than seed of the Golden variety
from which it was selected.

It would appear that the limiting factor in increasing oil content
has been the number of samples that could be analyzed since percent-
age oil and seed yield are not correlated (92, 126). Recent developments
of oil determination techniques, which can be applied to seed lots of less
than 5 g will greatly facilitate selection work (33, 134). In particular,
the adaptation to oilseed work of nuclear magnetic resonance (11, 34) and
air pyenometer equipment (145), whereby small seed lots retain their
viability during rapid analysis, provides the plant breeder with powerful
tools.

Breeding for Oil Quality

Oil quality is an important characteristic as rapeseed oil competes
directly with other oil crops on the vegetable oil market. Gas chromatog-
raphy has given the plant breeder rapid and accurate means of meas-
uring oil quality (36, 37, 53). Wide variation in fatty acid composition
is present within and between species (8, 38, 48, 49, 124, 125) , but sufficient
information is not available from industry and nutritional studies to
predict accurately the ideal fatty acid composition. However, for human
consumption, as well as improved keeping qualities and extended versa-
tility of the oil. it would appear desirable to reduce erucic, eicosanoic, and
linolenic acids to zero, and at the same time raise the level of linoleic
acid while retaining the low content of saturated acids. Alternatively, since
erucic acid has important industrial uses this component could be maxi-
mized in some varieties.

Considerable progress towards producing both types of oil has been
made in Canada (48, 49, 125). Further, the biosynthetic pathway (52) and
genetic control of erucic and eicosanoic acids synthesis has been determined
(46, 53, 61, 124). Breeding material now under investigation, in lines con-
taining no erucic acid, indicates the existence of genotypes that produce
lower amounts of linolenic acid and greater amounts of linoleic acid
(Table 1.4).

97386—2

Table 1.4. Fatty acid composition of improved oil selections in comparison
with present varieties Golden and Arlo (48)*

Species and variety

Fatty acids, percent

C16:0

C18:0

C18:l

C18:2

C18:3

C20:l

C22:l

B. napus
Golden

3.3

1.1

18.6

14.0

7.8

13.4

41.8

Nugget

3.3

1.5

22.8

12.2

5.4

14.2

40.6

Zero erucic

4.7

1.8

63.8

20.0

8.9

1.3

0.0

B. campestris
Arlo

3.2

1.1

26.6

17.5

8.8

11.8

31.0

Yellow Sarson

1.8

0.8

11.7

10.5

. 8.3

5.9

61.0

Zero erucic

4.3

0.1

54.8

31.1

9.7

0.0

*Major changes in fatty acid composition in italics.

Breeding for Meal Quality

In some countries, limitations are imposed on the feeding of rapeseed
meal to certain classes of livestock. These limitations stem from the
presence of low molecular sulfur compounds in the seed, some of which
may, when released through enzyme action, cause metabolic disturbances
in the animal. The nature and possible effects of these isothiocyanate and
oxazolidinethione compounds will be discussed in detail in the following
chapters. The problem they present may be eliminated either through
modified processing methods or by plant breeding. In Canada, a new
processing method which destroys the enzyme myrosinase by cooking the
crushed seed without addition of water has become available (108). The
safest and most economical solution, however, is either to breed strains
with little or no sulfur-containing glucosides in the seed, or to select lines
which produce only harmless isothiocyanates upon glucoside enzyme hydro-
lysis. Unfortunately, little is known of the relative toxicity of the various
isothiocyanates found in the Brassica genus. On the other hand, present
studies indicate that it is possible to select for both quantity and type
of isothiocyanates from variation that exists within and between species
(7,41, 139).

Unpublished data from the National Research Council and the Canada
Agriculture Research Station at Saskatoon show that sulfur fertilization has
a marked effect on the total content of these compounds in the seed, but
that, regardless of the level of sulfur applied, some rape varieties are

consistently lower in total isothiocyanates. It also has been determined
that seed of Yellow Sarson differs markedly from the Canadian B.
campestris varieties in the type of isothiocyanates it contains, and that
tin1 isothiocyanates present and their ratio to one another are entirely
dependent on the genotype of the maternal parent. Thus, since both the
total amount and kind of compounds are largely under genetic control,,
breeding for meal quality improvement is feasible, provided an accurate
and rapid means of quantitative and qualitative analysis is developed.

Summary

Oilseed rape {Brassica napus L. ssp. oleifera) and turnip rape (B.
campestris L. ssp. oleifera) of the Cruciferae family are closely related to
one another, to the mustards (B. juncea, B. nigra and B. carinata) and to
cabbage and kale (B. oleracea) . Indeed, B. napus is an amphidiploid re-
sulting from crosses between plants of B. campestris and B. oleracea.

Domestication of rape and turnip rape appears to have occurred
wherever the value of the seed oil was recognized. Rapeseed is adapted to
temperate regions and as a cool season crop in subtropical areas. Only
annual forms are grown in Central Asia and Canada, but in other countries
both annual and biennial forms are cultivated. B. napus has a higher seed
yield potential than B. campestris but B. campestris has a greater range
of adaptation.

World rapeseed production is about four million metric tons annually,
of which approximately 75% is produced and consumed in Asia. Rapeseed
stands fifth in total world production among edible vegetable oils. Canada
exports more rapeseed than all other countries combined. Sweden and France
are the main exporters of rapeseed oil. Extraction in modern mills gives
40% oil and 50% oilmeal, the remainder being moisture. Most of the oil
is used in edible products, such as margarine and shortenings, and salad
and cooking oils. The oil also has widespread industrial uses. The meal is
mainly used as a high protein feedstuff, although in Japan the primary use
is as a fertilizer for tobacco. Some varieties of rape are important as fodder
crops in Europe, New Zealand and to a lesser extent in North America.

Prospects for overall improvement are great. Significant increases in
seed and oil yields have been made in recent years and new oil composition
types have been selected. New processing methods have improved the
quality of rapeseed meal and recent research indicates that the meal may
be improved further through plant breeding. Rapid advances can be
expected as new analytical and chemical techniques are applied to the
extensive variation found within the rape species and their close relatives.

97386— 2i

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Transl. by P. S. Hudson. Commonwealth Agr. Bur. (Great Brit,).

CHAPTER 2. PROCESSING OF RAPESEED MEAL

C. G. Youngs, Senior Research Officer
Prairie Regional Laboratory, National Research Council, Saskatoon

Introduction

The processing of rapeseed to obtain oil and meal is similar to
that for other high oil content seeds, such as linseed. In fact, the initial
processing of rapeseed in Canada was done in plants designed for the
processing of flax. These were expeller pressing mills and since the oil was
the more valuable product they were operated to obtain a maximum oil
yield. This involved the use of high pressures and resulting high tem-
peratures. The major market for the oil at that time was an industrial oil
and the type of processing used did not materially affect the quality of
the oil for this purpose. It did, however, have an adverse effect on the
quality of the meal obtained. As the demand for the oil for industrial
purposes decreased and interest in it as an edible oil increased, attention
was turned to the effect of processing on the quality of oil for this purpose.
Pressures and temperatures in the expellers were lowered and, although
this meant leaving more oil in the meal, the quality of both the oil and the
meal was improved. As it became evident that an expanding market ex-
isted for rapeseed oil as an edible oil a number of new processing plants
were constructed. These all involved solvent extraction of the oil from
the seed either directly or after a mild expeller press to remove a portion
of the oil. The use of solvent extraction allows almost complete removal
of the oil from the meal but under mild conditions to provide the
quality desired in the products. This type of processing has supplanted
the earlier expeller processing.

The purpose of this chapter is to describe briefly the various processes
which are, or have been, used and the effect of these on the quality of rape-
seed meal.

Types of Processing
Expeller Pressing

This is a mechanical process in which the oil is squeezed from the
seed. Prior to pressing the seed is crushed in roller mills as the first step
in breaking up the seed structure to allow a separation of the oil and
meal. Many oil-bearing cells remain intact after crushing and the walls
of these cells are made permeable to oil by the action of heat and moisture
in the next step which is cooking. Cooking is usually carried out in

"stack cookers''. These consist of a series of superimposed cylindrical
steel kettles independently jacketed for steam heating. The crushed seed
is agitated by a sweep-type stirrer in each kettle. Automatically operated
gates provide a continuous progression of the seed down through the
kettles. The top kettle is provided with spray jets for the addition of
moisture and each of the lower kettles is provided with an exhaust pipe for
removal of moisture. Normally oil seeds are moistened in the early stages
of cooking and their moisture content reduced during cooking. For rapeseed
the resident time in the cooker is approximately 30 min and the maximum
temperature reached varies from 100 to 120 C (212 to 248 F).

The crushed, cooked seed then passes to the expeller or screw press.
This is essentially a continuous cage press in which the pressure is de-
veloped by a rotating worm shaft. Extremely high pressures, in the order
of 15,000 to 20,000 lb/inch2 (1050 to 1400 kg/cm2) can be built up in the
cage or barrel through the action of the worm working against an adjust-
able pressure orifice or choke that constricts the discharge of cake from
the end of the barrel. The interior of the barrel is made up of flat
steel bars set edgewise around the periphery and spaced to allow the oil to
flow between the bars while the cake is contained within the barrel.

The action of the worm in the barrel of the expeller generates not
only pressure, but also heat. The barrel is, therefore, cooled either by
circulating water through channels in the barrel or by cooling the expressed
oil and flushing a portion of this back over the exterior of the barrel.
In a well-operated expeller plant the oil content of the cake can be reduced
to about 4%, but may range up to 6 or 7 percent. The cake issuing from the
expeller is both hot and dry and water may be sprinkled on it at this
point to reduce the temperature and increase the moisture. The cake is
then ground and is ready for marketing.

Prepress plus Solvent Extraction

In this process a portion of the oil is removed from the seed by
pressing with expellers and the remaining oil is then extracted with an
organic solvent. The prctreatment of the seed and the expellers used for
pressing are the same as described in the previous section. In this case,
however, only 70 to 80% of the oil is removed by pressing. This requires
much less pressure than when oil recoveries of over 90% are required
in straight expeller pressing. As a result of the lower pressures much less
heat is generated in the expeller barrels and the throughput of the ex-
pellers is greatly increased.

The cake from the expeller, containing 15 to 20% oil, is reground
and conveyed to the solvent extraction section of the plant. By far the
most common solvent used is a light petroleum fraction composed largely
of normal hexane with a boiling range of 60 to 70 C (140 to 158 F).
The object in solvent extraction is to remove as much of the oil as pos-
sible from the meal with a minimum of solvent. This is accomplished most

efficiently by continuous countercurrent extraction. A number of mechanical
means have been developed for moving the seed mass and the miscella
(solvent plus oil) in opposite directions with free intermixing and for
effecting a final separation of the miscella and the marc (solvent-saturated
meal). These mechanical systems include screw conveyors in an inclined
tube or "U" tube configuration; bucket conveyors operating in a vertical
or horizontal direction; screen paddles scooping the marc from one con-
tainer to the next; and vertical baskets rotating in a horizontal plane.
The end result is the same in all cases in that the meal discharged from
the extraction unit is saturated with solvent and contains around 1%
of lipid.

The solvent is stripped from the meal in desolventizers which are
similar to the stack cookers described in the section on expeller pressing.
The bulk of the solvent is flashed from the meal in the top kettles. Live
steam is introduced in the middle kettles to remove the remaining solvent
and the meal is dried in the bottom kettles. At this stage the meal is
solvent free, contains around 1% lipid, has a moisture content of 10 to 12%
and is ready for marketing.

Direct Solvent Extraction

Normally high oil content seeds such as rapeseed are not directly
solvent extracted as they tend to disintegrate into fine particles when
placed in solvent. These fine particles cannot be handled successfully in
the usual solvent extraction equipment. Recently a process known as
"Filtration-Extraction" (8) has been developed which overcomes this
problem and, as far as is known, is the only process that has been applied
to the direct solvent extraction of rapeseed. The crushed, cooked seed is
fed continuously into a horizontal, cylindrical tank and conveyed down
its length as a slurry with miscella and slowly agitated to accomplish
maximum extraction of the oil with minimum disintegration of the meal.
The slurry is laid down on a horizontal rotating filter leaving the marc
on the pan in a layer about 5 cm thick. As the filter rotates, the cake is
washed; first with concentrated miscella to remove fines; then with two
washes of decreasing oil content miscella; and finally with pure solvent.
The marc is continuously removed and conveyed to the same type of
desolventizing equipment as described in the previous section. The meal
from the desolventizer contains about 1% lipid and 10 to 12% moisture,
as in the case of prepress plus solvent extraction, and is ready for marketing.

Effect of Processing Variables on Meal Quality

One obvious effect of the method of processing on the quality of meal
is the amount of oil left in the meal. As noted in the previous sections, in
processes involving solvent extraction the residual lipid in the meal is
reduced to 1% whereas in straight expeller-pressed meals this may vary
from 4 to 7 percent. For a meal with 40.0% protein on an oil free basis, the

protein content with 1% oil would be 39.5% and with 7% oil 37.2 percent. In
addition to this drop in percent protein the presence of 7% oil appreciably
affects the energy— protein ratio of the meal and this may be a factor in
evaluating the meal for animal nutrition.

Processing also affects the quality of the protein. Heat and moisture
involved in processing result in denaturation of the protein and may also
cause destruction of some of the more labile amino acids. Also of importance
in the case of rapeseed meal is the effect of processing on the thioglucosides
which are present in the seed.

Effect of Processing on Protein Quality

There is extensive denaturation of protein in cooking the crushed seed
prior to oil removal. For feeding purposes this is generally considered
desirable and appears to render the protein more readily assimilable by
the animal. However, the damaging effect of heat on amino acids during
processing has been noted in the processing of several oil seeds including
soybeans (10), sunflowers (16), cottonseed (7), peanuts (3), mustard seed
(14) and rapeseed (6). The basic amino acids, lysine, arginine and histidine,
as well as cystine and tryptophan have been reported to be affected. Of
these lysine appears to be the most heat sensitive. Conkerton et al. (7)
studying cottonseed meal found that autoclaving meal for 2 hours reduced
the lysine content by 37%, arginine by 15% and histidine by 13 percent.
Cystine was also reduced by 19 percent. The amino acids were deter-
mined by acid hydrolysis and ion exchange analysis. Renner et al. (16) re-
ported that autoclaving a commercial sample of sunflower seed meal for 4
hours at 15 lb (6.8 kg) steam pressure resulted in a decrease of 40% in lysine,
27% in arginine and 21% in tryptophan as determined after acid hydrolysis.
They also reported that an increase from 93 to 116 C (200 to 240 F) in the
cooker temperature and from 104 to 127 C (220 to 260 F) in the conditioner
during commercial processing of sunflower seed resulted in a decrease of
15% in the lysine content of the meal. Similarly McGhee et al. (14) on
prolonged heating of mustard seed meal found lysine was reduced by 64%,
arginine by 30% and histidine by 15 percent. Reduction in lysine content has
therefore been used as a measure of heat damage in the following discussion.

Two types of heat damage appear to take place. In one the amino
acids are bound in such a form that they are not liberated by digestion in
vivo or by enzyme hydrolysis in vitro, but are liberated by acid hydrolysis.
In the second case the amino acids appeared to be irreversibly lost and are
not recovered on acid hydrolysis. This was illustrated by Evans and Butts
(10 1 for soybean meal. A commercial solvent-extracted meal was autoclaved
for 4 hours and the lysine content determined before and after autoclaving
using both acid and enzymatic hydrolysis. Acid hydrolysis showed a loss
of 43% of the lysine and enzyme hydrolysis a loss of 61 percent. The effect of
moisture during heating was also illustrated by the above authors. Dry

heat in an oven at the same temperature, 121 C (250 F), and for the same
time as autoclaving resulted in no loss in lysine content either on enzyme
or on acid hydrolysis.

The role of sugars in the irreversible loss of lysine was also pointed
out by Evans and Butts (10). On autoclaving "alpha" protein from soybean
meal there was virtually no loss of lysine, as determined after acid hydroly-
sis, whereas autoclaving the protein plus sucrose resulted in a 47% loss of
lysine. This finding was substantiated by McGhee et al. (14) who found
a direct correlation between the reducing sugar content and lysine content
in mustard seed meal heated under varying conditions. Rapeseed, like
mustard seed, contains thioglucosides which on enzymatic hydrolysis re-
lease glucose. It may be that in oil seeds of this type the "browning reac-
tion" between sugars and amino acids presents a greater problem than in
the processing of thioglucoside-free seeds.

The various processing steps in which protein damage can occur are
in the cooker and the expeller in expeller processing; in the cooker, ex-
peller and desolventizer in prepress plus solvent extraction; and in the
cooker and desolventizer in straight solvent extraction. As can be seen
from the foregoing discussion the extent of damage in these operations
will depend on time, temperature, moisture content, reducing sugar content
and possibly on the content of other constituents in the seed. Very little
information is available on the extent of damage during these various
operations in actual commercial operation. Bensabot and Frampton (3), in
studying expeller processing of peanuts, found the lysine content was
reduced 6% on cooking for 1 hour at 112 C (234 F) and dropped another
9% in the expeller which was operated at 149 C (300 F). On cooking for
2 hours at 120 C (248 F) the lysine content dropped 17% and was reduced
by a further 17% in the expeller which was again at 149 C (300 F).
Clandinin and Tajcnar (6) determined the lysine content on rapeseed meals
from a commercial expeller plant in which the cooking temperatures had
been recorded. The crushed seed was cooked for 30 min at temperatures
ranging from 98 to 117 C (208 to 243 F) and conditioned for an additional
5 min at temperatures from 121 to 140 C (250 to 284 F) . The lysine content
of the meals varied from 3.69 to 5.37% of the protein, and was found to
correlate with the fat content of the final meal which varied from 5.2% to
9.7 percent. Expeller pressing of rapeseed to obtain a meal with less than 6%
residual fat resulted in a marked reduction in the lysine content of the
meal. The average lysine content of the meals containing over 6% residual
fat was 4.8% of the protein. Clandinin and Bayly (5) determined the
essential amino acids in a number of varieties of rapeseed using the same
method of analysis as was used for the above meals. In this case the oil
had been extracted with a petroleum solvent and the resulting meal had
not been heated. The average lysine content found for the six varieties
tested was 5.3 percent. It therefore appears that in expeller processing some
protein damage occurs even when 6% or more oil is left in the meal.

Clandinin (4) has also determined the amino acid composition of 15
samples of rapeseed meal from prepress plus solvent plants. The average
lysine content of these meals was 5.5%, indicating little loss of lysine in this
process. The crushed seed is cooked in this process and also is further
heated in the desolventizer. The damage to protein in the straight expeller
process, therefore, appears to take place in the expeller press itself but
does not occur in the very mild pressing conditions used in the prepress
plus solvent process.

Finlayson (11) found the lysine content of rapeseed meal from a
straight solvent extraction plant to be 6.6% of the protein. This high
value probably does not reflect a difference between this meal and prepress
plus solvent meal but rather a difference in the method of hydrolysis and
analysis of the amino acids. It should also be noted that all the values
reported for rapeseed meal have been obtained after acid hydrolysis of
the meal.

Effect of Processing on Thioglueosides

The thioglueosides in rapeseed, though only present in small amounts,
are important because of their possible link with various deleterious effects
observed when the meal is fed to animals. The amounts of these materials
in the various varieties, their structures and their physiological effects will be
dealt with in the following chapters. The discussion here will be limited to
alterations in the thioglueosides which may take place during processing.

In general the thioglucoside content may be altered in two ways;
first, by action of enzymes present in the seed and secondly, by chemical
modification on heating in the presence of moisture and the other con-
stituents of the seed. The effect of enzyme action in the case of oriental
mustard seed (Brassica juncea) is well illustrated by the work of Goering
(12, 13) and Mustakas (15). Mustakas investigated the effect of moisture,
temperature and time on the enzymatic hydrolysis of the thioglucoside in
the crushed mustard seed. Hydrolysis proceeded rapidly above moisture
contents of 13% and at temperatures of 40 to 70 C (104 to 158 F). At a
moisture level of 15.5% and temperature of 55 C (131 F) hydrolysis was
99% complete in 15 min and was over 90% complete in 1 minute. The
hydrolysis products of the thioglucoside in oriental mustard are glucose,
potassium bisulfate and allyl isothiocyanate (9) . The latter compound is
steam volatile so that the thioglucoside from mustard seed may be effec-
tively removed by allowing enzymatic hydrolysis to proceed and then
stripping out the isothiocyanate by steaming. In the process proposed by
Mustakas (15) this is done prior to the oil extraction and that proposed
by Goering (12) after oil extraction.

On enzymatic hydrolysis, the thioglueosides in rapeseed give rise to a
cyclic, non-steam volatile oxazolidinethione as well as to volatile isothio-
cyanates. If enzyme hydrolysis were allowed to proceed in this case only

a portion of the organic sulfur containing products could be removed by-
steaming. If hydrolysis proceeds before oil extraction, a portion of the
organic sulfur compounds enters the oil and subsequently poisons the nickel
catalyst used in hardening the oil for use in margarines and shortenings.
Reynolds and Youngs (17) have demonstrated the effect of cooking condi-
tions on the ease with which rapeseed oil may be hydrogenated or hardened.
Addition of water during cooking reduced the ease of hydrogenation of
the resulting oil. That this was linked with the thioglucosides in the seed
was substantiated by determination of these components in the resulting
meals. If no water was added during cooking, virtually all of the iso-
thiocyanates and oxazolidinethione in the seed could be accounted for in
the meal, whereas cooking with the addition of moisture resulted in a sub-
stantial drop in the amount of these compounds in the meal. Since in
Canada a large portion of the rapeseed oil produced is used in margarines
and shortenings the present method of processing involves cooking the
crushed seed without the addition of water and heating the seed to 80 or
90 C (176 to 194 F) as rapidly as possible to inactivate the enzyme
before appreciable hydrolysis can occur. Under these conditions the thio-
glucosides are left in the meal.

Reynolds and Youngs (17) also found that at cooking temperatures
above 110 C (230 F) the extracted oil did not hydrogenate satisfactorily
regardless of whether or not water was added. This cannot be attributed to
enzyme hydrolysis but may be a result of chemical breakdown of the
thioglucosides to give oil soluble sulfur-containing compounds.

In the earlier expeller meals where water was added during cooking
and relatively high temperatures were reached in the expeller some
hydrolysis and possibly chemical degradation of the thioglucosides would
be expected. This is indicated by the results of Clandinin (4) who found
the average content of isothiocyanates and oxazolidinethione for five
samples of expeller rapeseed meal to be 2.44 and 2.40 g/kg respectively.
For 15 samples of prepress plus solvent meals these values were 4.18 and
3.58 g/kg. It must be stressed that these results can only be considered
as an indication of the effect of processing because of the variation in
thioglucoside content of rapeseed with variety and with growing conditions.

Belzile et al. (1, 2) have conducted a number of laboratory studies
on various treatments of rapeseed meal following oil extraction in attempts
to modify the thioglucoside content. These treatments included hot water
extraction, dry heat, autoclaving, steam stripping and extraction with buf-
fer solutions at various pH values. The conditions used in these treatments
and the results obtained are given in Chapter 4. Although a number of
these procedures gave a substantial reduction in the thioglucoside content
or in the effect of these thioglucosides when fed to animals, none of the
procedures are readily adaptable to commercial processing.

Summary

Although information on the effect of commercial processing on the
quality of rapeseed meal is very meager some conclusions may be drawn.
Expel ler pressing results in protein damage as measured by the decrease
in lysine content of the meal. The extent of damage, which appears to
take place predominately in the cxpeller rather than in the cooking
operation, increases as the residual oil in the meal is decreased by more
rigorous processing conditions. Prepress plus solvent or straight solvent
extraction has very little effect on the lysine content of the meal as de-
termined after acid hydrolysis. No information has been obtained, how-
ever, on the content of available lysine before and after processing.

With respect to the thioglucoside content, the main alteration during
processing is through enzymatic hydrolysis. This hydrolysis can proceed
rapidly under suitable conditions of moisture and temperature. In current
processing of rapeseed no water is added during cooking and the tempera-
ture of the crushed seed is raised as rapidly as possible to inactivate the
enzyme and keep hydrolysis to a minimum. Under these conditions the
bulk of the thioglucosides are left in the meal.

References

1. Belzile, R. J., J. M. Bell and L. R. Wetter. 1963. Can. J. Animal Sci. 43:169.

2. Belzile, R. J., and J. M. Bell. 1963. Unpublished data.

3. Bensabot, L., and V. L. Frampton. 1958. J. Agr. Food Chem. 6:778.

4. Clandinin, D. R. 1964. Unpublished data.

5. Clandinin, D. R., and Louise Bayly. 1963. Can. J. Animal Sci. 43:65.

6. Clandinin, D. R., and E. W. Tajcnar. 1961. Poultry Sci. 40:291.

7. Conkerton, E. J., W. H. Martinez, G. E. Mann and V. L. Frampton. 1957. J. Agr.

Food Chem. 5:460.

8. D'Aquin, E. L., H. L. E. Vix, J. J. Spadaro, A. V. Graci, P. H. Eaves, C. G.

Reuther, K. J. Molaison, C. J. McCourtney, A. J. Crovetto and E. A.
Gastrock. 1953. Ind. Eng. Chem. 45:247.

9. Ettlinger, M. G., and A. J. Lundeen. 1956. J. Amer. Chem. Soc. 78:4172.

10. Evans, R. J, and H. A. Butts. 1948. J. Biol. Chem. 175:15.

11. Finlayson, A. J. 1964. Unpublished data.

12. Goering, K. J. 1959. Belgian Patent. 578,452.

13. Goering, K. J., 0. 0. Thomas, D. R. Beardsley and W. A. Curran. 1960. J.

Nutrition 72:210.

14. McGhee, J. E., L. D. Kirk and G. C. Mustakas. 1964. J. Amer. Oil Chem. Soc.

41:359.

15. Mustakas, G. C, L. D. Kirk and E. L. Griffin, Jr., 1962. J. Amer. Oil Chem. Soc.

39:372.

16. Renner, Ruth. D. R. Clandinin, A. B. Morrison and A. R. Robblee. 1953. J.

Nutrition 50:487.

17. Reynolds, J. R, and C. G. Youngs. 1964. J. Amer. Oil Chem. Soc. 41-63.

CHAPTER 3. THE CHEMICAL COMPOSITION OF RAPESEED MEAL

L. R. Wetter, Head, Plant Biochemistry Section
Prairie Regional Laboratory, National Research Council, Saskatoon

Introduction

Rapeseed is a member of the Cruciferae family which includes a
number of other economically important plants, e.g., cabbage, cauliflower,
turnip, mustard. There are several different types of rapeseed as discussed
in Chapter 1. Two species are grown in western Canada: summer rape,
Brassica napus var. oleifera f. annua, and summer turnip rape, Brassica
campestris var. oleifera f. annua; these are frequently referred to as
Argentine and Polish types respectively in Canadian literature. All refer-
ences to rapeseed meals in this discussion will refer to the summer type
unless otherwise designated. This chapter will deal only with those chemical
components of the seed that are important in animal nutrition.

The two economically important products of rapeseed are the oil
and the meal. The oil which is the primary product (38 to 44% of the
seed) is used in the edible oil trade. Detailed fatty acid analyses of
the oil have been made and these indicate that a high erucic acid content
is typical of rapeseed oil (16, 17 and Chapter 1). The meal, which is the
residue remaining after the oil has been removed, consists primarily of pro-
tein and carbohydrate. A little less than half of the rapeseed meal is com-
posed of protein (NX6.25). Matet, Montagne and Buchy (34) reported that
the carbohydrate content of European rapeseed cake varies from 20 to 25%
while the cellulose content is 8 percent. These values are similar to those re-
ported for linseed cake while the carbohydrate value in rapeseed
is slightly higher than for sunflower cake. In another more detailed in-
vestigation Mizuno (36) reported that de-fatted Brassica napus contained
the following simple carbohydrates: fructose (0.51%), glucose (0.21%),
sucrose (1.11%), raffinose (0.15%) and stachyose (0.19%). The same
investigator also reported the presence of a number of polysaccharides,
which contained arabinose, galactose, ribose, galacturonic acid, glucose,
xylose and rhamnose.

The proximate analyses of several rapeseed meals along with some
other oil seed meals and feeds are tabulated in Table 3.1. The protein
content of rapeseed meal is comparable with other plant meals, although
lower than those from animal sources. The crude fiber content is higher
than for other meals. The ash and nitrogen-free extract are similar for
all the oil seed meals. A recent report by Moldenhawer (37) gives the

Table 3.1. Proximate composition (%) of rapeseed meal and other feedstuff s

Feedstuff

Dry

matter

Protein

Fat

Crude
fiber

N-free
extract

Ash

Refer-
ence

Rapeseed meal

K\peller

B. campestris

94.0

35.2

7.0

15.5

20.5

6.8

0.71*

1.00*

4, 32

B. napus

93.2

43.9

6.4

13.7

23.3

5.9

0.57*

1.07*

4, 32

Solvent

B. campestris

92.0

40.5

1.1

9.3

33.9

7.2

0.66*

0.93*

Soybean meal

Solvent

89.3

45.8

0.9

5.8

31.0

5.8

0.32

0.67

Linseed meal

Solvent

90.9

35.1

1.9

8.9

39.4

5.8

0.40

0.83

Sun (lower meal

Solvent

93.0

46.8

2.9

10.8

24.8

7.7

0.43

1.04

Fishmeal, herring

92.3

70.6

7.5

0.4

3.0

10.8

2.94

2.20

Meat meal

93.5

53.4

9.9

2.4

2.6

25.2

7.94

4.03

Oats

89.1

13.3

5.1

12.0

65.5

4.1

0.11

0.39

Barley

90.3

12.6

3.0

8.2

62.9

3.6

0.09

0.47

Wheat

89.1

14.3

1.9

2.9

78.9

2.0

0.06

0.41

'Values from Clandinin (10).

proximate chemical analyses for a number of rapeseed meals from three
sources and found them to be similar to those reported in Table 3.1.
This worker reported the protein, fat, fiber and ash of Polish, Swedish
and French meals to be 33.9, 31.2, 36.5; 10.4, 8.5, 4.7; 13.8, 12.2, 12.5; and
8.3, 7.1, 5.5% respectively.

Protein and Amino Acid Content of Rapeseed Meal

The protein content has been determined on a large number of rape-
seed samples and some variations have been observed depending on the
species and the environmental conditions under which it was grown. Fre-
quently it is difficult to compare samples because it is not known whether
the meals are laboratory preparations or commercial preparations. One
source of material in western Canada is the Co-operative Test which
gives one an opportunity to compare various species of rapeseed grown
in different areas. Downey (20) has assayed a large number of these
for both nitrogen and oil content. For the years 1962 and 1963 respec-
tively, de-fatted ground seeds of Brassica napus gave mean values of 47.1
and 48.0% protein (N X 6.25) while the mean values for Brassica campestris
vvere 43.3 and 45.8% protein. The protein content of meals are generally
higher in the brown soil zones of western Canada than in the black soil
zones. This difference may be related to the fact that in general black
soil zones receive a higher rainfall than the brown. Clandinin and Bayly
(11) conducted a similar study on material grown in 1955 and found that
there were significant differences in varieties, B. napus being higher
in protein content than B. campestris; however, they found no significant
difference between stations.

97386—3

One might expect considerable change in the biological or nutritional
value of rapeseed protein following processing which would not necessarily
be reflected in a chemical analysis. Clandinin, Renner and Robblee (12)
reported that the protein analyses of two expeller-processed commercial
meals were 43.3% for B. napas and 33.9% for B. campestris. In the same
paper (see Table 3.5 (12)) values are given for seed processed at dif-
ferent temperatures and it would appear that the temperatures employed
in this process had no profound effect on the protein content. Several
Swedish workers have reported crude protein values for a number (species
unknown) of processed rapeseed meals and these values generally agree
with other reports. Biinger et al. (7) report a crude protein value for
rapeseed meal which varies from 32.8 to 40.9 percent. In another investi-
gation Jarl (28) reported that rapeseed cakes had a crude protein content
varying from 38.0 to 39.6 percent. These same workers (7, 28) indicated that
the true protein value is about 10% lower than the crude protein value.
Slightly lower values of 30 to 35% were reported by Matet et al. (34) for
commercial rapeseed cake.

In recent years there has been a modification in the processing of
rapeseed in western Canada which has resulted in a better quality meal.
The earlier meals were obtained exclusively from expeller-processed seed
while the present meals are obtained from processes which employ a
combination of expeller and solvent extraction or solvent extraction alone.
These various processes are discussed in Chapter 2. Manns and Bowland
(33) reported that the protein content of two solvent-processed meals of
B. campestris were 36.7 and 37.9 percent. Comparison of the two B. campes-
tris meals shown in Table 3.1 sugest that processing may have some effect on
protein content; however, this difference is undoubtedly related to the
difference in oil content of the meals; i.e., the solvent-extracted meal will
have a higher protein content (N X 6.25) than the expeller meal simply
because the former has less oil in it.

Advances in amino acid methodology in recent years have resulted in
complete analyses of many feedstuffs. One of the first amino acid assays
of rapeseed was published in 1946 by Roche and Michel (40) . Their values,
although limited, in general agree fairly well with present-day values.
Table 3.2 summarizes the amino acid analyses for some selected rapeseed
meals and compares them with other feedstuffs. The first three columns
compare values for rapeseed meals collected from Canada (10), Belgium
(19) and Sweden (1). The Canadian values are averages of a number of
different commercial meals from prepress solvent or solvent extraction
processes. The Swedish meal was obtained from Brassica napas (probably
a winter type) while the Canadian meals were mixtures of B. napus and
B. campestris (summer types) . The origin of the Belgian meal is not known.
There are some differences in the amino acid composition of these rapeseed
meals with the greatest variation appearing in lysine, histidine, tryptophan
and serine content. Rapeseed meal compares quite favourably with other

vegetable protein concentrates. One should point out that variations in
amino acid composition may not reflect differences in the original materia]
but rather differences in the processing methods employed.

Several workers have indicated that rapeseed is an inferior meal
because of its low lysine content {see Table 3.2). Clandinin et al. (12)
noticed that meals processed at high temperatures were nutritionally in-
ferior and low in lysine. Clandinin and Tajcnar (13) reported that there
was a correlation between lysine in the meal and the temperature at which
it was processed. They determined the lysine content of a number of
rxpeller-processed rapeseed meals for which the processing temperatures
were recorded. They observed that a decrease in the temperature of the
cooker and conditioner resulted in an increase in lysine content in the
meal. They also found that there was a direct relationship between the
oil content of the meal and the lysine content. This was believed to be
directly associated with the fact that lower oil content in the meal in-
dicated higher temperatures in the expellers. From their data they (13)
recommended that the oil content of expeller-processed rapeseed meal
should not be below 6% in order to avoid damage to the lysine present in
the meal.

Table 3.2. The amino acid content of various rapeseed meals and other protein
supplements (g of amino acid per 16.0 g of nitrogen)

Protein supplement

Rapeseed

Soybean

Sunflower

Fish meal

Tankage

Canadian

Belgium

Swedish

Reference

(10)

(19)

(1)

(19)

(46)

(6)

Number of samples

15*

Unknown

Amino acids

Arginine

5.5

7.7

5.6

8.3

9.1

5.9

5.8

Histidine

2.7

4.1

2.6

3.3

2.8

2.4

2.7

Lysine

5.3

6.8

3.5

6.5

3.5

5.7

6.0

Tyrosine

2.1

3.5

2.3

3.8

2.9

2.8

2.7

Tryptophan

1.2

2.3

2.0

1.5

1.4

1.2

0.7

Phenylalanine

3.8

4.9

4.0

4.8

5.1

4.8

5.0

Cystine

—

2.6

1.7

1.8

1.0

0.9

Methionine

1.9

2.3

1.1

1.8

2.2

3.0

2.0

Threonine

4.2

4.5

3.8

3.7

3.4

5.0

3.5

Leucine

6.7

7.6

5.7

8.1

6.9

10.0

8.6

Isoleucine

3.6

4.2

3.7

5.0

4.2

4.0

3.4

Valine

4.8

5.9

5.7

5.1

5.8

4.0

5.5

Glycine

4.8

5.2

6.3

4.4

5.6

—

Alanine

4.3

4.9

1.9

4.5

5.1

—

Serine

4.2

5.3

8.6

5.8

4.6

—

3.3

Aspartic acid

6.7

8.1

9.7

10.8

9.1

—

Glutamic acid

16.8

17.4

17.1

18.0

18.8

—

9.4

Proline

6.1

7.5

8.0

5.0

4.5

—

("rude protein (%)

37.4

36.2

57. Of

47.3

40.3

—

"Prepress-solvent and solvent-processed meals collected during 1958-61 and analyzed for amino acid content
using a Beckman/Spinco Amino Acid Analyzer.

r Percentage based on an ash and moisture-free meal.

97386— 3£

Modern methods of processing rapeseed have resulted in meals that
have a higher lysine content than meals processed a number of years ago.
The use of solvents to extract the oil from the seed or a combination of
expeller and solvent extraction allows the meals to be processed at much
lower temperatures. Investigations on the amino acid content of these
solvent-processed meals indicated that the lysine content is higher than
that of former meals. Table 3.3 summarizes the data collected by Clandinin
(10). The origin of the seed utilized for the preparation of the three meals
is unknown. It is interesting to note that the amino acid composition is
similar for most of the acids suggesting that the method of processing does
not effect them. However, this is not the case for the basic amino acids
and particularly for lysine, the content of which is from 20 to 30% higher
for solvent-processed meals than for expeller-processed. meals. It should
be pointed out that about the same increase is observed for tryptophan.
Also there seems to be some increase in the histidine and arginine content.
Gray, Hill and Branion (25) showed the same general trend when they
compared the amino acid composition of a commercial rapeseed meal with
one that was prepared in the laboratory. The laboratory meal was prepared
by extracting the seed with diethyl ether and the lysine content was much
higher in it than in the commercial meal. These workers also found that

Table 3.3. The amino acid composition of expeller

and solvent-processed meals

(g of amino acid per 16.0 g of nitrogen)

Amino acid

Expeller*

Solventf

Solvent J

Arginine

5.09

5.47

5.52

Histidine

2.40

2.61

2.76

Lysine

4.39

5.17

5.60

Tyrosine

2.16

2.06

2.18

Tryptophan

0.94

1.17

1.28

Phenylalanine

3.74

3.70

3.94

Methionine

1.88

1.90

1.95

Threonine

4.08

4.11

4.36

Leucine

6.45

6.58

6.87

Isoleucine

3.71

3.59

3.70

Valine

4.76

4.79

4.89

Glycine

4.68

4.97

Alanine

4.21

4.22

4.43

Serine

4.03

4.11

4.35

Aspartic acid

6.58

6.61

6.94

Glutamic acid

16.16

16.51

17.50

Proline

5.71

5.94

6.50

Source of material
*Saskatoon, Saskatchewan (5 different meals).
fAltona, Manitoba (10 different meals).
JLethbridge, Alberta (5 different meals).

the tryptophan and tyrosine content was lower in the commercial meal. It
was again suggested that one of the factors affecting the amino acid com-
position of the meal was the processing temperature.

Some work has been done on the amino acid content of different
varieties of rapeseed. One of the more comprehensive studies has been
made by Clandinin and Bayly (11), in which they determined and com-
pared nine amino acids in both B. napus and B. campestris. Only lysine
and histidine showed any significant differences, lysine being significantly
higher in B. campestris while histidine was higher in one variety of B. napus.
The same workers also investigated the effect of environmental conditions
on the amino acid composition of rapeseed meal and again found that the
greatest effect was exerted on the lysine content. Recently, Miller et al.
(35) in a detailed study of the amino acid composition of the seed meals
of 41 Cruciferae species compared B. napus and B. campestris and found
very little difference in the amino acid content. They also found no dif-
ference between seeds of the same variety grown in Sweden and in Canada.

Amino acid analyses performed on commercial meals derived from
different varieties indicate that there are a few differences. As indicated
above there are very few differences between expeller and solvent-processed
meals except in the lysine content (10, 32). However, a recent report by
Finlayson (23) would indicate that perhaps the amino acid composition of
rapeseed meal should be reinvestigated. Table 3.4 shows that the amino
acid content of a solvent-processed B. campestris (Arlo variety) is
markedly different than that reported by Clandinin (10) also for a B.
campestris (variety unknown). The following amino acids are considerably
higher in the report by Finlayson: lysine, tyrosine, phenylalanine, threonine,
leucine, valine, glycine, aspartic acid and glutamic acid. One is not able
to determine whether this is a varietal difference c?r whether it is a difference
in the assay technique. Recently an interesting paper by Tristram and
Smith (45) points out that great care must be taken in the determination of
amino acids, particularly when one is preparing the hydrolyzate. An illus-
tration of this point relates to the liberation and loss of certain amino acids,
e.g., considerable quantities of serine and threonine are lost after 20 hours of
hydrolysis while valine and isoleucine are completely released after 60
hours' hydrolysis. It would appear that it is extremely important to be
aware of these difficulties when one compares various amino acid assays on
feed stuffs.

Fat Content of Rapeseed Meal

In this chapter fats are considered to be the same as ether extract
values found in various tables of feed analyses, although it is recognized
that ether extracts contain materials other than fats. The fat content of
the meal will depend on the processing method employed. The earlier meals
which were mainly processed by employing Anderson expellers had fat
contents which varied from 6 to 7 percent (10, 32, 44). Meals obtained from

Table 3.4. The amino acid composition of

commercial solvent-processed

It. campestris

(g amino acid per 16.0 g of nitrogen)

Amino acid

Meal 1 (10)

Meal 2 (23)

Arginine

4.9

4.0

Histidine

2.4

2.5

Lysine

5.0

6.6

Tyrosine

1.9

3.2

Tryptophan

1.2

—

Phenylalanine

3.5

4.7

Cystine

—

1.3

Methionine

2.0

1.4

Threonine

4.2

5.3

Leucine

6.4

8.7

Isoleucine

3.5

4.4

Valine

4.7

5.7

Glycine

4.7

5.6

Alanine

4.1

5.1

Serine

4.1

5.3

Aspartic acid

6.6

8.1

Glutamic acid

16.2

24.6

Proline

6.2

8.0

solvent-processed seeds have a much lower fat content, varying from below
1 to 2 percent. There are no reports on the composition of the fat but un-
doubtedly it consists primarily of the oil found in the original seed and
therefore the fatty acid composition of it would be similar to the oil. It
is known that environmental conditions such as rainfall, soil type and
fertilizer practices have an effect on the oil content and fatty acid com-
position of oil seeds (41).

Crude Fiber Content of Rapeseed Meal

Crude fiber in animal feeds refers to lignin and insoluble carbohydrate
material, e.g., cellulose. Reference to Table 3.1 on proximate composition
of feedstuffs shows that rapeseed meal has a higher fiber content than other
oil meals. The value ranges from 9 to 16% and the fiber content does not
differ when solvent and expeller-processed meals are compared (10, 28, 32,
44). Rapeseed meal has a higher fiber content than soybean meal but it
is only slightly higher than sunflower or linseed meal.

Mineral Content of Rapeseed Meal

The ash content, which indirectly is a measure of the mineral content,
of rapeseed meal varies depending on the source of the seed. The ash for
meals obtained in western Canada vary from 6 to 7 percent (10, 32). Those
grown in Sweden are higher (44) ; a value of approximately 8% is in-
dicated. The calcium and phosphorus content of Canadian meal is 0.60
and 1.10% respectively as reported by Clandinin (10) ; slightly higher
values are reported for Swedish meals (44). In general the calcium and
phosphorus content of rapeseed meal is similar to that of other oil seed
meals (see Table 3.1). Sawhney and Kehar (42) reporting on the manganese
content in animal feeds obtained a value of 153.5 ppm for rapeseed cake.
The range for nine other vegetable seed meals was 39.5 to 80.0 ppm, thus
indicating that rapeseed is a rich source of this mineral.

Vitamin Content of Rapeseed Meal

Very little information of the vitamin content of rapeseed meal is
available. One of the more detailed investigations of the vitamin content
has been reported by Klain et al. (32) and their results are presented in
Table 3.5 along with three other meals (15). Their (32) results suggest
that there is no significant difference in the vitamin content of two
varieties of rapeseed analyzed. When compared with other vegetable seed
meals it is seen that the choline content of rapeseed meal is higher. The
niacin content of rapeseed is higher than for soybean or linseed but lower
than for sunflower meal. The thiamine and pantothenic acid content of
rapeseed meal is much lower than for the other three meals. An Indian report
(24) on B. campestris indicates a much lower value for free niacin, 42
mg per kg, than that reported in Table 3.5. However, it is impossible to
compare these values as they were carried out on samples collected in
widely separated areas.

Table 3.5. The vitamin contents (mg per kg) of expeller-processed rapeseed

meal and other oil seed meals

Viii

imin

Rapeseed (32)

Soybean
(15)

Linseed
(15)

Sunflower
(15)

Brassica
napus

Brassica
campestris

Thiamine

1.9

1.7

6.6

9.5

34.5

Riboflavin

4.2

'A. 'A

3.3

2.9

3.3

Pantotheni<

acid

9.9

8.6

14.5

17.8

41.0

Niacin

167.0

152.0

26.8

30.1

291.0

Choline

7,000

6,450

2,740

1,230

4,300

Isothiocyanate and Oxazolidinehione Content
of Rapeseed Meal

These compounds are present in rapeseed meal in only small amounts
but they may exert a considerable effect on the nutritional value of the
meal. Early reports (5, 8, 27) demonstrated that rapeseed meals caused a
depression in growth and in many cases an enlargement of the thyroid
when fed to animals or fowl. (-)-5-Vinyl-2-oxazolidinethione (also referred
to as (l)-5-vinyl-2-thioxazolidone, however this is no longer the accepted
name) which exists in rapeseed was shown to be closely associated with the
enlargement of the thyroid (3). The thioglucosides from which these sulfur-
containing compounds are derived, their enzymatic breakdown, and their
characterization in rapeseed are discussed in Chapter 4. The present chapter
will be concerned only with the quantitative assay of these" compounds and
the basis for these determinations.

The quantitative assays as described by Wetter (47, 48) are based on
the following properties: the major isothiocyanates in rapeseed meal are
volatile and therefore are removed from the reaction mixture by steam
distillation (47), the oxazolidinethione is not volatile and therefore stays
behind in the reaction mixture (48) . The volatile isothiocyanates in rape-
seed consist of two major ones, 3-butenyl isothiocyanate (CH2=CHCH2-
CH2NCS) and 4-pentenyl isothiocyanate (CH2==CHCH2CH2CH2NCS) ,
and one minor one, 2-phenylethyl isothiocyanate (30) . There are some
differences in the proportions of the two major isothiocyanates; in B. napus
the predominant one is 3-butenyl isothiocyanate (22, 31) while in B.
campestris the two major isothiocyanates are present in approximately
equal proportions (50). (-)-5-Vinyl-2-oxazolidinethione(CH2=CHCHCH2NHCS)

1 — o 1

is the primary non-volatile component and therefore remains in the reaction
mixture from which it can be extracted and assayed as described by
Wetter (48). This sulfur compound exerts a strong anti-thyroid effect and
it was isolated and identified by Astwood et al. (3). The presence of
oxazolidinethione in rapeseed meal was definitely established by Raciszew-
ski et al. (39) . The cyclic compound does not exist as such in the natural
state but rather as the thioglucoside which on enzymatic hvdrolysis yields
2-hydroxy-3-butenyl isothiocyanate (CH2=CH— CHOHCH2NCS) ' (26,
43). The latter compound is not stable and cyclizes to the (-)-(5-vinyl-2-
oxazolidinethione (29). Therefore discussion of mustard oils in this section
refers to the isothiocyanates which are the volatile sulfur compounds and
the non-volatile portion which is primarily made up of the oxazolidinethione.

There is considerable information available on the mustard oil con-
tent of rapeseed, but most of it cannot be compared because of the varia-
bility of material from different sources. First, the mustard oil content
of de-fatted seeds will be dealt with and later the effect of processing will
be discussed. Wetter and Craig (49) in a study of seven different varieties
found that the isothiocyanate content varied from 4.33 to 5.36 mg per g

of oil-free meal, while the oxazolidinethione varied from 1.33 to 5.60
mg per g of meal. Unpublished values obtained by Clandinin (10) showed
a range of 2.10 to 3.08 and 1.04 to 3.35 mg per g for isothiocyanate and
oxazolidinethione respectively in expeller meals and a range of 2.39 to
5.55 and 1.83 to 6.39 mg per g for the above mustard oils in prepress-
solvent and solvent -processed rapeseed meals. Daxenbichler et al. (18)
report the following values for a sample of B. napus; 5.9 to 6.0 and 4.3
to 6.2 mg per g for isothiocyanate and oxazolidinethione respectively.
Appelqvist (2) reported on the isothiocyanate and oxazolidinethione con-
rent of various rapeseeds grown in Sweden and he obtained somewhat dif-
ferent values as shown in Table 3.6. In a study carried out on 124 samples
of rapeseed. Nehring and Schramm (38) obtained an average isothiocyanate
content of 2.6 mg per g of oil-free seed.

The mustard oil content for different species of rapeseed varies con-
siderably as shown in Table 3.6. The major difference exists in the oxazoli-
dinethione content; B. campestris has a significantly lower content than does

Table 3.6. Mustard oil content of different rapeseed species

(all summer types)

Oxazoli-

Species

Isothiocyanate

dinethione

Reference

mg per g

B. campestris

4.80

1.56

(49)

B. campestris*

4.35

2.15

(10)

B. campestris]

7.20

0.90

(2)

B. napus

4.59

5.44

(49)

B. napus*

3.12

5.34

(10)

B. napus]

3.00

(2)

*Sol vent-processed commercial meals.
tSummer types grown in Sweden.

B. napus. The same observation was made for winter types grown in
Sweden (2). Both Wetter (49) and Clandinin (12) found that B. campestris
had a lower oxazolidinethione content than did B. napus. There appear
to be some differences in the isothiocyanate content but it is not of the same
magnitude as was observed for oxazolidinethione. Wetter (49) reports that
there is a significant difference in some of the varieties grown in western
Canada.

Only scattered results are available on the effect of environment on
the mustard oil content of rapeseed. Studies in other areas have shown that
environmental factors have an effect on the oil content and fatty
acid composition of oil seeds (41). Clandinin et al. (12) in their study
indicate that the environmental conditions under which the seed is grown

affect the oxazolidinethione content. Wetter and Craig (49) made the
same observations in a study that included six regions in western Can-
ada. Neither study was extensive enough to assess whether the differences
were due to variations in rainfall, soil type, length of day or other causes.
There was no significant difference in the isothiocyanate content reported
by either group of workers. That environmental conditions may have
an effect on the mustard oil content of rapeseed is shown in a fertilizer
study recently undertaken by Downey and Wetter (21). These investigators
added sulfate fertilizers to plots of rapeseed grown on grey wooded
soil. It was found that the response to sulfur fertilizers was much greater
for B. napus than for B. campestris. The increase associated with fertili-
zation was about two times for the oxazolidinethione and about four
times for isothiocyanate.

The effect of processing on the mustard oil content of rapeseed meal
has not been extensively studied. Raciszewski et al. (39) reported oxa-
zolidinethione values ranging from 2.4 to 4.2 mg per g for three commercial
samples. Since these meals likely were a mixture of different species, one
would have no way of comparing them with the original seed. In a study
conducted on processed and nonprocessed meals Clandinin et al. (12) con-
clude that high temperatures during the processing step increase the oxa-
zolidinethione content of rapeseed meal, whereas in another report Clan-
dinin (9) shows that excessively high temperatures lower the oxazolidine-
thione content of the meal. Processing procedures have a marked effect
on the isothiocyanate content of rapeseed. If the seed is moist and al-
lowed to stand for a period of time and is then heated or treated with
steam the isothiocyanate content will be much lower than in the original
seed. In fact this is a method employed in processing the meal to reduce
the isothiocyanate content of meal. These aspects will not be discussed here
as they are dealt with in Chapter 2.

Summary

The chemical composition of rapeseed meal has been discussed. Much
of the information gathered pertains to two areas; the amino acid com-
position and the mustard oil content of rapeseed meal. The amino acid
composition of the meal is comparable to other vegetable protein meals.
Although there is some variation in the amino acid composition, it is not
possible at the present time to ascertain what is causing these differences.
There are definite varietal differences in the mustard oil content and com-
position of rapeseed meal. Here also there are variations that cannot be
accounted for but undoubtedly are related to such environmental factors
as rainfall, soil type and soil nutrients. The information on the vitamin
and mineral content of the meal is limited, however it indicates that they
are similar to other plant meals. It is hoped that more information re-
garding the mineral and vitamin content of rapeseed meal will be forth-
coming in the future.

References

1. Agren, G. L952. Acta Chem. Scand. 6:608.

2. Appelqvist, 1.. A. 1962. Acta Chem. Scand. 16:1284.

3. Astwood, K. B., M. A. Greer and M. G. Ettlinger. 1949. J. Biol. Chem. 181:121.

4. Bell, J. M.. R. Iv. Downey and L. R. Wetter. 1963. Can. Dep. Agr. Pub. 1183.

5. Blakely. R. M., and R. W. Anderson 1948. Sci. Agr. 28:393.

6. Block. R. J.( and Diana Boiling. 1951. The Amino> Acid Composition of Proteins

and Foods. 2nd ed. Charles Thomas, Springfield. Illinois.

7. Bunger, H.. J. Schultz, H. Augustin, J. Keseling, W. Kirsch, K. Richter, J. Herbst,

V. Stang, W. Wohlbier and W. Schramm. 1936. Landw. Versuchsstat. 124:241.

8. Carroll. K. K. 1949. Proc. Soc. Exp. Biol. Med. 71:622.

9. Clandinin, D. R. 1962. Proc. Xllth World's Poultry Congr., p. 259.

10. Clandinin, D. R. 1964. Unpublished data.

11. Clandinin, D. R., and Louise Bayly. 1963. Can. J. Animal Sci. 43:65.

12. Clandinin. D. R.. Ruth Renner and A. R. Robblee. 1959. Poultry Sci. 38:1367.

13. Clandinin, D. R., and E. W. Tajcnar. 1961. Poultry Sci. 40:291.

14. Composition of Cereal Grains and Forages. 1958. Pub. 585. Nat. Acad. Sci., Nat.

Res. Council, Washington, D.C.

15. Composition of Concentrate By-products Feeding Stuffs. 1956. Pub. 449. Nat. Acad.

Sci., Nat. Res. Council, Washington, D.C.

16. Craig, B. M. 1961. Can. J. Plant Sci. 41:204.

17. Craig, B. M., and L. R. Wetter. 1959. Can. J. Plant Sci. 39:437.

18. Daxenbichler, M. E., C. H. Van Etten, F. S. Brown and Q. Jones. 1964. Agr.

Food Chem. 12:127.

19. De Vuyst, A., W. Vervack, M. Van Belle, R. Arnould and A. Moreels. 1963.

Agricultura (Louvain) 11:385.

20. Downey, R. K. 1964. Unpublished data.

21. Downey, R. K., and L. R. Wetter. 1964. Unpublished data.

22. Ettlinger, M. G., and J. E. Hodgkins. 1955. J. Amer. Chem. Soc. 77:1831.

23. Finlayson, A. J. 1965. Can. J. Plant Sci. 45:184.

24. Ghosh, H. P., P. K. Sarkar and B. C. Guha. 1963. J. Nutrition 79:451.

25. Gray, Jean A., D. C. Hill and H. D. Branion. 1957. Poultry Sci. 36:1193.

26. Greer, M. A. 1956. J. Amer. Chem. Soc. 78:1260.

27. Hercus, C. E., and H. D. Purves. 1936. J. Hyg. (Cambridge) 36:182.

28. Jarl, F. 1946. Husdjursfors. Anst., Medd. 20:1.

29. Kjaer, A. 1960. Progress in the Chemistry of Organic Natural Products, 18:122.

Springer-Verlag, Vienna, Austria.

30. Kjaer. A., and R. Boe Jensen. 1956. Acta Chem. Scand. 10:1365.

31. Kjaer, A., J. Conti and K. A. Jensen. 1953. Acta Chem. Scand. 7:1271.

32. Klain, G. J., D. C. Hill. H. D. Branion and Jean A. Gray. 1956. Poultry Sci.

35:1315.

33. Manns, J. G., and J. P. Bowland. 1963. Can. J. Animal Sci. 43:252.

34. Matet, J., R. Montagne and A. Buchy. 1949. Oleagineux 4:145.

35. Miller, R. W., C. H. Van Etten. Clara McGrew, I. A. Wolff and Q. Jones. 1962.

J. Agr. Food Chem. 10:426.

36. Mizuno, T. 1958. Nippon Nogei Kagaku Kaishi 32:340.

37. Moldenhawer, K. 1962. Postepy Nauk Rolniczych 9:17.

38. Nehring, K., and W. Schramm. 1950. Landw. Forsch. 2:126.

39. Raciszewski, Z. M., E. Y. Spencer and L. W. Trevoy. 1955. Can. J. Technol.

33:129.

40. Roche, J., and R. Michel. 1946. Oleagineux 1:205.

41. Sallans, H. R. 1964. J. Amer. Oil Chem. Soc. 41:215.

42. Sawhney, P. C, and N. D. Kehar. 1961. Amer. Biochem. Exp. Med. 21:111.

43. Schultz, 0. E., and W. Wagner. 1956. Arch. Pharm. 289:597.

44. The National Animal Experiment Station. Ultima, Uppsala 7, Sweden. Bull. 45.

45. Tristram, G. R., and R. H. Smith. 1963. Advances in Protein Chem. 18:227.

46. Walford, L. A., and C. G. Wilber. 1955. Advances in Protein Chem. 10:289.

47. Wetter, L. R. 1955. Can. J. Biochem. Physiol. 33:980.

48. Wetter, L. R. 1957. Can. J. Biochem. Physiol. 35:293.

49. Wetter, L. R., and B. M. Craig. 1959. Can. J. Plant Sci. 39:395.

50. Youngs, C. G. 1964. Unpublished data.

CHAPTER 4. GOITROGENIC PROPERTIES

J. M. Bell, Professor of Animal Science
University of Saskatchewan, Saskatoon
and R. J. Belzile, Assistant Professor of Animal Science
Laval University, Quebec City

Introduction

The use of rapeseed meal as a protein supplement in livestock and
poultry rations has often resulted in adverse effects on growth and re-
production. There have been appreciable differences, however, according
to animal species, age and sex, as well as method of processing of rape-
seed for oil extraction and meal preparation; species or variety of rape;
year the crop was grown and other factors.

The undesirable principles in rapeseed meal are derived mainly from
the thioglucosides which yield isothiocyanates and oxazolidinethione
upon enzymatic hydrolysis. These or related compounds are characteristic
of many plants or their seeds, particularly in the Cruciferae, or mustard
family, to which the genus Brassica belongs.

The "Mustard Oils"

The existence of the so-called "mustard oils" (isothiocyanates and
oxazolidinethione) has been known for a long time. According to Chal-
lenger (19), early users of mustard probably knew that it was necessary
to grind the seeds with water to produce the characteristic odor but this
observation is historically attributed to Portas in 1608. The Dutch scien-
tist Boerhaave in 1732 appears to have been the first to prepare oil of
mustard and describe its properties. Dumas and Pelouze in 1833 undertook
elementary analysis of mustard oils and showed that these could yield
ammonia and thiourea. This work is generally regarded as the beginning
of the modern investigations relating to mustard oil and its production
from plants and seeds.

Reports published up to 1948 (66, 74) indicated that more than 30
isothiocyanates had been isolated from plant sources. However, many more
compounds of this type have been found since then, such that the num-
ber now probably exceeds forty.

AIM isothiocyanates (from sinigrin), p-hydroxybenzyl isothiocyanate
(from sinalbin), sec. -butyl isothiocyanate and beta-phenylethyl isothio-
cyanate appear to have been the only mustard oils of known structure
prior to 1952 (44) . At that time a systematic investigation of the natural
mustard oils and their thioglucosidic precursors was begun, principally by

Kjaer and his Danish colleagues. Much of this work, still in progress, has
been concerned with plants and seeds belonging to the natural order
Cruciferae but recently other orders have been studied (3, 34, 43, 45, 46,
48, 49, 65, 67).

The Thioglucosides

In 1840, Bussy (19) obtained a substance, sinigrin, by aqueous ex-
traction of pre-heated black mustard seeds (Brassica nigra L.). When this
compound was treated with "myrosin", previously isolated from the same
seeds by Boutron and Fremy (19), oil of mustard (allyl isothiocyanate)
was liberated. This clearly established the simultaneous presence of a
thioglucoside and thioglucosidase in the same seed. Sinigrin was the first
thioglucoside isolated from plant sources of the many now known. The
general formula is:

S — Glucose
/
R— C

\
N— O— SO2— O— K

Sinablin has a more complex structure. Instead of yielding KHSO4
upon hydrolysis it gives, in addition to glucose and p-hydroxybenzyl iso-
thiocyanate, the hydrogen sulfate of an ester derivative of choline and
sinapic acid, known as sinapin sulfate. Sinalbin is present in rapeseed
(47) and Clandinin (22) and Schwarze (69) ascribed to it the cause of
the bitter taste of the seed.

Myrosinase

The thioglucosidase, myrosinase, is the enzyme usually responsible for
the hydrolysis of the mustard oil thioglucosides found in many repre-
sentatives of the Cruciferae, Tropeolaceae, Capparidaceae and Rose-
daceae. Boutron and Fremy (19) are credited with the first crude enzyme
preparation in 1840 although they apparently did not realize that they
had an enzyme. They extracted black mustard seeds with cold alcohol
and obtained a solid substance subsequently named myrosin.

Myrosinase effects the cleavage of a thioglucoside to yield isothio-
cyanate, bisulfate and glucose. Two explanations have been proposed for
the enzymatic breakdown. The earlier explanation proposed by Gadamer
(29) suggested that the enzymatic decomposition involved a simple hydro-
lytic mechanism yielding only isothiocyanates; other compounds such as
nitriles arising by a purely chemical reaction possibly catalyzed by the
bisulfate ion. Such an explanation is due partly to an erroneous early
concept of the structure of thioglucosides and partly to the absence of
adequate information concerning the products of their breakdown. Gada-
mer's enzymatic mechanism is given below:

S — Glucose
/ (myrosinase)

r_N=C > R— N=C=S + Glucose + HSO4

\ H2O

O— SO2— o-

4ft

His formula for fchioglucosides as well as his reaction mechanism remained
unchallenged for 60 years. In 1956, Ettlinger and Lunden (28) proposed a
revised structure for thioglucosides and a new mechanism of reaction
(see formula on page 46). During the intervening period, various ob-
servations had emerged which suggested that not all of the decomposition
products of thioglucosides could be readily explained by Gadamer's for-
mula, especially the occasional simultaneous formation of nitriles and iso-
thiocyanates or thiocyanates and mustard oils. This new structure per-
mitted a second explanation of hydrolysis by myrosinase, more complex in
nature but also more in line with the experimental facts. According to
this view, the action of myrosinase can give rise to isothiocyanates, thio-
cyanates or nitriles but the prominent reaction involving a Lossen trans-
formation yields isothiocyanates (in some cases thiocyanates) :

r— c

S— Glucose

N— O— SO2— O-

( myrosinase)
H2O

R— C

N— O— SO2— O- J

+ Glucose

R— N=C=S
(isothiocyanate)

R— C

S— Glucose

N— O— SO2— O-

(myrosinase)
H2O

R-C

(Lossen transformation)
+ HSOl

+ Glucose

R— S— C=N

(thiocyanate)

N— O— SOs— O- J

(Lossen transformation)

+ hso7

In a reaction where nitrile formation occurs, the anion is preferentially
eliminated:

r— c

S— Glucose

N— O— SO2— O-

(myrosinase)
H2O

R— C

+ HSO4

N— OH J
H2O

R— C h Glucose

N— OH

4
R— C=N + S + H2O

The simultaneous occurrence of a nitrile and an isothiocyanate has
been observed on several occasions. Will and Korner in 1863 (19) frac-
tionated two samples of natural oil from the seeds of black mustard
(Brassica nigra L.) and found allyl cyanide as well as allyl isothiocyanate.
Schultz and Gmelin in 1954 (68) reported that when glucoiberin, a thio-
glucoside obtained from Iberis amara L. (rocket candituft), was treated
with myrosinase-free sulfur, a nitrile and relatively little isothiocyanate

were produced. In 1948, Schmid and Karrer (66) isolated sulforaphene and
the corresponding nitrile from radish seeds {Raphanus sativus L.) although
enzymatic decomposition was not employed. The isolation of a nitrile and
the corresponding isothiocyanate (4-pentenyl isothiocyanate) from rapeseed
(Brassica napus L.) has also been reported by Schmalfuss (65), in 1936,
using direct distillation procedures. Later Kjaer (48) treated crushed
rapeseed with myrosinase and isolated by chromatography 4-pentenyl
isothiocyanate as one of the products of the reaction but not the nitrile.
Other cases of this kind are reported in the literature. These results indicate
that, in certain circumstances, thioglucosidic breakdown can give rise to
nitrile formation.

Recently Gmelin et al. at Helsinki (31) have found that the so-called
garlic odors of some of the representatives of the Cruciferae family are due
to the enzymatic decomposition of the thioglucosides to yield thiocyanates.
This is true of the seeds of penny-cress {Thlaspi arvense L.) and two
species of pepper-grass (Lepidium ruder ale L. and Lepidium activum L.)
which liberate allyl thiocyanate, benzyl thiocyanate and a mixture of
benzyl thiocyanate and isothiocyanate respectively. Attempts by these
workers to separate a thiocyanate-forming enzyme from these seeds were
unsuccessful since such enzyme preparations, in in vitro experiments, have
always split glucosides to isothiocyanate in the normal way. They have
obtained evidence, however, suggesting that in some of these plants there
is a certain factor which regulates the migration of the radical to the S-atom
instead of the N-atom during the Lossen transformation and concluded
that it is possible that the quantity of this factor determines the presence
or absence of thiocyanate formation.

Since the discovery of myrosinase, controversy has existed as to
whether myrosinase is a one- or a two-enzyme system. Early workers (64,
76) believed that it consisted of two entities: a thioglucosidase capable of
splitting the glucose moiety and a sulfatase capable of removing sulfur.
Their assumption was based partly on the fact that the amount of enzyme
required to remove the optimal quantity of glucose was greater than the
amount of enzyme required to split off the optimal amount of sulfur. In
contrast, more recent work favors the theory of a one-enzyme system for
myrosinase (28, 59) . This was based on the inability by fractional precipita-
tion, electrophoresis and other methods to separate two enzymes. However,
more recently, Gaines and Goering (30) have obtained results showing con-
clusively the dual nature of myrosinase. A crude enzyme preparation from
Brassica juncea L. (Indian mustard) was fractionated with ammonium
sulfate and diethyl amino ethyl cellulose. A fraction with sulfatase and
another with thioglucosidase were obtained. They also showed that total
hydrolysis only occurred when the two components were present.

Myrosinase is probably an -SH dependent enzyme since it is in-
activated by inhibitors of that chemical group (64) ; also it is activated
in vitro by ascorbic acid (27).

Greer (35) has discussed the finding of enzymes in the gastro-
intestinal tract capable of hydrolyzing thioglucosides. Several bacterial
species were found to possess appropriate enzymes, notably E. coli and A.
aerogenes.

Chemical Nature of Thioglucosides in Rapeseed

Although the mustard oil of rapeseed had been repeatedly investigated,
no clear picture of its chemical nature existed until Kjaer's investigations
in 1952. In 1899, Jorgensen (41) attributed the toxicity of rapeseed cakes
to a C5 or Ce isothiocyanate in addition to the allyl derivative. In 1901,
Sjollema (70) reported the isolation of a mustard oil to which he ascribed
the structure: CH2=CH — (CH2)2 — NCS. Stein (71) obtained from Indian
rapeseed cakes {Brassica jancea L.) a Cs compound which he regarded as
CHs— CH=CH— CH2— NCS. In 1936, Schmalfuss (65) again reported
the isolation of CH2=CH — (CH2)2 — NCS, also its corresponding nitrile and
a higher boiling isothiocyanate of unknown structure. Andre and Delaveau
(2) found evidence in rape for the presence of three individual volatile
isothiocyanates but again no suggestion as to their chemical nature. That
three volatile mustard oils are present in rapeseed was later confirmed by
Kjaer (44, 48). He succeeded in isolating and conclusively identifying
3-butenyl and 4-pentenyl isothiocyanate. The third factor, a minor one,
is probably 2-phenylethyl isothiocyanate. Astwood et al. in 1949 (3)
isolated and characterized (-)-5-vinyl-2-oxazolidinethione from rapeseed.

Using paper chromatography, Kjaer (48) has found evidence for the
presence of six thioglucosides in Brassica napus L.: three major and three
minor ones. His results on aqueous extracts of the seeds are given in
Table 4.1.

The same pattern has been obtained repeatedly for seed samples of
different origin and is therefore regarded as characteristic of varieties of
Brassica napus L. This description accounts for the isothiocyanates in

Table 4.1. Thioglucosides and mustard oils in Brassica napus L.

Order of

Thioglucoside

Mustard oil

from origin

Nature

Magnitude

Nature

Characteristic

Probably gluco-
coiberin

Minor

3-Me sulfinyl propyl
isothiocyanate

Nonvolatile

Progoitrin

Major

Goitrin

Nonvolatile

Sinalbin

Minor

p-OH benzyl
isothiocyanate

Volatile

Gluconapin

Major

3-butenyl

isothiocyanate

Volatile

Gluco-
brassiconapin

Major

4-pentenyl

isothiocyanate

Volatile

Probably gluco-
nasturitium

Minor

2-phenyl ethyl
isothiocyanate

Volatile

97386—4

rapeseed, a subject of discussion in the literature through more than five
decades, but no mention is made by Kjaer of the presence of sinigrin in
rapeseed as reported by Matet (56).

With minor variance, Gmelin et al. at Helsinki (31) have corroborated
Kjaer's work. In some Brassica species, they have found five and in others
only two thioglucosides. Both Kjaer and Gmelin agreed that progoitrin
and gluconapin are the chief thioglucosides in rapeseed species.

Goitrin and its precursor progoitrin deserve special mention. In 1949,
Astwood and Greer (3) isolated a compound from several kinds of Brassica
seeds (including Brassica napus L.), which turned out to be (-)-5-vinyl-
oxazolidinethione. This compound absorbs strongly at 240 millimicrons.
It was found to be goitrogenic and to posses an activity equal to thio-
urical when injected into humans and 20% as active when injected into
rats. It was given the descriptive name: goitrin. These workers found
that goitrin was not formed when the enzymes were destroyed by suspend-
ing the seeds in boiling water but that subsequent treatment of the filtrate
with myrosinase liberated it. Therefore goitrin exists in the seed as a glu-
coside and the latter was given the name: progoitrin. Recently Greer
(34) isolated progoitrin and described its properties. This compound ab-
sorbs at 227 millimicrons. Other oxazolidinethiones are also known to
exist in nature: L-5:5-dimethyl-2-oxazolidinethione and L-5-methyl, 5-
ethyl-2-oxazolidinethione in the seeds of Coringia orientalis L. (hare's-
ear mustard) and L-5-phenyl-2-oxazolidinethione in Reseda lutea L.
(cut-leaved Mignonette) (19).

Evidence based on the ultraviolet shift experienced during enzymatic
hydrolysis and on the infrared spectrum of progoitrin indicates that
oxazolidinethione is not preformed in the thioglucoside molecule but arises
from cyclization following enzyme action. The reaction is probably the
following:

S— Glucose
I

CH2=CH— CH— CH2-C > CH2=CH-CH-CH^NCS + Glucose

(myrosinase)
OH N— O— SO2— O- OH + HSO*

(cyclization)

CH2 NH

I I

CH2=CH— CH C=S

\ /

(goitrin)

Pitt-Rivers (62) in 1950 postulated that 3-butenyl isothiocyanate may
give rise to goitrin by cyclization, perhaps via an enzyme. Clandinin (25)
has found that heat increases the goitrogenic properties of rapeseed meal
by converting isothiocyanate to (-)-5-vinyl-2-oxazolidinethione. Perhaps
the mechanism is the following:

Cm— N (enzyme ?) CH> — NH

I I > I I

CH2=CH— CH2 C=S (heat ?) CH2=CH— CH C=S

\ /
3-butenyl O

isothiocyanate goitrin

Evidence for Goitrogenic Properties

The existence of an antithyroid substance has been known for many
years but the first definite evidence of a goitrogen in food was discovered
accidentally by Chesney et al. in 1928 (20). They found that a colony
of rabbits on a maintenance diet of fresh cabbage, oats and hay developed
truly remarkable goiters, in one case the thyroid reaching 43 g as against
an average of 0.23 g for 644 normal rabbits. By the process of elimination,
they concluded that cabbage was responsible for this phenomenon (21).
Marine (54, 55), McCarrison (57, 58), Blum (16, 17) and others were
able to reproduce this phenomenon of "cabbage goiter" although some in-
vestigators were less successful (35).

Earlier, SjoIIcnia in 1901 (70) had identified crotonylisothiocyanate
as a constituent of the essential oil fraction of rapeseed. Viehover et al.
(75) in 1920 found crotonyl- and allyl-isothiocyanates present in rape and
mustard seeds respectively, and established their relative toxicities with
rabbits but did not associate the adverse effects with thyroid dysfunction.

Kennedy and Purves in 1941 (42) appear to have been the first to
report goitrogenic properties attributable to components of rapeseed.
Having found previously that drying could destroy the activity of cabbage,
it was reasoned that the goitrogens might be glucosides (38). Therefore
they turned to those seeds long known to be rich in glucosides: rape and
mustard. These seeds produced enlarged thyroids (22 to 25 mg/100 g of
body weight) when fed to rats for 30 days. The appropriate generic term
"Brassica-seed goiter" was coined to describe this effect.

Extending these investigations they found that young rats would de-
velop thyroids three- to four-fold larger than the controls even though
the iodine intake was adequate (42) . They also found that in rats the
goitrogenic effect reached a plateau after feeding rapeseed for 3 weeks but
the thyroid reaccumulated some colloid after 9 or more weeks on treatment.
However, the hypertrophy of the gland was not alleviated. Recently similar
results were obtained in rats and pigs (51, 52, 53).

It soon became apparent that all types of expeller-processed rape-
seed meal produced goitrogenic effects of various intensity in non-ruminants.
Pettit in 1944 (61) reported that 20% rapeseed meal in a chick starter
caused thyroid hytertrophy. Turner in 1946 and 1948 (72, 73) reported that
the feeding of various levels of rapeseed to chicks led to increased thyroid
sizes. Recently Clandinin (24) reported that upon feeding expeller meal
to chicks, the thyroid-to-body-weight ratio doubled when a 15% Polish
(summer turnip rape) or 5% Argentine (summer rape) level was used, the
difference between the two types of meal being due presumably to the varia-
tion in goitrogen content. Using turkey poults, Blakely and Anderson (13)
observed a five- to six- fold increase of the thyroid weight as a result of
feeding rations containing up to 20% rapeseed meal. In rats, the goitrogenic
effect was evident when 10% Argentine meal was incorporated in a ration

97386—44

(40), and Manns et al. (53) have shown that although the serum PBI
was not affected by rapeseed, the standard metabolic rate was lowered. Bell
(6) observed some thyroid enlargement due to the feeding of Argentine
meal to mice and it is known that metabolic rate is reduced upon pro-
longed feeding. The goitrogenic effect of rapeseed feeding to swine has
been repeatedly demonstrated (40, 60) and Manns et al. (53) have shown
that the PBI is reduced upon prolonged feeding.

There is no evidence indicating that rapeseed meal is goitrogenic to
ruminants. Bezeau et al. found no thyroid enlargement in ewes fed as
much as 30% rapeseed meal in their rations (12). Rapeseed meal has been
used in cattle feeds in Europe for many years with no apparent ill effects.

Although the goitrogens of cabbage appear to be counteracted by
sodium iodide either as fertilizer applied to the growing plant (18) or as a
supplement in the animal diet (55), only partial correction, if any, has
been obtained with iodide in diets containing rapeseed meal and involving
several animal species (9, 50, 63). On the other hand, more success resulted
from the use of iodinated casein or thyroxine. These substances counteracted
to varying degrees the goitrogens of rapeseed when added to rat (63),
turkey poult (14, 15) and chick (50) diets. Other species like the mouse
and the pig have not responded satisfactorily to the feeding of thyroid
hormones (7, 60).

It has been shown by Kennedy and Purves (42, 63) that hypophy-
sectomy will prevent the development of thyroid hypertrophy. The hypophy-
sectomized rats possessed glands weighing no more than 6.4 mg as com-
pared to 44 mg for the intact controls. They also demonstrated that
rats placed on the "active" diet for 2 months and then hypophysectomized
showed colloid formation and a reduction of thyroid size. Thyroxine
abolished thyroid hyperplasia induced by rapeseed feeding but iodide or
diiodotyrosine did not to any significant extent, even when fed in large
doses. These observations pointed to one conclusion: a rapeseed diet pro-
duces thyroid hypertrophy by interfering with the synthesis of thyroxine;
this in turn stimulates the anterior pituitary to produce TSH which acts
on the thyroid and causes hypertrophy and hyperplasia. With the feed-back
mechanism for thyroid control interrupted, goitrogenesis continues. The
observation by Kennedy in 1941 (42) and Manns et al. (53) in 1963 that
an involution of goitrogenesis was evident after 2 months' feeding of rats
is more difficult to explain on the basis of Kennedy's hypothesis.

A recent study of the thyroid glands of growing chickens and laying
hens fed rapeseed meal with and without iodide supplementation was made
by Clandinin (24). In growing chicks, the feeding of rapeseed was found
to increase the thyroid size by a rise in the number of follicles and epithelial
cells. When iodine was added to the rapeseed diet, the glandular enlarge-
ment was caused by increased follicular size and colloid storage. A some-
what similar histological picture held true for the laying hens. Such evidence

indicates that iodine supplementation, although mostly ineffective in
counteracting goitrogenesis, may have a marked influence on the amount
of colloid stored in the gland (25).

Mottled thymus, hypertrophied kidney and liver may follow the
ingestion of rapeseed (5, 33). Manns et al. (53) found that adrenal and
gonad weights, in rats and pigs, were unaffected by dietary rapeseed meal
and that these glands also appeared normal histologically. Haas (37)
detected a drop in the eosinophil count and a depletion in ascorbic acid
content of the adrenals of rats following ingestion of mustard oils.

Greer et al. (36) have classified antithyroid compounds into seven
categories according to their modes of action. Some obviously do not apply
to the problem of toxicity in rapeseed meal, according to information
presently available. Among those deserving comment, however, m this
discussion is thiocyanate, the compound responsible for "cabbage goiter"
and which apparently interferes with the concentration of iodine in the
thyroid gland by a process of competitive inhibition. While thiocyanates
as such do not appear to be involved in rapeseed meal toxicity these com-
pounds in foliage may be related to the ultimate goitrogenicity of the seeds
of Brassica species.

Of particular interest with regard to rapeseed is that group ol sub-
stances which exert antithyroid activity through interference with the
organic binding of iodine. The coupling of two iodinated tyrosine molecules
appears to be the most sensitive stage but iodination of tyrosine probably
is also impaired. Compounds in this group include the thionamides, aniline
derivatives and oxazolidinethione. The only isothiocyanates having sig-
nificant antithyroid activity are those capable of cyclizing to form
oxazolidinethione.

There is evidence that several of the antithyroid substances found in
Brassica seeds can inhibit metabolism in tissues in vitro and therefore
without direct involvement with thyroxine (4, 10 and others). However,
Greer et al. (36) claim that few if any of these compounds are capable of
blocking the action of thyroxine once it has left the thyroid. The authors
note possible exceptions with the comment that certain thionamides may
affect the metabolism or retard the breakdown of circulating thyroid hor-
mone. For instance, rats treated with propylthiouracil and simultaneously
with a "compensating" level of thyroxine develop goiters. This has been
explained as failure of circulating thyroxine to be converted to an "intracel-
lularly active" form, one consequence of which is increased production of
TSH by the pituitary.

Aside from goitrogenesis, growth inhibition as a consequence of thyroid
malfunction has been a frequently observed result of rapeseed toxicity.
Since the early observations of Viehover et al. (75) many investigators
have confirmed these results for young animals of numerous species (5).
The recent literature indicates that the substitution of solvent- for ex-
peller-processed meal has alleviated the problem of growth inhibition to

a marked extent. It is possible that improved temperature control in the
oil extracting plants, resulting in protein of higher biological value, is
responsible for part of the noted improvement (26). Altered activity of
the enzyme myrosinase may also be involved.

While growth retardation occurred in chicks fed levels as low as
10% of expeller meal (5), a recent report by Clandinin (23) on the feeding
value of solvent meal suggested that its growth-promoting value approaches
that of soybean meal when incorporated in chick diets at levels of 10 or
15 percent. Hussar and Bowland in 1959 (40) observed that the substitution
of soybean by rapeseed expeller meal in growing swine rations to the extent
of 10% of the total ration caused significant reductions in growth rate and
feed efficiency. However, the substitution of 15% solvent meal had no
effect on feed utilization although some growth depression was experienced
(51). Swine carcass characteristics appeared to be unaffected by rapeseed
meal feeding.

Growth inhibition has been used in mouse studies (6, 7, 8, 11) as an
index of toxicity in rapeseed meal and it has been shown that isothiocyanates
and oxazolidinethione, enzymatically liberated from their parent glucosides,
have about equal effects on growth rates. For instance, 0.1% isothiocyanate
plus oxazolidinethione in the diet resulted in extreme growth depression in
mice regardless of the ratio of these two compounds; a dietary level of
0.2% proved lethal but it was observed that males were affected somewhat
more severely than females.

Adverse effects have also been observed by the senior author when 7%
rapeseed meal (of either B. campestris L. or B. napas L. origin) was
included in rations fed to pregnant gilts. Litter size was reduced, lactation
was impaired and the gilts displayed physical weakness after farrowing.
Similar responses were observed earlier with mice when first-litter immature
females were unable to tolerate the added stress of lactation when diets
containing 30% rapeseed meal were fed. The activity of myrosinase and
the specific amounts of isothiocyanate and oxazolidinethione were not deter-
mined in these studies.

Modification of Feeding Value of Rapeseed Meal

Extraction Procedures

Improvements in the feeding value of rapeseed meal following aqueous
and alcohol extraction have been reported (1, 6, 39). Bell (6) found that
acid hydrolysis resulted in little if any improvement in toxicity. Schwarze
in 1949 (69) and Goering in 1961 (32) reported on removal of the mustard
oils from rapeseed meal by moistening the ground seeds with cold water,
adding myrosinase if necessary and finally steam stripping to remove the
volatile "oils". Oxazolidinethione, being non-volatile, remained in the meal.
Goering digested -the meal at 45-55 C with water in the ratio of six to

eight volumes of water to one volume of rapeseed meal. The risk of im-
pairing the quality of the rapeseed oil by so treating ground rapeseed has
been discussed by Clandinin (23).

Belzile and Bell (10), using both B. campestris and B. napus petroleum-
ether-extracted meals, studied the effects of hot (90 C) water extraction
on isothiocyanate and oxazolidinethione contents (77, 78) and on toxicity
as revealed by mouse bioassays. Meals thus treated were found devoid of
myrosinase and there wras no evidence of thioglucoside hydrolysis having
occurred. The extraction of the meals with hot water resulted in about
20% of the original meals going into "solution" and in some apparent
alteration of the toxic constituents. From 27 to 48% more isothiocyanate
and 8 to 11% less oxazolidinethione were recovered in the residues and
extracts than existed in the original meals. This resulted in a net increase
in apparent toxicity of about 3% for Swedish (summer, B. napus) and 34%
for Polish (summer turnip, B. campestris) meal. In subsequent bioassays
with mice fed diets containing a total of 0.1% isothiocyanate plus oxazoli-
dinethione the extracted residues of the two types of meal gave similar
responses and confirmed the chemical appraisals of potential toxicity by
effecting a 10% reduction in growth. The extracts proved less toxic than
anticipated from the chemical assays, especially in the case of B. campestris,
where isothiocyanate predominated, in contrast to B. napus where isothi-
ocyanate occurred at half the concentration found for oxazolidinethione.

Dry Heat

Solvent-extracted meals were subjected to 12 hours' oven treatment
at 135 C and tested for toxicity as indicated above (11). Such treatment
destroyed myrosinase activity but preliminary studies indicated that the
enzyme was inactivated rather slowly since some activity remained after
6 hours at 135 C. There was no significant reduction in the amounts of
isothiocyanates or oxazolidinethione following cooking but these remained in
glucoside form. When fed to mice in bioassay tests, dry-heated meals were
markedly superior to unheated meals, thus confirming the role of the
enzyme in the toxicity picture (9).

Steam Pressure

Similar meals (11) were subjected to steam autoclaving for 15 min
at 1.2 kg/cm2 (17 lb/inch2) pressure in a pre-heated autoclave following
which the meals were dried in vacuo at 50 C. Under these conditions myro-
sinase was rapidly destroyed without any apparent effect on the thiogluco-
side content of the meal. Feeding steam-treated meals to mice as 10 to 20%
of the diet allowed normal growth and feed consumption whereas untreated
meal, containing active enzyme, permitted only 10% of normal growth
rate. It has been shown that the enzyme myrosinase per se produces no
adverse effects when fed in diets free of thioglucosides (9).

In other studies these workers compared 0.6 and 1.2 kg/cm2 (9 and
17 lb/inch2) autoclaving for periods of up to 2 hours' duration. Solvent-ex-
tracted, enzyme-free commercial rapeseed meal was used. It was found that
the amount of pressure used had a marked effect on the rate of disappear-
ance of isothiocyanates and oxazolidinethione. In effect, doubling the pres-
sure doubled the disappearance rate but oxazolidinethione disappeared twice
as fast as isothiocyanate. At the higher pressure over 90% of the original
oxazolidinethione and 75% of the isothiocyanate had disappeared in 2 hours.

Bioassays were conducted on meals that had been autoclaved for
0, 16, 30, 60, 120 and 180 min at 1.2 kg/cm2. The meals were also tested
in rations containing 0.15% purified myrosinase. In the absence of added
enzyme, growth rates were near normal in all cases but when myrosinase
was reincorporated into diets containing meals that had received 15 or 30
min autoclaving to permit thioglucoside hydrolysis, gains were significantly
depressed. Meals treated for 60 min or longer produced normal gains re-
gardless of presence or absence of enzyme. It is thus evident that apparent
destruction of toxic factors by extended steam treatment under pressure
was confirmed by animal tests.

Steam Stripping

Commercially produced enzyme-free rapeseed meals were placed in a
laboratory scale steam stripper which accommodated 300 g of meal, main-
tained a temperature of 110 C and permitted steam passage through
constantly revolving meal at a rate designed to yield about 12 ml of steam
condensate per minute (10). This treatment resulted in steady reduction
of isothiocyanate content resulting in almost complete removal by 2 hours.
About 10% of the oxazolidinethione remained after 3 hours of steam
stripping. As in the case of autoclaved meals, the bioassays confirmed the
chemically assayed toxicity and also confirmed the inability of added
myrosinase to depress growth response in mice fed meals steam stripped
at least 1 hour.

In studies designed to assess the nutritional value of the protein of
rapeseed meals treated by autoclaving or steam stripping the same authors
observed gradual deterioration in protein quality as time of steam treatment
was extended. In fact, meals that were autoclaved for 2 hours at 1.2 kg/cm2
did not support growth when used as the only protein source in an otherwise
adequate diet. These observations may reflect lysine destruction (24) (see
Chapter 2) but no lysine determinations were made.

Effects of pH and Temperature of Wet Enzyme-free and Enzyme-active
Meals on Subsequent Value of the Meals

Buffered solutions of pH 3, 6 or 9 were mixed with meals of B. napus
origin and stirred continuously for 1 hour at either 22 or 50 C. The wet
mash was then either filtered and washed twice with additional buffer
solution and then air dried or else dried without filtration (11).

Soaking the meal had little effect on chemically assayed toxicity in
the absence of myrosinase but removal of the filtrate eliminated over 80%
of the toxic compounds. By contrast, if myrosinase was present during the
conditioning period there was a loss of about ^ of the toxic material after
an hour's soaking at pH 3, \ at pH 6 and about § at pH 9, even though no
filtration was involved. When enzymatically-active meals were filtered
before drying those processed at pH 9 were slightly less toxic than those
treated at pH 3 and 6 but they all contained more mustard oils than did
the extracted residues resulting from enzyme-free meals. Conditioning tem-
perature had no effect.

In general, the bioassay results confirmed the chemical assays but
there was some evidence that enzymatic activity at pH 6 or 9 resulted in
lower quality meal than was indicated by isothiocyanate and oxazolidin-
ethione assays. Thus it appears that the more rapid destruction of mustard
oils at higher pH may simply have represented partial transformation into
related toxic compounds not detectable by the chemical methods employed.
It seems doubtful, therefore, that adjustment of pH for modification of
enzyme activity offers much promise in detoxification procedures.

Summary

The development of growth-inhibiting properties in rapeseed meal
appears dependent upon hydrolysis of thioglucosides into isothiocyanates
(3-butenyl and 4-pentenyl) and oxazolidinethione. The hydrolysis can be
effected by the enzyme myrosinase, normally present in unheated rapeseed
and more recently shown to occur in the gastrointestinal tract, where it is
produced by certain bacteria, especially by E. coli and A. aerogenes.

Oxazolidinethione appears to be the compound primarily, if not en-
tirely, responsible for goitrogenicity. However, it has been shown that
isothiocyanates can cyclize to form oxazolidinethione. This may account
for the rather similar effects of the two types of rapeseed compounds but
the nature of metabolic interference by isothiocyanates needs clarification.
These compounds have been shown to depress a number of metabolic
reactions but are claimed to be incapable of blocking thyroxine activity
once the hormone has been released from the thyroid. Whatever the final
explanation may be, the variable responses obtained from dietary supple-
mentation with iodine, iodinated casein and thyroxine indicate that the
action of the rapeseed compounds is more complicated than interference
with thyroxine synthesis or release. Thus it is of special interest to recall
the postulation that natural antithyroid compounds may exist which may
reduce the efficiency of circulating thyroxine, thereby depressing metabolism,
leading to increased production of TSH and to development of goiter.

Methods of processing rapeseed in Canada result in production of
myrosinase-free rapeseed meal containing unhydrolyzed thioglucosides.
Such meal apparently is free of most of the undesirable properties if

myrosinase is not reintroduced by other dietary ingredients or by intestinal
bacteria. The potential antithyroid activity can be markedly reduced by
heating, as revealed by the findings that most of the thioglucosides can be
destroyed by 2 hours of either autoclaving at a steam pressure of 1.2
kg/cm2 (17 lb/inch2) or steam stripping at 110 C. Autoclaving resulted in
severe damage to protein quality but steam stripping showed promise as a
means of alleviating the risk of thioglucoside hydrolysis during digestion
in the animal body.

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CHAPTER 5. FEEDING VALUE OF RAPESEED MEAL FOR

RUMINANT ANIMALS

F. Whiting, Research Coordinator (Animal Nutrition)
Research Branch, Canada Department of Agriculture, Ottawa

Introduction

Rapeseed meal is a relatively new protein supplement for ruminant
animals in Canada, although it has been used extensively in other parts
of the world for many years. It was regarded with some disfavor among
cattle and sheep producers until fairly recently because it was considered
to be unpalatable and to have certain growth-depressing and goitrogenic
effects when fed liberally. However, as discussed in Chapters 1 and 2, the
varieties of rape (largely Polish type, Brassica campestris) grown in
Canada now contain less of the glucoside oxazolidinethione and the method
of extracting the oil from the seed has changed largely from expeller to
solvent extraction. The enzyme myrosinase, which is present in rapeseed
and which splits the glucosides into the active goitrogenic substances,
requires moisture for this reaction {see Chapter 4). In modern processing,
the enzyme is destroyed in initial processing by steam heat and the goitro*
genie factors are left bound in the original glucoside complex.

Considerably less detailed research has been conducted with ruminant
animals on the digestibility, acceptability, efficiency of utilization, and com-
parative value of rapeseed meal than with pigs, poultry and laboratory
animals. Because ruminant animals have not been so adversely affected by
the so-called goitrogenic factors may be a reason (4, 5, 6). It had been
generally considered that rapeseed meal was less palatable and less readily
digestible than many of the other more commonly used high-protein meals
of plant origin (e.g., soybean, sunflower, linseed meal). This review is a
critical evaluation of rapeseed meal in comparison to other high-protein
meals for ruminant animals.

Rapeseed Meal for Young Ruminant Animals (Birth to 6 Months)

Very little detailed information is available on the value of rapeseed
meal for young calves and lambs in comparison with other extracted meals
from oilseed plants. Burkitt (8) reported that lambs digested a rapeseed
meal - grass hay ration to the same extent as a linseed meal - grass hay
ration. The rapeseed meal was not as palatable, initially, as the linseed
meal. Clark and Bezeau (10) fed three groups of Holstein dairy calves

limited whole milk (3.6 kg/day) to 28 days of age along with alfalfa hay
and a calf starter containing 10% linseed meal to one group, 10.4% expeller-
extracted rapeseed meal to a second group, and 10% solvent-extracted
rapeseed meal to a third group. The starter and alfalfa were feu until the
calves were 16 weeks old. Rapeseed meal made up about 6% of the drv
matter of the total ration. Although the calves initially did not eat the
starter containing rapeseed meal as well as that containing linseed meal,
there were no differences between groups in their consumption of starters
or rate of growth to 16 weeks of age. Palmer (19) reported that one group
of ram lambs weaned at about 5 months of age and offered rapeseed meal
ad libitum plus native pasture did not consume the rapeseed meal as readily
as did a group offered linseed meal. However, no abnormal symptoms were
noted among the lambs fed the rapeseed meal and the two groups gained
the same weight.

Hornoiu and Cadantu (13) stated that rapeseed meal was unpalatable
to cattle and sheep but that they would consume large quantities of it.
They recommended limiting milk cows to 0.5 kg daily, young cattle and
adult sheep to 0.3 kg daily and young sheep to 0.2 kg dailv although both
calves and sheep would consume up to 0.7 kg daily. It is not stated clearly
whether this recommendation is based on experimental evidence or on their
observations among livestock fed these amounts.

Rapeseed Meal for Growing and Fattening Animals

Seale (21) compared linseed meal, sunflower meal, mustard seed meal
and rapeseed meal when these meals made up 8 to 10% of a grain mixture
for fattening steers. The grain mixture was fed ad libitum after the first
6 weeks. The experiment continued for 140 days. Mature prairie hay was
fed as roughage. At the beginning of the feeding period the animals which
were fed the grain mixture containing rapeseed meal and mustard seed meal
did not consume their rations as promptly as those fed the other meals.
The group which was fed linseed meal gained an average of 0.98 kg per day,
and the other three groups gained an average of 0.86 kg per day. There
was no difference in efficiency of feed utilization between the groups re-
ceiving sunflower seed meal, rapeseed meal or mustard seed meal.

Burkitt et al. (9) fed pregnant beef cows, yearling cattle, and weaned
calves low protein roughages (grass hay and wheat straw) supplemented
with 0.4 kg of linseed meal or rapeseed meal per animal daily. Although
the rapeseed meal was relatively less palatable than the linseed meal, all
groups consumed their allotment of rapeseed meal and made gains similar
to those fed linseed meal. The animals consumed the linseed meal more
readily and quickly than those fed rapeseed meal. If the linseed meal and
the rapeseed meal had been fed ad libitum rather than in set amounts based
on need, the animals fed linseed meal would probably have consumed more
than those fed rapeseed meal. Masson (16) stated that rapeseed meal has

been icd satisfactorily at the Centre National de Recherche Zootechnique,
in Fiance, as 35% of the concentrate portion of the ration for fattening
steers (4 kg of concentrate was fed daily per animal). He emphasized that
the meal should be dry when fed and that it should be introduced into the
ration gradually.

Rapeseed Meal for Breeding Animals and for Reproduetion

Bell and Weir (4) fed four groups of 22 ewes each during pregnancy
with alfalfa and four groups with marsh hay (predominantly Carex
species) . One group of those fed alfalfa and one group of those fed marsh
hay received 0.2 kg daily of one of the following supplements: linseed meal,
rapeseed meal and mustard seed meal, one lot was fed alfalfa hay, and
one lot was fed marsh hay without protein supplement. The ewes fed the
rapeseed meal and mustard seed meal consumed their meals less rapidly than
those fed linseed meal but always consumed their daily allotment. The
three meals were equally effective in terms of weight gain of the ewes and
birth weight of the lambs. No thyroid enlargements were noted among the
ewes or the lambs from ewes fed rapeseed meal.

Bezeau et al. (7) fed rations which contained 10 and 20% rapeseed
meal and 10 and 20% linseed meal to groups of pregnant and lactating
ewes in comparison with similar groups fed no protein supplement. The
rations were composed of 50% chopped grass hay and 50% pelleted grain
mixture containing the rapeseed or linseed meal. The hay and grain mix
were fed separately. In the second experiment, rations containing 10, 20
and 30% rapeseed meal were compared writh one containing 10% linseed
meal. The rapeseed meal was from a mixture of summer and summer turnip
varieties (Brassica napus and B. campestris) , extracted by the expeller
process. It contained 2.09 mg of isothiocyanates and 2.41 mg of oxazo-
lidinethione per g of meal. No palatability problem was encountered when
rations containing 10 and 20% rapeseed meal were fed but there was a
problem with the ration containing 30% rapeseed meal. There were no
important differences betwTeen the groups fed rations with 10 and 20%
linseed meal and 10 and 20% rapeseed meal in terms of weight gains, and
wool production of the ewes and in birth weight and growth of the lambs.
The ewes fed the ration containing 30% rapeseed meal consumed less feed
than those fed the other rations, gained less weight, produced less wool
and smaller lambs that gained less rapidly. No enlarged thyroid glands
were noted among any of the ewes or lambs.

Rapeseed Meal for Milk Produetion

Jarl (14) fed cows 2.5 kg daily of an oilcake mixture containing 0, 25
and 50 to 60% rapeseed meal. The average daily consumption of rapeseed
meal was 1.2 to 1.4 kg when the oilcake mixture contained 50 to 60% rape-

seed meal. This represented about 9% of the dry matter intake. The rape-
seed meal used in these experiments contained an average of 1.6% ether
extract, 36.6% protein and 0.17% mustard oil. The cows produced an
average of 16 kg of 4% fat-corrected milk daily. The cows that were fed
0 and 25% rapeseed meal in the oilcake mixture produced 0.5 kg more
milk daily than the cows that received 50 to 60% rapeseed meal in the
oilcake mixture. The cows that received rapeseed meal produced milk of
slightly lower fat content, but gained more weight than the cows that
received no rapeseed meal. The fat produced by cows receiving rapeseed
meal was of higher iodine number than that by cows receiving no rapeseed
meal. Palatability of the rapeseed meal was not a problem as soon as the
cows became accustomed to it. The author stated that Swedish rapeseed
meal was a good high-protein concentrate for dairy cows and could be
fed at a daily amount of at least 2 kg per cow but that it should always be
fed dry.

Seale (20) fed two groups of six milking cows, 3 to 5 months postpartum,
a ration of hay and grain mixture which contained either 20% rapeseed
meal or 20% linseed meal. The daily amount of hay fed to each cow was
determined by her body weight and the amount of grain mixture by her
milk production. Each experimental period lasted 21 days and was preceded
by a 10-day preliminary period. Average daily milk production during
the experimental period was 11 kilograms. When the cows received the
ration containing rapeseed meal they produced about 0.2 kg more milk per
cow daily (not statistically significant) of the same butterfat content.
There was no difference in palatability between the rations or in the taste
and odor of the milk produced.

Nordfeldt (18) compared rapeseed meal of low and high fat content
(1.6 and 7.0%) with soybean meal when fed to dairy cows in digestion and
feeding experiments. There was no difference between groups in milk pro-
duction. Feeding rapeseed meal at a daily rate of 1.8 kg resulted in a small
but significant increase in iodine number of the fat. There was no difference
in odor or taste of the milk produced. Rapeseed meal was as palatable
as soybean meal. The low fat rapeseed meal used contained 37.9% protein,
9.9% fiber and 0.4% mustard oil. The author suggested that feeding 1.5 kg
per cow daily is practical.

Homb et al. (11) fed two groups of 11 cows during an 11-week period
the same rations except that one group received a concentrate containing
5% rapeseed meal and the other group a concentrate containing 5% lin-
seed meal. There were no significant differences between groups in milk
yield, condition of the animals or consistency of the feces. The inclusion of
rapeseed meal in the concentrate mix did not taint the milk. In further
experiments (12) when groups of 12 cows were fed either 5 or 10% rapeseed
meal (250 and 395 g daily, respectively) in the concentrate mix or an

equivalent amount of herring meal or soybean meal there was no difference
in milk yield, fat content of the milk or weight gain of the cows. The
iodine number of the milk fat increased slightly when rapeseed meal was
fed. Rapeseed meal had no effect on the palatability of the milk.

In an experiment at the University of Alberta, Asplund (1) fed rations,
during 12-week periods, to milking cows in which rapeseed meal made up
0, 10 and 20% of the dry matter content of the total ration. All rations
contained the same protein content (rapeseed meal replaced linseed meal
in the ration). Expeller-processed meal was used. Some cows rejected at
first the concentrate mix containing rapeseed meal but all consumed their
daily allowance after the first week. The cows that received 10% rapeseed
meal produced as much milk as those that received linseed meal, but those
that received 20% rapeseed meal declined in milk production almost twice
as fast as the controls (46 vs 26% over the 12-week period). Average pro-
duction was 16 kg per day. There was no difference between groups in the
flavor of the milk. Feeding rapeseed meal at 20% of the total ration did
not affect the protein-bound iodine content of the blood during an 11-week
period. In a further experiment (2,3) a concentrate mix containing either
10% linseed meal or 10% rapeseed meal was fed to dairy cows on pasture
at 1 kg per 6 kg of milk or 1 kg per 12 kg of milk produced during a 13-
week period. The cows produced an average of 21 kg of milk daily. The
concentrate mix which contained rapeseed meal was as palatable as that
which contained linseed meal. There was no difference in milk production
caused by the substitution of rapeseed meal for linseed meal. Solvent-
extracted rapeseed meal was used in this experiment.

Witt et al. (23) fed 22 milk cows, with an average milk production of
19 kg, a ration in which the concentrate mix contained 25% rapeseed
meal. Daily intake of the rapeseed meal which contained 1.1% fat was
between 1.25 and 1.36 kilograms. The ration which contained rapeseed meal
was well accepted by the cows and increased the average daily milk yield
per cow by 0.4 kg with no adverse affect on the fat content.

Larsen (15) reported that rapeseed meal which did not contain poison-
ous seeds or which did not contain large quantities of mustard oil could be
used successfully in limited amounts as a feed for milk cows. He further
stated that rapeseed meal from seed grown in Europe had a mustard oil
content which seldom exceeded 0.20 to 0.25 percent. Meal prepared from
such rapeseed is safe as a feed for milk cows. In early Danish experiments,
dairy cows had been fed 3 to 4 kg of rapeseed meal daily with no ill effects
except diarrhea. In more recent experiments cows received as much as
2.2 kg of meal daily. Although some difficulty was experienced initially in
getting the cows to consume this amount of rapeseed meal (rapeseed meal
made up 40% of a concentrate mixture), the cows consumed the quantity
given to them after the first week.

97386—5

Masson (16) stated that rapeseed meal had been used satisfactorily as
30% of the concentrate portion of rations for milk cows. Four kg of con-
centrate was fed daily. He cautioned that rapeseed meal should be intro-
duced gradually into a ration.

Although ruminant animals do not seem to be affected by the potential
goitrogenic factors in rapeseed meal to the same extent as poultry, pigs
and laboratory animals, the question has been raised as to whether these
factors can be transferred from the feed to the milk of dairy cows. Virtanen
et al. (22) in Finland, studied this question and concluded that only
approximately 0.05% of the (-)-5-vinyl-2-oxazolidinethione (previously
known as (l)-5-vinyl-2-thiooxazolidone) contained in the ration was found
in the milk, an amount so small that milk from cows fed large quantities of
rapeseed meal rich in oxazolidinethione would have insignificant amounts.
Similar results were obtained with thiocyanates. Virtanen et al. (22) point
out that the reason for this was that the goitrogens were destroyed in the
rumen and not absorbed into the blood stream. This may explain why
ruminant animals have not shown enlarged thyroid glands or other symp-
toms when fed fairly large amounts of rapeseed meal.

Composition and Digestibility of Rapeseed Meal

Data on the chemical composition of rapeseed meal are shown in Chap-
ter 3. Although the varieties of rapeseed grown in many areas of the world
have changed in recent years and the method of processing the meal has
changed almost entirely from an expeller to solvent extraction (at least
in Canada and Western Europe) , the digestibility of rapeseed meal has not
changed appreciably. Nehring and Schramm (17) reported that rapeseed
meal contained 29.2% digestible protein and linseed meal 30.7% (no diges-
tibility coefficients listed), whereas the corresponding starch values were
60.7 and 58.0 percent. Bezeau et al. (7) found that the digestibility of the
dry matter and protein was higher in a ration which contained 20% linseed
meal than in a ration which contained 20% rapeseed meal (64 vs 61%
for dry matter and 73 vs 66% for protein) . The two rations
contained the same percentage of protein. Jarl (14) reported digestibility
coefficients for the organic matter of rapeseed meal as 76%, ether extract
98%, crude fiber 25%, nitrogen-free extract 78% and crude protein 83 per-
cent. The rapeseed meal that was fed in Jarl's experiment contained 1%
ether extract, 0.17% mustard oil and 35% protein. Nordfeldt (18) reported
that dairy cows fed rapeseed meal containing 37.9% protein, 1.7% fat, and
9.9% crude fiber digested approximately 76% of the organic matter and
85% of the protein. Burkitt (8) compared the digestibility of a grass hay -
rapeseed meal ration to a grass hay - linseed meal ration when fed to
lambs (average wt 34 kg). Both rations contained 11.4% protein. There
was no significant difference in the digestibility of the dry matter of the
rations or the individual nutrients in the two rations.

General Recommendations

As pointed out in the Introduction to this chapter, rapeseed meal
produced by solvent extraction and by preheating to destroy myrosinase
activity is a much superior meal to that common in Canada and many
countries of the world 10 to 20 years ago. Introduction of new varieties of
rape also has had an effect on the quality of the meal produced. Even
when the meals produced in North America and Europe 20 or more years
ago were icd to ruminant animals very few adverse effects were noted.
Present evidence as reviewed here indicates that solvent-extracted rape-
seed meal similar to that produced in Canada can be considered to be
equivalent in nutritional value on an equivalent protein basis to other
high-protein meals of plant origin such as linseed and soybean meals when
it makes up to 10% of the total dry matter of the ration. Since only under
unusual circumstances will rapeseed meal be fed in amounts exceeding
10% of the total ration no adverse effects on gains, milk production or
reproduction should be expected. Rapeseed meal when forming more than
10% of the total ration, or a component of part of the ration, may be less
acceptable initially to ruminant animals of all ages than soybean, linseed
or sunflower meals. However, ruminant animals become accustomed to rape-
seed meal fairly rapidly and no palatability problems are usually en-
countered after approximately one week from when it is introduced
into the ration.

References

1. Asplund, J. M. 1961. Univ. Alberta Press Bull., 40th Ann. Feeders' Day, p. 18.

2. Asplund, J. M. 1962. Univ. Alberta Press Bull., 41st Ann. Feeders' Day, p. 6.

3. Asplund, J. M. 1964. Private communication.

4. Bell, J. M., and J. A. Weir. 1952. Sci. Agr. 32:496.

5. Bell, J. M. 1955. Can. J. Agr. Sci. 35:242.

6. Bell, J. M. 1961. Univ. Saskatchewan 6th Ann. Stockman's Day Rep., p. 16.

7. Bezeau. L. M., S. B. Slen and F. Whiting. 1960. Can. J. Animal Sci. 40:37.

8. Burkitt, W. H. 1951. Montana Agr. Exp. Sta. Circ. 193.

9. Burkitt, W. H., J. J. Urick, R. M. WTilliams and F. S. Willson. 1954. Montana

Airr. Exp. Sta. Bull. 499.

10. Clark, R. D., and L. M. Bezeau. 1964. Private communication.

11. Homb, T., I. 0reed and T. Wolden. 1958. Tidsskr. Norske Landbruk 65:253.

12. Homb, T., I. 0rccd and T. Wolden. 1961. Norges Landbruksh^gsk F6ringsfors0k

Beretn \r. 103, p. 31.

13. Hornoiu, M., and L. Cadantu. 1960. Lucrarile Stiint. Inst. Cercetari Zooteh. 18:103.

11. Jarl, F. 1951. Kungl. Lantbrukshogskolan och Slatens Lantbruksforsok Statens
Husdjursforsok Meddelande Xr. 45.

15. Larsen, J. B. Saetryk af en artikel fra Landsbladet Udgivel at" De samverkende

danske Landboforeninger (undated reprint).

r>7

97386— 5i

16. Masson, C. G. Centre Technique Interprofessionnel des Oleagineux Metropoli-

tans, Paris (undated mimeograph).

17. Nehring, K., and W. Schramm. 1951. Arch Tierernahr. 2:81.

18. Norfeldt, S. 1958. Kungl. Lantbrukshogskolan och Statens Lantbruksforsok Statens

Husdjursforsok Meddelande Nr. 66.

19. Palmer, A. E. 1946. Prog. Rep., Dominion Exp. Sta., Lethbridge, Alberta, 1937-

1946, p. 54.

20. Seale, M. E. 1952. Univ. Manitoba 2nd Ann. Livestock Day Rep., p. 1.

21. Seale, M. E. 1952. Univ. Manitoba 2nd Ann. Livestock Day Rep., p. 11.

22. Virtanen, A. I., editor, (a collection of papers by A. I. Virtanen, R. Gmelin, M.

Kiesvaara, M. Kreula, E. Piironen, M. Saarivirta and P. Vilkki). 1963. Bio-
chemical Inst., Helsinki.

23. Witt, M., F. W. Huth and W. Hartmann. 1959. Z. Tierphysiol. Tierernahr. Fut-

termittelk. 14:175.

CHAPTER 6. FEEDING VALUE OF RAPESEED MEAL FOR SWINE

J. P. Bowland, Professor of Animal Nutrition
University of Alberta, Edmonton

Introduction

As swine are monogastric animals, they must be supplied with a
source of protein that meets both their quantitative requirements for pro-
tein and their qualitative requirements for essential amino acids. The
amino acid composition of solvent-extracted rapeseed meal as compared
with other vegetable protein sources is given in Chapter 3. When these
composition data are compared to the amino acid requirements of the
young pig [U.S. N.R.C. Nutrient Requirements for Swine (27) ] the poten-
tial quality of rapeseed meal is found to be similar to that of soybean meal.
There is the suggestion, however, from some early studies with pigs, that
the nutritional value of rapeseed meal may not parallel its potential based
on average analysis. These experiments will be discussed later in this
chapter.

In recent years there has been a major change in processing methods
used for rapeseed meal (see Chapter 2) . Meals that are now available
are either solvent extracted or solvent extracted following partial expeller
extraction. As discussed in Chapters 2 and 3 the present meals have a higher
level of amino acids, particularly lysine, than former meals. In addition
the average protein, fat and crude fiber of 40.5, 1.1 and 9.3% respectively
from solvent meals are markedly different to average values given
by Morrison (26) . Therefore the actual value of rapeseed meal for swine
feeding must be considered in relation to the meals at present available.

Starting Rations for Pigs up to 25 kg Liveweight

Feed Intake

A major criterion in evaluating rations for creep feeding, pre-starting
and starting of pigs up to 8 to 10 weeks of age or 25 kg in weight is the
provision of a ration that is acceptable and therefore consumed at high
levels to provide a high energy intake. It has been observed that rapeseed
meal is often not liked by livestock, probably because of its sharp bitter taste
(26) . Studies with young pigs have given variable results regarding accept-
ability or palatability of rations containing rapeseed meal. Bowland (8)

noted that when an alternate ration was available, pigs did not accept
pre-starter rations containing 2 to 10% of expeller-processed rapeseed meal
of either Argentine (Brassica napus) or Polish (Brassica campestris) type.
When pigs at 3 weeks of age, averaging 6 kg in weight, were offered a ration
containing the same Argentine-type meal with no alternative available
there was no evidence of appetite depression (9,20). The group-fed pigs
receiving 10% rapeseed meal in the ration consumed 0.69 kg per day as
compared to 0.66 kg per day for those receiving a ration with soybean
meal substituted at an equivalent protein level. In later studies (12,23), with
group-fed or individually-fed pigs weighing 9 to 23 kg there was no signifi-
cant influence on feed consumption when all of the soybean meal in a basal
starting ration containing 13% soybean meal was replaced by isonitroge-
nous levels of solvent-extracted Polish-type rapeseed meal.

Seale (32) found that inclusion of 13 to 26% rapeseed meal to replace
\ or all of the linseed meal in a ration for pigs from 18 to 36 kg in weight
had no adverse effect on feed consumption. In more recent studies at the
University of Manitoba (34) rapeseed meal containing 5.15 mg isothio-
cyanate and 3.45 mg oxazolidinethione per g of meal was fed to 14 kg
pigs for a 3- to 4-week period. This rapeseed meal was compared as a
replacement on a protein-equivalent basis for 50 to 100% of the protein
contributed by soybean meal which represented 10.4% of the ration. There
was a depression in average daily feed intake from 1.11 kg per day for
the soybean meal ration to 0.90 kg per day when rapeseed meal replaced
100% of the soybean meal.

Lack of palatability does not seem to be a major factor affecting
the use of rapeseed meal in starting rations. The addition of 10% or over
of rapeseed meal to the ration of young pigs may reduce ration acceptabil-
ity as evidenced by lower feed consumption, but this is a level above that
recommended in normal ration formulation for young pigs.

Rate of Gain and Efficiency of Feed Utilization

As discussed by Clandinin et al. (14) and others, and as outlined in
Chapters 2, 3 and 4, the growth promoting value and goitrogenic properties
of rapeseed meal are influenced by factors such as variety of the seed and
environmental conditions under which it is grown, processing methods, and
physiological aspects such as sex and age of animals.

In studies at the University of Alberta (9,20) with expeller-processed
meal, average daily gain was not significantly depressed when group-fed
pigs from 6 to 16 kg liveweight received 2 or 10% rapeseed meal in substi-
tution for soybean meal. With individually-fed pigs of similar weight, rate
of gain was depressed 0.06 kg per day when 10% rapeseed meal was fed.
Efficiency of feed utilization (kg feed per kg gain) was not influenced in this
study.

In a later experiment with solvent-extracted rapeseed meal (12,23),
the substitution of rapeseed meal for 25% of the soybean meal in the

ration had no effecl on rate of gain for group-fed pigs from 9 to 23
kg liveweight l)iit 50 or 100% substitution reduced rate of gain 0.07 and
0.10 kg per day respectively. The addition of 0.2% L-lysine to the
ration containing the highest level of rapeseed meal did not improve
gain. Efficiency of feed utilization was not influenced by any level of rape-
seed meal.

In Seale's experiment (32) rapeseed meal did not influence gain or
feed/gain ratio of pigs from 18 to 36 kg liveweight. In a later Manitoba
study (34) with younger pigs there was a depression in rate of gain when
rapeseed meal replaced 50 or 100% of soybean meal in the ration. This
reduced gain was related to feed consumption so that efficiency of feed
utilization was not adversely affected by rapeseed meal. Rates of gain
on the rapeseed meal-containing ration were similar to those obtained when
>unflower meal was substituted at equivalent levels but efficiency of feed
utilization was superior for the rations containing rapeseed meal.

With young weanling or pre-weanling pigs from 3 weks of age up to
weights of 25 kg, the rate of gain may be depressed when rapeseed meal
is compared with soybean meal as a protein supplement at levels above
4 to 5% of the total ration, although levels of rapeseed meal up to 10%
of the ration are normally acceptable. Any growth depression occurring is
usually closely related to reduced feed intake and efficiency of feed utiliza-
tion is not adversely influenced by substitution of rapeseed meal for soy-
bean meal in the ration.

Growing and Finishing Rations for Market Pigs
from 25 to 90 kg Liveweight

Feed Intake, Gain and Feed Conversion

Studies with rapeseed meal as a protein supplement for growing and
finishing pigs above 25 kg in weight are more extensive than those with
younger pigs. As mentioned in the Introduction to this chapter, many of
the early studies are largely of historical interest because of the changes
in processing methods in recent years.

In studies in Germany in 1937, Frolich and Haring (18) satisfactorily
fed up to 200 g of rapeseed meal per head per day to young growing pigs,
but reported that the meal was unsatisfactory for finishing pigs. However,
in a second study (19), the same authors indicated that rape meal could
replace a portion of the fishmeal in the ration of fattening pigs. For a live-
weight gain of not less than 600 g per day, they recommended that the
daily amount of rape meal must not exceed 150 g if the mustard oil content
is low (0.11-0.13% ) or 100 g if it is high. In a small-scale experiment, Cook
(15) in 1941 found that the substitution of rapeseed meal for half the meat
meal in a standard ration gave poor results.

In 1952, Scale (32) compared expeller- extracted rapeseed meal and
linseed meal as the sole sources of supplemental protein in pig rations based

on oats, wheat and barley. From 36 kg to market weight of 91 kg, pigs
receiving rapeseed meal as the sole source of protein made slower and less
efficient gains than those receiving linseed meal, even though rapeseed meal
had no effect on performance when fed up to 36 kg liveweight. When rape-
seed meal replaced only half of the linseed meal, the gain and feed/gain
ratio were comparable to those obtained with linseed meal. The author
suggests that inclusion of rapeseed meal may have decreased palatability of
the ration. However, daily feed consumption varied by only 0.1 kg per
day between lots. The pigs receiving rapeseed meal consumed their feed
more slowly and were inclined to waste feed.

In 1953 Seale (33) reported further studies to determine the optimum
level at which rapeseed meal should be incorporated in a protein supplement
used with an oat-wheat ration. The 35% crude protein supplement con-
tained 20% meat meal, 20% alfalfa meal and 60% linseed meal with rape-
seed meal replacing ^, § or all of the linseed meal. The results indicated
that rapeseed meal can be included as a replacement for linseed meal in a
protein supplement of the type used without significant reduction in feed
intake, rate of gain or efficiency of feed utilization.

In studies by Nordfeldt et al. (28) rapeseed meal was evaluated with
isocaloric and isonitrogenous diets fed to pigs. Daily gain was not signifi-
cantly reduced when rapeseed meal was fed as 13.0, 9.5, 8.0 or 0% of the
ration from 30, 40, 50 and 75 kg liveweight respectively. In a second experi-
ment both untreated and water-extracted rapeseed meals were fed at levels
of 17.5, 10.0, 7.5 and 3.1% of the ration when pigs reached 30, 40, 50 and
90 kg liveweight. Growth depression occurred in this experiment but was
less for the water-extracted meal.

Clausen in Denmark, as described by Fevrier (16), reported a marked
decrease in feed consumption in growing pigs receiving rapeseed meal and
milk, rapeseed meal and meat meal or straight rapeseed meal in compari-
son with milk. These results were based on 24 pigs per lot started on experi-
ment at 24 kg liveweight. Rate of gain and efficiency of feed utilization
were depressed in the rations containing rapeseed meal as compared to
the control ration containing milk as the source of supplemental protein.

In 1957, Fevrier (16) reported on a series of experiments in which
swine were used as experimental animals to test the supplemental value of
four lots of rapeseed meal, part of which was treated by the Andre process,
which involved a combination of heat and of hot water extraction by use of
active steam. The rations contained 10 to 25% rapeseed meal with the
protein balanced with 5% meat meal and, in some cases, peanut meal.
Gain was lower when the highest level of rapeseed meal was fed. The hot
water treatment was not generally effective. Further studies were con-
ducted using meal that was more intensively steam-treated than in the
former case. There was a marked improvement in feed intake, average
daily gain and feed conversion from the meals that wrere more intensively
treated but the gain was still inferior to that expected from other meals.

Hussar and Bowland (20) fed 2 or 10% expeller-extracted Argentine-
type {B. napus) rapeseed meal to either group-fed or individually-fed
market pigs and found that the 10% level of the meal depressed rate of
liveweight gain and in some cases reduced efficiency of feed utilization.
Feed consumption was not adversely influenced by the levels of meal used
in the diets. The 2% level of rapeseed meal did not exert any demonstrable
effects on any criteria measured.

In studies with solvent-extracted rapeseed meal (12,23), the meal was
substituted on an equivalent protein basis for 0 to 100% of the soybean
meal in diets for pigs. At the highest level of feeding, rapeseed meal repre-
sented 66 to 76% of the total supplemental protein (15.6% of the total
ration for growing pigs and 9.6% of the ration for finishing pigs) . Replace-
ment of 25% of the soybean meal by rapeseed meal did not influence feed
intake, rate of gain or efficiency of feed utilization but when 50 or 100%
of the soybean meal was replaced by rapeseed meal the rate of gain and
efficiency of feed utilization were depressed for group-fed pigs from 23
to 50 kg liveweight but not for individually-fed pigs. Addition of 0.2% L-
lysine to the ration containing 100% rapeseed meal failed to influence rate
of gain and significantly depressed efficiency of feed utilization.

Myrosinase Activity in the Meal

The enzyme myrosinase may play a part in the growth-depressing
properties of some samples of rapeseed meal. It is pointed out in Altschul's
review (1) that this enzyme catalyzes decomposition of sinigrin and sinal-
bin with the formation of mustard oils. In a recent paper Bell (6) has
studied the feeding value for growing-finishing swine of myrosinase-free
solvent-extracted rapeseed meal and of the effect of adding a source of
myrosinase to diets containing this new-process meal. The meal was of B.
campestris L. origin and although free of active myrosinase retained most
of its original complement of thioglucosides.

The use of either 5 or 10% of this rapeseed meal significantly de-
pressed feed intake and rate of gain from 23 to 46 kg liveweight while
a level of 5% meal in the finishing ration fed above 46 kg liveweight had no
effect on swine performance. Growth depression closely reflected feed intake
levels, hence palatability of the rapeseed meal may have been involved.
When ground rapeseed screenings were added as a source of myrosinase
there was three times as much growth depression during the growing period
as occurred in the absence of rapeseed screenings (6). Growth depression
also occurred in the finishing period when rations contained 5% rapeseed
meal. The author mentions that the results of this experiment confirm
previous findings in vitro and with mice. In practice it must be recognized
that there may be a problem in formulating rations free of external sources
of myrosinase even if the rapeseed meal is itself processed so as to be free
of active myrosinase. As discussed in Chapter 4, the enzyme myrosinase
may also occur in the gastrointestinal tract where it is produced by
bacteria.

Although results of experiments have varied, the general strength of
evidence is that rapeseed meal, particularly solvent-processed meal, may
replace up to half the supplemental protein for growing and finishing pigs
with little or no adverse effect on rate of gain and efficiency of feed utiliz-
ation. This recommendation supports that of Bell (4) in his review of 1954
and of the 1963 publication on "Oil and oilmeal from Canadian rapeseed"
(7).

Carcass Characteristics

The addition of rapeseed to the ration of market pigs has had no
consistent influence on carcass lean and fat measurements. In a Canadian
study (32) in 1952, carcass grades for pigs receiving rapeseed meal in sub-
stitution for linseed meal were improved but the author mentions that this
may be attributable to either the slower gain in the finishing period or the
approximately 4 kg per pig lighter market weight of the rapeseed meal
supplemented pigs. In a second study (33) in 1953, rapeseed meal was
included as a replacement for up to 100% of the linseed meal (60% of the
total protein supplement) with no effect on carcass quality as evidenced by
Canadian grades or Advanced Registry (now ROP) carcass measurements
and score.

Bowland (9) and Hussar and Bowland (20) observed only a limited
influence on carcass quality when 10% rapeseed meal was included in the
ration and no effect when 2% rapeseed meal was added to the ration of
growing and finishing pigs. Loin area was significantly reduced in individu-
ally-fed pigs receiving 10% rapeseed meal in the ration but this effect was
not evident for group-fed pigs. There was also a trend toward shorter
carcasses from the pigs receiving 10% rapeseed meal even though they
were older at slaughter and might be expected to have longer carcasses.
The authors discuss results indicating that thiouracil-fed pigs have shorter
carcasses than control animals so that the carcass length of the rapeseed
meal-fed pigs might be related to thyroid changes resulting from rapeseed
meal consumption. In the experiment of Manns and Bowland (23) carcass
measurements and carcass grades were not significantly influenced by the
addition of solvent-extracted rapeseed meal as a replacement for up to
100% of the soybean meal in the ration. The pigs receiving 50 or 100%
rapeseed meal in replacement for soybean meal had 2.8 mm less backfat
than those receiving lower levels or no rapeseed meal.

Bell (6) observed little influence of myrosinase-free rapeseed meal
on carcass quality although loin area increased as the level of rapeseed
meal increased in the ration. Rapeseed screenings which provided a source
of myrosinase apparently depressed loin area.

The results of experiments with market pigs suggest that the levels
of rapeseed meal recommended as being satisfactory for growth and feed
conversion will have no adverse effects on carcass characteristics.

Reproduction and Lactation Rations

In his review in 1954, Bell (4) reported that there was insufficient data
on the use of rapeseed meal to formulate recommendations for breeding
stock in pigs. Morrison (26) after reviewing the information available
suggested that caution in use of rapeseed meal is necessary for pregnant
animals. In 1937, Frolich and Haring (18) reported that under certain
conditions up to 400 g rapeseed meal per. head per day was satis-
factory for nursing sows. For young sows over 60 kg liveweight an allow-
ance of 200 g rapeseed meal per day was recommended. Bell (5) obtained
unsatisfactory reproduction and lactation from gilts receiving 7% rape-
seed meal as a replacement for linseed meal. Number of pigs born alive,
birth weights and weaning weights were low for the litters from gilts
receiving rapeseed meal in the ration, with the worst results for those
receiving Polish-type (B. campestris) meal. The gilts receiving rapeseed
meal lost more weight between prior to farrowing and the end of lactation
than was lost by the control gilts.

The only recent studies on the use of rapeseed meal for reproduction
in pigs are those of Bowland (10) and Manns and Bowland (23) reported
in 1963. Solvent-extracted rapeseed meal was substituted for 0, 25, 50 or
100%- of the soybean meal in the rations from the time that gilts and boars
were 3 weeks of age to the end of the first reproductive cycle including lac-
tation. During gestation and lactation, 71% of the total supplemental
protein or 12% of the total ration was represented by rapeseed meal when
it replaced 100% of the soybean meal in the ration.

All gilts that farrowed and were receiving rapeseed meal in substitu-
tion for 0 or 25% of the soybean meal in the ration conceived in the first
oestrus period in which they were bred at a minimum age of 230 days.
There was difficulty in obtaining conception of gilts receiving the higher
levels of 50 or 100% rapeseed meal in substitution for soybean meal as
these gilts required an average of 2 to 2.5 oestrus cycles to conceive. Addi-
tion of 0.2% L-lysine to the ration containing the highest level of rape-
seed meal was of no benefit. In simultaneous studies with rats, poor repro-
duction and lactation were also encountered and these results with rats
have since been verified in a more detailed experiment (11). Kennedy and
Purves (22) have noted a delay in development of the ovaries of immature
rats ted rapeseed meal and Manns and Bowland suggest that a similar
effect may have been elicited with the gilts in their study.

The number of pigs born alive was normal but litter size and weaning
weights of the pigs at 5 weeks of age were low for gilts receiving rapeseed
meal in replacement for 100% of the soybean meal. These results suggest
lactational inadequacy.

Boars in all lots reached sexual maturity prior to 230 days of age
as judged by their breeding performance and by their ability to sire litters.

The authors (23) suggest that solvent-extracted rapeseed meal should not
be used at levels above 3% of the total ration of breeding females during
pre-gestation, gestation and lactation.

Digestibility and Utilization of Energy and Nutrients

In studies with swine, the digestibility of dry matter and energy and
the digestibility and utilization of protein have usually been similar with
rations containing rapeseed meal to those of rations containing other vege-
table protein supplements such as soybean meal and linseed meal. Rape-
seed meal contains an average of 9.3-15.5% crude fiber, which is higher
than that for most other vegetable meals, and this fiber might be expected
to lower dry matter and energy digestibility.

Fevrier (16) reported a dry matter digestibility coefficient of 75% and
a protein digestibility coefficient of 85% for Argentine-type {B. napus)
rapeseed meal fed to pigs. Hussar and Bowland (21) obtained no significant
effect on apparent digestibility of dry matter (average digestibility coeffi-
cient of 82%), energy (average of 81%) and nitrogen (average of 80%)
in pigs weighing approximately 7, 28 or 60 kg liveweight, and receiving
rations containing 0, 2 or 10% expeller-extracted rapeseed meal, with rape-
seed meal replacing soybean meal on an isonitrogenous basis. With the
younger pigs, the highest level of rapeseed meal did depress digestibility to
a non-significant degree, however. The 10% level of this same rapeseed meal
significantly depressed apparent digestibility of dry matter, energy and
nitrogen in rats. Retention of digestible nitrogen in pigs and rats was un-
altered by the rations fed. For example, 7 kg pigs receiving 10% rapeseed
meal (70% of the supplemental protein) retained 42% of the nitrogen
absorbed as compared to 41% retained for those receiving the basal diet
with rapeseed meal.

Manns and Bowland (24) observed a reduction in digestibility of dry
matter by 34 kg pigs receiving 100% rapeseed meal in substitution for
isonitrogenous amounts of soybean meal but no other significant changes
in digestibility when 25 to 100% rapeseed meal was substituted for soybean
meal. When rapeseed meal was substituted at the 100% level there was a
trend toward reduced digestibility of dry matter, energy and nitrogen with
finishing pigs and with gilts during gestation and lactation. A supplement of
0.2% lysine added to the ration containing the highest level of rapeseed
meal improved dry matter, energy and nitrogen digestibilities for pigs at
34 kg liveweight and during gestation and lactation. The cause of reduced
digestibilitv and retention in some cases when rapeseed meal was fed may
be related to thyroid activity (25) , but may also be related to levels and
availability of amino acids in the meal as evidenced by the improved
digestibility when supplemental lysine was fed.

The data (24) suggest that reduced gain and poorer efficiency of feed
utilization may be partly associated with lowered digestibility and reten-

tion of energy and nutrients. Fevrier (16) observed, however, that high-
temperature treatment of rapeseed meal lowered digestibility of the meal
but that the rate of gain of swine fed this meal was improved over those
fed meal processed at a lower temperature. He suggests that the harmful
factors in the meal that are removed by heat treatment have a greater
effect on performance than the reduced digestibility resulting from the ex-
cessive heat treatment.

In studies with solvent-extracted rapeseed meal of B. campestris origin,
and free of active myrosinase, Bell (6) obtained no reduction in digestibil-
ity of energy and protein when the meal was fed to growing and finishing
pigs. When ground rapeseed screenings were added as a source of myrosin-
ase there was evidence of a depression in digestibility coefficients for energy
and protein. Therefore the presence of the enzyme, myrosinase, may be
implicated in digestibility depression.

Goitrogens and Other Factors in Rapeseed Meal

As outlined in Chapter 4, rapeseed meal contains goitrogenic principles
which may be modified by processing procedures. It is also shown that rape-
seed meal may contain other potentially toxic factors. In the reviews by
Altschul (1) and Bell (4) it is suggested that the only satisfactory method
of counteracting the total effect of the factor (s) is to limit the use of the
meal.

Hypertrophy of the thyroid has been widely noted when rapeseed meal
is fed to pigs (16, 20, 25, 28, 32). Iodide and iodinated casein have been par-
tially effective against the rapeseed goitrogens. For example, Nordfeldt et
al. (28) found that 0.5 g iodinated casein per 100 kg body weight when
fed to pigs receiving rapeseed meal did not affect growth, but reduced thy-
roid enlargement. Intensive steam treatment of rapeseed meal has also im-
proved its feeding value for pigs (16).

Fevrier (16) observed that the rat behaved similarly to swine in rela-
tion to thyroid enlargement as well as general performance and that rats
might be useful as test animals. In studies at the University of Alberta
(20, 21, 23, 24, 25) it was also found that the rat and the pig generally re-
sponded very similarly to feeding of rapeseed meal at various physiologi-
cal stages in the life cycle.

Hussar and Bowland (20) conducted detailed histological examination
of the thyroid glands from market pigs at 89 kg liveweight. In pigs receiv-
ing 0, 2 or 10% rapeseed meal from 6 kg liveweight to slaughter, the thy-
roid glands weighed 5.9, 6.6 and 17.3 g respectively. At the 2% level
there was evidence of some increase in cellular components and limited
glandular hypertrophy, while at the 10% level there was a marked
increase in cellular components and glandular hypertrophy evident. Manns
et al. (25) observed moderate hypertrophy of thyroid glands of market
pigs that received rapeseed meal. Based on concurrent studies with rats and

previous observations of Kennedy and Purves (22) they suggest that pigs
adapt to the goitrogen in rapeseed meal so that there is a decrease in thy-
roid hypertrophy relative to body weight after an initial period of thyroid
response (see Chapter 4).

A change in the size of other organs has also been reported when
rapeseed meal is fed. For example, enlarged livers and kidneys in market
pigs were observed by Nordfeldt et al. (28) and Scale (32) and enlarged
livers in sows and market pigs were noted by Bowland et al. (13).

Manns et al. (25) found that rate of gain and efficiency of feed
utilization in pigs fed rapeseed meal appeared to be related to the degree
of thyroid malfunction. On the other hand there is not always a definite
correlation between thyroid enlargement and growth depression when rape-
seed meal is fed (28).

The formation of mustard oils in rapeseed meal has been suggested as
a digestive tract irritant (18, 19, 26). Frolich and Haring (18, 19) reported
that digestive tract disturbances could be alleviated by feeding charcoal.
Seale (32) noted no symptoms of digestive disturbances in his study with
rapeseed meal. Although not specifically studied by other research workers,
the results of most experiments do not suggest digestive disturbances. It is
of interest, however, that Anderson and Hurwitz (2) observed that in in
vitro studies allyl isothiocyanate was effective against Ascaris lumbricoides
(roundworm) of swine.

Vitamin A storage per g of liver and in the total liver was increased
for sows receiving rapeseed meal as a replacement for soybean meal in
the ration whether or not the rapeseed ration was supplemented with
0.2% L-lysine (14). This increased storage may indicate a reduced
metabolic utilization of vitamin A as suggested by Bamji and Sundaresan
(3) and others. Pigs killed at 90 kg liveweight failed to show a similar
increased liver storage of vitamin A when rapeseed meal was fed.

Rapeseed Oil

{See Chapter 1 for further discussion)

Supplemental fats or oils are being added to pig rations as a method
of increasing energy levels of the ration, particularly for young pigs. A
series of Finnish studies (29, 30, 31) have compared rapeseed oil with
soybean oil as an addition to swine rations. Digestibility of both oils was
found to be approximately 100 percent (29). This agrees with studies by
Franke (17) in Germany in which a digestibility coefficient of 99.2% was
obtained for rapeseed oil in swine rations. The Finnish work reported a re-
duced rate of gain for pigs fed rapeseed oil as compared to soybean oil with
both oils added to supply 28% of the caloric intake in the feed of weanling
pigs. Both oils resulted in a mild interstitial myocarditis and gastritis, which
was not evident in pigs fed a basal diet. With older pigs fed 150 g oil per
kg meal there was little difference in rate of growth when pigs were fed at

a restricted level, but when fed to appetite those fed soybean oil ate more
and gained faster than those fed rapeseed oil. Water consumption was
greater for the pigs fed rapeseed oil. Carcass measurements did nut differ
significantly between treatments.

General Recommendations

As discussed in Chapters 1 to 4 and briefly outlined in the Introduction
to this chapter, the solvent-extracted rapeseed meal at present available in
Canada is a superior meal to that previously available in
Canada and elsewhere. Although swine are probably the least tolerant to
rapeseed meal of any of the domestic species (1, 16) this meal may be used
in the formulation of rations for most classes of pigs.

For young pigs during the starting period to 25 kg in weight, 4%
of the total ration may be composed of solvent-extracted rapeseed meal.
As the meal may lack in palatability, it is advisable to use it cautiously
in creep-feed rations. For market pigs from 25 to 90 kg liveweight, the meal
may be used as up to 10% of the total ration. Feed intake and rate of gain
may be reduced slightly at this level of feeding but efficiency of feed utiliz-
ation is not affected. The limited evidence available on the use of rapeseed
meal for pre-gestation, gestation and lactation suggests that as a protein
source, for swine breeding stock, particularly females during gestation and
lactation, rapeseed meal is unsuitable at a level above 3% of the total
ration. Breeding boars appear to be unaffected by a level of rapeseed meal
as high as that recommended for market pigs.

References

1. Altschul, A. M. 1958. Processed Plant Protein Foodstuffs. Academic Press Inc.,

New York, p. 577.

2. Anderson, H. H., and G. K. Hurwitz. 1953. Naunym-Schmiedebergs. Arch. Exp.

Pathol. Pharm. 219:119.

3. Bamji, M. S., and P. R, Sunderesan. 1961. J. Nutrition 74:39.

4. Bell, J. M. 1955. Can. J. Agr. Sci. 35:242.

5. Bell, J. M. 1958. Personal communication.

6. Bell. J. M. 1965. J. Animal Sci. 24: In Press.

7. Bell, J. M.. R. K. Downey and L. R. Wetter. 1963. Can. Dep. Agr. Pub. 1183.

8. Bo\vlan<l. J. P. 1957. Univ. Alberta Press Bull. 42(2) :5.

9. Bowland, J. P. 1958. Univ. Alberta Press Bull. 43(2) :11.

10. Bowland, J. P. 1963. Univ. Alberta Press Bull., 42nd Ann. Feeders' Day, p. 9.

11. Bowland, J. P. 1964. Unpublished data.

12. Bowland, J. P., and J. G. Manns. 1962. Univ. Alberta Press Bull., 41st Ann. Feeders'

Day, p. 13.

13. Bowland, J. P., S. Zivkovic and J. G. Manns. 1963. Can. J. Animal Sci. 43:279.

14. Cl.indmin, D. R., Ruth Renner and A. R. Robblec. 1959. Poultry Sci. 38:1367.

15. Cook, L. J. 1941. J. Dep. Agr. S. Australia. 45:176. (Nutrition Abstr. & Rev.

16:2361 1946.)

16. Fevrier, R. 1957. La Revue Frangaise des Corps Gras, 60 rue de Richelieu, Paris

2e, No. 3, p. 1.

17. Franke, E. R. 1958. Deutseh. Akad. Landwirtschaftswissensch., Berlin, Wissensch,

Abhandl. No. 37. p. 101.

18. Frolich, A., and F. Haring. 1937. Ztschr. Schweinezucht 44:533. (Nutrition Abstr.

& Rev. 7:4206, 1938.)

19. Frolich, A., and F. Haring. 1937. Ztschr. Schweinezucht 44:521. (Nutrition Abstr. &

Rev. 7:4212, 1938.)

20. Hussar, N., and J. P. Bowland. 1959. Can. J. Animal Sci. 39:84.

21. Hussar, N., and J. P. Bowland. 1959. Can. J. Animal Sci. 39:94.

22. Kennedy, T. H., and H. D. Purves. 1941. Brit. J. Exp. Pathol. 22:241.

23. Manns, J. G., and J. P. Bowland. 1963. Can. J. Animal Sci. 43:252.

24. Manns, J. G., and J. P. Bowland 1963. Can. J. Animal Sci. 43:264.

25. Manns, J. G., J. P. Bowland, V. E. Mendel and S. Zivkovic. 1963. Can. J. Animal

Sci. 43:271.

26. Morrison, F. B. 1959. Feeds and Feeding. The Morrison Publishing Co., Clinton,

Iowa.

27. National Academy of Sciences, National Research Council. 1964. Pub. 1192. Wash-

ington, D.C.

28. Norfeldt, S., N. Gellerstedt and S. Falkmer. 1954. Acta Pathol. Microbiol. Scand.

35:217.

29. Paloheimo, L., and B. Jakkola. 1959. Maataloust. Aikakausk 31 :212. (Nutrition

Abstr. & Rev. 30:2932, 1960.)

30. Paloheimo, L., P. Roine and E. Uksila (with R. Sirenius, H. Sauri and H. Unkila).

1959. Maataloust. Aikakausk 31:251. (Nutrition Abstr. & Rev. 30:5001, 1960.)

31. Roine, P., E. Uksila, H. Teir and J. Rapola. 1960. Ztschr. Ernahrungswiss. 1:118.

(Nutrition Abstr. & Rev. 31:924, 1961.)

32. Seale, M. E. 1952. Proc. Can. Soc. Animal Prod., p. 90.

33. Seale, M. E. 1953. Univ. Manitoba Livestock Day Rep.

34. Strothers, S. C. 1964. Personal communication.

CHAPTER 7. FEEDING VALUE OF RAPESEED MEAL

FOR POULTRY

D. R. Clandinin, Professor of Poultry Nutrition
University of Alberta, Edmonton

Introduction

Of interest in relation to recent research work on rapeseed meal are
the extensive studies by Frolich (15, 16, 17) in Sweden on solvent-processed
rapeseed meal, who reported that up to 10% rapeseed meal may be used
in the diet of growing chickens with only moderate growth retarding effect.
Thyroid enlargement, however, was noted even when as little as 5% rape-
seed meal was included in the chicks' diet. Frolich was able to reduce the
thyroid enlarging effects of rapeseed meal by extracting the meals with
water or 70% alcohol. He was also able to counteract the thyroid enlarge-
ment by administration of DL-thyroxine but was unable to alleviate the
condition by the inclusion of 10 ppm of supplementary iodine in the diet.

Starting and Growing Chickens

Much of the rapeseed meal produced in America prior to 1958 was
inferior to soybean meal as a protein feedstuff for chicks. In this regard, up
to 25% slower growth and 10% lower feed efficiency were frequently
obtained (11. 14. 23, 24, 29, 34, 36) from chick starter rations containing
rapeseed meal as compared to rations containing other protein feedstuff's
as the source of supplementary protein. Even when only part of the supple-
mentary protein in the ration was supplied by these expeller-processed
rapeseed meals, decreased growth rate and depressed feed efficiency oc-
curred (8, 11) (see Table 7.1).

It was soon learned (11) (see Table 7.2) that the use of high tem-
peratures during the cooking and conditioning of rapeseed in the expeller
process resulted in meals of inferior feeding value; the low feeding value
of over-heated meals was associated with a greater than 25% reduction
in the lysine content of the protein of such meals as compared to meals
subjected to less drastic heat treatment. On the other hand, low processing
temperatures were shown to leave more oil in the meals, an undesirable
effect from the processor's point of view, since he is primarily interested in
maximum oil yield. In further studies it was found (12) that in the expeller
process only sufficient heat should be applied in cooking and conditioning

97386—6

Table 7.1 Effect of expeller-processed rapeseed meal
on chick growth and feed efficiency

Ration number

Starter basal,* %

Ground wheat, %

Soybean meal

(44% protein), %

Argentine rapeseed
meal,f %

Polish rapeseed meal, J %

Protein (N X 6.25) in
ration, %

Number of chicks §

86 86 86 86 86 86 86 86

4.0 4.0 4.0 4.0 4.0 3.1 2.2 0.4

10.0 7.5 5.0 10.0 8.4 6.8 3.6

2.5 5.0 10.0

21.5 21.5 21.1 21.2 21.6 21.4 21.6 21.7

61 62 62 62 62 61 61 62

Average weight,

8 weeks, g 1,034 1,009 993 910 1,024 1,042 1,051 979

Feed/g gain, 8 weeks, g 2.6 2.7 2.8 2.9 2.6 2.6 2.6 2.7

*The starter basal contained the following ingredients: ground wheat, 42.125; ground corn, 20.0; ground oats,
5.0; dehydrated alfalfa meal, 3.0; meat meal, 4.0; herring meal, 3.0; soybean meal, 5.0; limestone, 1.5; bone meal,
1.0; iodized salt, 0.25; fish oil (2250A, 300D), 0.125 ; insoluble grit, 1.0. In addition, the starter basal was supplemented
with 0.23 kg manganese sulphate, 3 g riboflavin, 9 g calcium pantothenate, 15 g niacin, 0.45 kg dry Ds (1,650,000
ICU/kg), 0.91 kg Merck vitamin Bi2 and antibiotic feed supplement, 1.82 kg Merck 25% choline chloride premix
per ton of finished starter.

fMeal produced by the expeller process from Brassica napus rapeseed, N X 6.25 = 43.3.

JMeal produced by the expeller process from Brassica campestris rapeseed, N X 6.25 = 33.9.

§Single Comb White Leghorn, mixed sexes.

to permit reduction of the oil content of the meal to about 6% if damage
to protein quality as measured by lysine content was to be avoided. That
the lysine content of expeller-processed rapeseed meal can be limiting in
so far as its use in chick starter rations is concerned has been demonstrated
by Kratzer et al. (24) and Klain et al. (23) and confirmed in our labora-
tories (unpublished data). In these 1955 chick growth trials, the chicks
receiving rations supplemented with rapeseed meal weighed 222 g while
those receiving rapeseed meal plus 0.5% L-lysine weighed 352 g at 4 weeks
of age. (See Chapters 2 and 3 for further discussion of processing and meal
composition.)

Processors in Canada have converted from expeller processing to pre-
press-solvent or solvent methods of processing. This change has occurred
because processors realize that maximum oil yield may be obtained by
solvent methods without risk of heat damage to the protein of the by-
product. However, evidence has been obtained in our laboratory (8) that,

Table 7. 2. Effect of processing temperatures on the nutritive value and
chemical composition of expeller-processed rapeseed meal

Body,

Thyroid

Lysine in

Ratios

No. of weight

size, mg Protein

Fat in

protein

No.

Treatment*

chieks 4 wk

per 100 g in meal

meal

of meal

body wtf %

1 Soybean meal

Solvent processed 30 381.5 9.0 44.2 0.4 6.11

2 Rapeseed meal

Cooker* 121 C (250 F) 30 274.5 25.1 36.4 5.9 4.12

Conditioner | 127 C (260 F)

3 Rapeseed meal

Cooker} 11 2C (234 F) 30 324.0 19.5 35.0 6.6 4.86

Conditioner t 127 C (260 F)

4 Rapeseed meal

Cooker J 1 04 C (220 F) 30 365.0 20.0 34.8 7.3 5.69

Conditioner J 116 C (240 F)

Average run of rapeseed 31.8 35 . 0 6 . 42

*Meals incorporated as sole source of supplementary protein in a 22% protein chick starter.
tAverage of six male and six female chicks.

JCrushed seed took approximately 30 minutes to pass through the cooker and 5 minutes to pass through the
conditioner.

from the point of view of chick growth promotion alone, low-temperature
expeller-processed rapeseed meal can give just as satisfactory results as
prepress-solvent meal and both of these types of meals may be expected
to approach solvent-processed soybean meal in growth promotion (see Table
7.3). In spite of this fact, the switch to prepress solvent or solvent process-
ing of rapeseed in Canada has been complete. During 1958 to 1961 ten
prepress-solvent and five solvent-processed meals were tested in our labor-
atory in a chick starter at the 15% level, replacing an equivalent amount
of protein from soybean meal, no attempt being made to compensate for
the lower energy content of the rapeseed-containing rations. On the average,
the chicks fed prepress-solvent and solvent meals grew 94 and 95.4%
respectively as fast as chicks fed the soybean meal control ration.

In more recent studies in our laboratory, 14 samples of commercial
prepress-solvent and solvent-processed rapeseed meals were included in a
23% protein broiler ration at the 15% level as a replacement for part of
the soybean meal in the ration. The rations were kept isonitrogenous and
isocaloric. Energy levels were maintained constant by including supple-
mentary fat in the diets containing rapeseed meal. The fiber content of
the soybean control diet was 3.8% while that of the rapeseed meal rations
ranged from 5 to 5.5 percent. Growth of chicks and feed conversion were
equally as good on the rations containing rapeseed meal as on those contain-

97386—6i

Table 7.3 Composition of and chick growth obtained from
rapeseed meals compared to soybean meal

Meal
No.

Description

Year

meal

obtained

Protein Lysine in
in meal protein
% of meal
%

Average weight (g) of
chicks at 4 weeks of age*

Exp. Exp. Exp. Exp. Exp.
12 3 4 5

Solvent-processed
soybean meal

50.1ft

6.11

367 308 337 308 448

High-temperature
expeller rapeseed
mealf (RSM)

1957

36.4

4.12

226

Medium-temperature
expeller RSMf

1957

35.0

4.86

282

Low-temperature
expeller RSMf

1957

34.8

5.69

375

Prepress-solvent RSM

1958

37.8

5.10

339 280

Prepress-expeller RSM|

1958

36.4

5.53

363 297

Prepress-solvent RSMf

1958

38.5

5.50

347 300

Prepress-solvent RSM§

1959

37.6

5.27

323

Prepress-solvent RSM**

1959

40.2

4.84

317 307

Prepress-solvent RSM

1961

36.2

5.21

427

*In the soybean controls, 50% protein solvent soybean meal was the only source of supplementary protein. In
the rapeseed meal rations, all of the soybean meal was replaced on a protein equivalent basis with rapeseed meal,
the percentage of wheat being reduced in these rations to take care of the higher percentage of rapeseed meal re-
quired to replace the soybean meal. The following numbers of chicks were involved per treatment in the various
experiments: Experiment 1, 16 male chicks; Experiment 2, 20 male and 20 female chicks; Experiment 3, quadruplicate
lots of 20 chicks of mixed sexes; Experiment 4, duplicate lots of 25 male chicks; Experiment 5, quadruplicate lots of
12 chicks of mixed sexes.

t Prepared from similar raw material.

{Prepared from similar raw material.

§Prepared from Polish-type (Brassica napus) rapeseed.
**Prepared from Argentine-type (Brassica campestris) rapeseed.
tfThis soybean meal was used in Experiment 1 and Experiment 2.

ing soybean meal {see Table 7.4). These results stress the need for adjusting
the energy levels of rations containing rapeseed in order to compensate for
the lower metabolizable energy content of rapeseed meal as compared to
soybean meal (32, 33). Thyroid-to-body-weight ratios were higher in the
chicks fed rapeseed meal. The significance of the latter will be discussed in
this chapter.

The fact that "top quality" expeller-processed and prepress-solvent and
solvent-processed rapeseed meal approach or equal soybean meal in growth
promotion is not surprising since the essential amino acid content of the
protein of rapeseed and of good-quality rapeseed meal compares favorably
with that of the protein of soybean and of soybean meal respectively

Table 7.4. Relative feeding value of prepress-solvent and solvent
rapeseed meals as compared to soybean meal

Feed Thyroid

Ration Rapeseed meal Treatment Protein Relative per g size, mg

No. in meal growth f gainf per 100 g

No. Source* % % g body wtj

Experiment 1, 1962 Crop Rapeseed

Soybean meal

control

45.2

100.0

2.20

10.4

WCSP

15% RSM

36.7

106.4

2.15

15.8

WCSP

15% RSM

36.5

104.9

2.17

10.9

WCSP

15% RSM

36.5

106.2

2.19

15.9

WCSP

15% RSM

37.2

109.5

2.22

11.4

SWP

15% RSM

37.5

103.4

2.22

13.8

Experiment 2, 1962 Crop Rapeseed

Soybean meal

control

45.6

100.0

2.30

10.2

WCSP

15% RSM

36.4

100.4

2.18

16.7

CVO

15% RSM

38.9

102.2

2.10

17.8

SWP

15% RSM

39.5

105.2

2.05

17.8

SWP

15% RSM

40.0

105.6

2.06

17.1

Experiment 8, 1963 Crop Rapeseed

Soybean meal
control

44.8

100.0

2.46

6.4

SWP

15% RSM

39.8

98.7

2.58

10.9

SWP

15% RSM

38.7

99.2

2.50

12.2

SWP

15% RSM

39.2

96.4

2.60

11.6

WCSP

15% RSM

37.1

99.2

2.47

12.7

AVOP

15% RSM

38.3

97.7

2.55

16.0

Averages-

-Soybean

meal

45.2

100.0

2.32

9.1

Rapeseed meal

38.2

102.5

2.28

14.3

*AVOP, Agra Vegetable Oils Products Ltd., Nipawin, Saskatchewan.
CVO, Co-op Vegetable Oils Ltd., Altona, Manitoba.
SWP, Saskatchewan Wheat Pool, Saskatoon, Saskatchewan.
WCSP, Western Canada Seed Processors Ltd., Lethbridge, Alberta.

fDuplicate lots of 20 female chicks on each treatment in Experiment 1; 16 female chicks per treatment in Ex-
periment 2; and duplicate lots of 18 mixed chicks per treatment in Experiment '5.

{Average of six female chicks in Experiments 1 and 2; average of four male and four female chicks in Ex-
periment 3.

(10, 25, 26) (see Table 7.5). From the point of view of the two most limit-
ing amino acids in chick starters based on vegetable protein supplements,
i.e. lysine and methionine, rations supplemented with rapeseed meal are
likely to be similar or higher in methionine and somewhat lower in lysine
content than those supplemented with soybean meal. This may also be
deduced from the analytical data of Klain et al. (23) and De Vuvst et al.
(13).

Table 7.5. Percentages of some amino acids in the protein of rapeseed,

rapeseed meal, soybeans and soybean meal as determined by

microbiological assay

Rape Soybean

Amino acid

Seed*

Mealf

Seedt

Meal§

Arginine

5.8

7.7

7.5

Histidine

2.2

2.9

2.3

2.5

Isoleucine

3.9

4.1

5.3

5.5

Leucine

6.4

7.2

7.9

7.7

Lysine

5.4

5.5

6.6

6.2

Methionine

1.3

1.3**

1.4

Phenylalanine

3.6

4.1

5.1

4.9

Threonine

4.0

4.4

3.9

4.0

Valine

4.3

5.4

5.3

5.4

*Average of four varieties grown at three different locations in Alberta in 1955 (10).

fAverage of 15 samples of prepress-solvent and solvent-processed rapeseed meal processed during 1958-61 (D.R.
Clandinin, unpublished data).

{Average of 20 strains of soybeans (25).

§Lyman et al. (26).
**When these 15 samples of rapeseed meal were analyzed for amino acid content using a Beckman/Spinco amino
acid analyzer, an average value for methionine of 1.9% of the protein was obtained (D.R. Clandinin, unpublished
data, 1962-63).

Laying and Breeding Chickens

O'Neil (28) reported on three experiments designed to assess the suit-
ability of expeller-processed rapeseed meal as a replacement for soybean
meal in laying rations for chickens. In one experiment, varying amounts
of rapeseed meal replaced soybean meal on a protein equivalent basis in
the diet. In addition to the vegetable protein supplement, the rations con-
tained 2% meat meal and 1% fishmeal as sources of supplementary protein.
No significant differences between treatments for either percentage produc-
tion or amount of feed required to produce a dozen eggs were observed.
In a second experiment, in addition to replacing soybean meal on a protein
equivalent basis, the levels of calcium and phosphorus were adjusted so
that the diets had the same quantity of these minerals. Again egg production

and feed per dozen eggs were found to be similar for both treatments. In
tlic third experiment rapeseed meal was used to replace all of the soybean
meal when animal protein was fed at either the 3 or 1^% level. No significant
differences between treatments in the productive traits studied or in hatch-
ability of eggs produced were noted. In our laboratory (unpublished data,
1955-561 groups of 30 White Leghorn pullets in batteries laid at similar
rates over a 24-week period when fed rations containing 0, 3, 6 and 9%
expeller-processed rapeseed meal replacing soybean meal. In addition to the
vegetable protein supplement (s) the rations contained 0.5% fishmeal.

Starting and Growing Turkeys

Blakely and Anderson (3, 4) demonstrated that the inclusion of rape-
seed meal, presumably expeller-processed meal, in a turkey starting ration
as a replacement for meat meal reduced growth rate. However, the fact
that these workers observed white barring in the groups fed rapeseed meal
suggests that the meal used was low in lysine content, which may account
for the reduced growth noted. In a later experiment MacGregor and Blakely
(27) again found that the inclusion of 10% of expeller-processed rapeseed
meal as a replacement for soybean meal in rations fed turkeys from day-
old to 24 weeks depressed rate of growth significantly. It would appear that
more research should be undertaken to determine the effects of feeding high-
quality solvent-processed rapeseed meal to starting and growing turkeys.

The use of whole rapeseed as an energy source in finishing rations for
turkeys has been studied by Blakely and MacGregor (5). The control diet
contained 10% of stabilized tallow while the diet containing whole rapeseed
contained sufficient whole rapeseed to supply 10% oil. The protein content
of the latter diet was adjusted by removing part of the soybean meal and
ground wheat. At the end of a 4- week feeding period no differences were
noted in the body weight of the birds on the two treatments, however, a
highly significant improvement in carcass score was noted in the turkeys
fed whole rapeseed.

Laying and Breeding Turkeys

In studies on the use of expeller and prepress-solvent-processed rape-
seed meal in turkey breeding rations as a replacement for soybean meal,
MacGregor and Blakely (27) found that 10% expeller or prepress-solvent-
processed meal could be used without adverse effects on egg production or
feed efficiency. In so far as hatchability was concerned, there were indications
that expeller-processed rapeseed meal did not support quite as high hatch-
ability as soybean meal (see Table 7.6). These workers suggested that the
expeller-processed meal may have been slightly low in lysine content and
that this may have accounted for the difference in the results obtained from
the two types of meals. In a two-year study in which, in each year, duplicate

Table 7.6. Effect of prepress-solvent rapeseed meal as a
replacement for soybean meal in a turkey breeding ration*

Soybean meal
control

10% prepress-
solvent-processed
rapeseed meal

Birds per ration

Broodiness, cases

173

180

Production, hen-da}r.

, %

48.0

45.0

Average egg weight,

91.1

90.4

Change in body weig

ht, kg

+ .19

+ .13

Feed per dozen eggs,

6.3

6.4

Hatch of fertile eggs.

, %

65.0

63.0

*Data from MacGregor and Blakely (27). None of the differences between treatments
were significant (P <0.10).

groups of 72 Broad Breasted turkeys were fed a breeding ration containing
soybean meal as the main supplementary source of protein and one in which
solvent-processed rapeseed meal replaced most of the soybean meal in the
ration, Robblee and Clandinin (unpublished data, 1962-63) noted no adverse
effects on egg production, feed conversion or percentage hatch as a result
of the substitution (see Table 7.7 for 1963 data).

Table 7.7. Effect of solvent-processed rapeseed meal as a
replacement for soybean meal in a turkey breeding ration*

Soybean meal
control

10% solvent
rapeseed meal

Birds per ration

144

Mortality, no.

Broodiness, no.

226

204

Production, hen-housed, %

55.5

Feed per dozen eggs, kg

6.8

7.2

Fertility, %

82.7

79.4

Hatch of fertile eggs, %

66.6

72.0

Hatch of all eggs, %

55.0

57.1

*Experiment covered period January 1 to April 30, 1963 (unpublished data of A.R.
Robblee and D.R. Clandinin).

Goitrogenic Effects of Rapeseed Meal in Poultry

Workers in New Zealand (18, 19, 20, 21, 22, 30) have studied exten-
sively the effects on the thyroid and pituitary glands of feeding rapeseed to
rats. Details of their work are reviewed in Chapter 4 of this publication;
however, reference here to their work does not seem out of place since
it ties in closely with work that has been done with poultry. Briefly, these
workers found that the feeding of rapeseed to rats interferes with the power
of the thyroid to synthesize thyroxine. The resultant fall in the level of
thyroxine in the circulation induces the pituitary to secrete excessive
amounts of thyrotropin which acts on the thyroid causing hypertrophy and
hyperplasia. By the end of the third week on rations containing rapeseed,
thyroid changes are at a maximum. After this, growth of the gland parallels
that of the rat. The thyroid apparently reaches physiological equilibrium
at an increased thyroid-to-body-weight ratio.

Numerous workers (3, 11, 14, 17, 23, 34, 36) have reported thyroid
enlargement as a result of feeding rapeseed meal to poultry. In general,
meal produced from Argentine-type seed {Brassica napus) has been shown
(11, 23) to cause a greater degree of enlargement than meal produced from
Polish-type seed {Brassica campestris). This is attributed to the higher
(-)-5-vinyl-2-oxazolidinethione content of rapeseed meal produced from
B. napus seed as compared to that produced from B. campestris seed
( 10, 35). (Astwoocl et al. (1, 2) and Carroll (6) isolated goitrin from rape-
seed and identified it as L-5-vinyl-2-thiooxazolidone, which has more re-
cently been named (-)-5-vinyl-2-oxazolidinethione, see Chapter 4.) It has
also been observed that prepress-solvent and solvent-processed rapeseed
meals are slightly less goitrogenic to poultry than expeller-processed meals
((11) and Table 7.4). This difference is no doubt mainly due to the fact
that a higher percentage of the rapeseed grown throughout Canada in
recent years has been of the B. campestris type.

Efforts to counteract the thyroid enlargement of chickens fed rapeseed
meal by feeding supplementary iodine have been only partially successful
(9, 14, 23, 24). On the other hand, feeding Protamone or injecting L-thy-
roxine has resulted in a reduction of the thyroid-to-body-weight ratio of
rapeseed meal fed poultry (4, 9, 23, 24).

Clandinin and Bayly (9) studied the histology of the thyroid glands
of chickens and laying hens that had been fed rapeseed meal with and
without >tabilized iodine for a month or more. They found that an in-
crease in the number and size of the epithelial cells in the glands accounted
for the increase in thyroid size of growing chickens fed rapeseed meal.
When stabilized iodine was added to the diet of rapeseed meal fed chicks,
the glandular enlargement was found to be caused by increased follicle size
and increased colloid storage; however, the cells appeared normal in size

and shape. In the case of laying hens fed rapeseed meal, initially, the glands
exhibited enlargement as a result of an increase in number of follicles, the
follicles being well defined. As time of treatment progressed, the follicles
toward the central portion of the glands became distorted and completely
filled with cells and the amount of colloid was greatly reduced. When
stabilized iodine was added to the ration of rapeseed meal fed layers, the
glands were enlarged. The glandular enlargement in this instance was found
to be caused by increased follicle size and increased storage of colloid. As
in the case of chicks, iodine supplementation tended to bring about a more
normal stucture in the glands. It would appear from this work that rape-
seed meal in the diet of chickens results in histological changes in the thyroid
glands and that provision of adequate amounts of iodine in the diet tends
to correct the abnormal histological picture.

In an extensive series of experiments designed to study the effects
of rapeseed meal, progoitrin and goitrin on the uptake and release of radio-
iodine from the thyroid glands, Clandinin, Caballero and Bayly (un-
published data, 1961-64) found that the initial effect of including these
supplements in the diet of the chick is that of decreasing the uptake of
radio-iodine by the thyroid glands and increasing the rate of release of
radio-iodine from the glands. It is not known at this time whether the
iodine released from the glands is in free or bound form. It was also found
that after chicks have received any one of these supplements for several
weeks, the uptake of radio-iodine by the hypertrophied glands is greatly
increased. The daily secretion of radio-iodine from the latter glands, how-
ever, was found to be normal. These results support the conclusion that
chicks fed rapeseed meal, progoitrin or goitrin, like rats fed rapeseed (18,
19, 20, 21, 22, 30), eventually reach physiological equilibrium at increased
thyroid-to-body-weight ratios. Results of this study also showed that
goitrin ( (-)-5-vinyl-2-oxazolidinethione) at relatively high levels in the
diet depresses chick growth and that myrosinase from rapeseed does not
have to be supplied in the diet for progoitrin to produce its anti-thyroid
effects in the chick. Progoitrin is converted to goitrin by the enzyme my-
rosinase which is present in rapeseed. The latter observation is in agree-
ment with the finding in our laboratory that expeller-processed rapeseed
meals are goitrogenic yet they show no myrosinase activity.

Schwarze (31) has shown that the bitter taste of ground rapeseed is
due to sinapin. Clandinin (7) has demonstrated that when sinapin, isolated
from rapeseed meal as the thiocyanate and purified as the bisulfate, was
added to a soybean-meal-type chick starter at a level which would supply
an amount of sinapin comparable to that present in a starter ration in
which the main source of supplementary protein was rapeseed meal, normal
growth rate was obtained. Hence, the bitter substance in rapeseed meal
cannot be implicated in the chick growth depressions that have been
obtained from some commercial rapeseed meals.

Summary and General Recommendations

Many expeller-processed rapeseed meals have been found to support
a low rate of growth in chicks and poults. Low-temperature expeller-
processed rapeseed meals have been shown to approach or equal soybean
meal for chick growth promotion. In general, where slow growth rate has
been obtained from expeller-processed rapeseed meal, it has been associated
with low lysine content of the meals resulting from over-heating during
processing. Prepress-solvent and solvent-processed rapeseed meals, which,
of course, have not been subjected to excessive heat treatment in processing.
have, in contrast, been found equivalent to soybean meal for chick growth
promotion and feed conversion when energy-protein relationships are
maintained constant. This seems quite understandable since the amino acid
distribution in rapeseed protein has been shown to be comparable to that
of soybean protein. On the basis of the growth studies reviewed there does
not appear to be any reason why 10 to 15% low-temperature expeller, pre-
press-solvent or solvent-processed rapeseed meal should not be used in
chick starter rations.

In so far as laying and breeding chickens and turkeys are concerned,
10% prepress-solvent or solvent-processed rapeseed meal has been shown
to yield just as satisfactory production, feed conversion, fertility and hatch-
ability as corresponding amounts of protein from soybean meal.

Efforts to counteract thyroid enlargement caused by rapeseed meal
by feeding supplementary amounts of stabilized iodine, have only been
partially successful. Enlargement, however, has been suppressed by feeding
Protamone or by L-thyroxine injection.

It would appear that the initial effects on the thyroid glands caused
by feeding rapeseed meal to poultry include decreasing the uptake of iodine
by the glands and increasing the release of iodine from the glands. After
poultry have been fed rapeseed for 3 or 4 weeks, uptake of iodine by the
hypertrophied thyroid glands is greatly increased while secretion rate from
the glands appears normal. It would seem, therefore, that after poultry
have received rapeseed meal for a short period of time a physiological
equilibrium is reached at an increased thyroid-to-body-weight ratio.

References

1. Astwood, E. B., M. A. Greer and M. G. Ettlinger. 1949. Science 109:631.

2. Astwood, E. B., M. A. Greer and M. G. Ettlinger. 1949. J. Biol. Chem. 181:121.

3. Blakely, R. M., and R. W. Anderson. 1948. Sci. Agr. 28:393.

4. Blakely, R. M., and R. W. Anderson. 1948. Sci. Agr. 28:398.

5. Blakely, R. M., and H. I. MacGregor. 1960. Poultry Sci. 39:1235 (Abstr.).

6. Carroll, K. K. 1949. Proc. Soc. Exp. Biol. Med. 71:622.
7 Clandinin, D. R. 1961. Poultry Sci. 40:484.

8. Clandinin, D. R. 1962. Proc. Xllth World's Poultry Congr., p. 259.

9. Clandinin, D. R., and Louise Bayly. 1960. Poultry Sci. 39:1239. Abstr.

10. Clandinin, D. R., and Louise Bayly. 1963. Can. J. Animal Sci. 43:65.

11. Clandinin, D. R., Ruth Renner and A. R. Robblee. 1959. Poultry Sci. 38:1367.

12. Clandinin, D. R., and E. W. Tajcnar. 1961. Poultry Sci. 40:291.

13. De Vuyst, A., W. Vervack, M. Van Belle, R. Arnould and A. Moreels. 1963. Agri-

cultura (Louvain) 11:385.

14. Dow, D. S., and C. E. Allen. 1954. Can. J. Agr. Sci. 34:607.

15. Frolich, A. 1952. Statens Husdjursforoks sartryck och forhandsmeddelande 92.

16. Frolich, A. 1952. Kungl. Lantbrukshogskolans Ann. 19:205.

17. Frolich, A. 1953. Kungl. Lantbrukshogskolans Ann. 20:105.

18. Griesbach, W. E. 1941. Brit. J. Exp. Pathol. 22:345.

19. Griesbach, W. E., T. H. Kennedy and H. D. Purves. 1941. Brit. J. Exp. Pathol.

22:349.

20. Griesbach, W. E., and H. D. Purves. 1943. Brit. J. Exp. Pathol. 24:174.

21. Hercus, C. E., and H. D. Purves. 1936. J. Hyg. (Cambridge) 36:182.

22. Kennedy, T. H., and H. D. Purves. 1941. Brit. Exp. Pathol. 22:241.

23. Klain, G. J., D. C. Hill, H. D. Branion and J. A. Gray. 1956. Poultry Sci. 34:1315.

24. Kratzer, F. H., P. N. Davis, D. E. Williams and B. J. Marshall. 1954. J. Nutrition

53:407.

25. Kuiken, K. A., and C. M. Lyman. 1949. J. Biol. Chem. 177:29.

26. Lyman, C. M., K. A. Kuiken and F. Hale. 1956. J. Agr. Food Chem. 4:1008.

27. MacGregor, H. I., and R. M. Blakely. 1964. Poultry Sci. 43:189.

28. O'Neil, J. B. 1957. Poultry Sci. 36:1146 (Abstr.).

29. Pettit, J. H., S. J. Slinger, E. V. Evans and N. F. Marcellus. 1944. Sci. Agr. 24:201.

30. Purves, H. D. 1943. Brit. J. Exp. Pathol. 24:171.

31. Schwarze, P. 1949. Naturwissenschaften 36:88.

32. Sibbald, I. R., and S. J. Slinger. 1962. Poultry Sci. 41:1612.

33. Sibbald, I. R., and S. J. Slinger. 1963. Poultry Sci. 42:707.

34. Turner, C. W. 1946. Poultry Sci. 25:186.

35. Wetter, L. R., and B. M. Craig. 1959. Can. J. Plant Sci. 39:395.

36. Witz, W. M., M. M. Carpenter and J. W. Hayward. 1950. Poultry Sci. 29:786

(Abstr.).

CHAPTER 8. STATUS OF RAPESEED MEAL AS A PROTEIN

SUPPLEMENT

A. R. Robblce, Professor of Poultry Nutrition
University of Alberta, Edmonton

In the foregoing chapters an attempt has been made to provide an
up-to-date review of authentic information on rapeseed meal that may
be of interest and value to users and potential users of the product. It
has been the opinion of many research workers in Canada that the rapeseed
meals being produced today are much superior to those produced a few
years ago. It has also been their belief that the modern meals are not
being used in feed formulation to as great an extent as they might be when
factors such as quality, availability and price are taken into consideration.
It is hoped that this monograph, which includes results of recent research
on rapeseed meal, may serve to counteract prejudices against rapeseed meal
as a protein supplement arising from some adverse results obtained with
meals produced 10 or 15 years ago.

Rapeseed is a crop well adapted to Canadian conditions. It matures
in a relatively short growing season; it provides an alternative to cereal
crops in a cropping program; it is a good source of vegetable oil, and, as
a byproduct of oil extraction, it provides a high-protein meal suitable for
livestock feeding.

In Canada, acreage devoted to rapeseed production has increased
rapidly until supply of the seed has greatly exceeded domestic demand.
As a consequence, in recent years Canada has exported more rapeseed
than all other countries in the world combined. The product is usually
exported as the seed ; it is crushed and extracted by the importing country.

For the most part, two types of rapeseed are being produced in Canada,
B. napus (Argentine rape) and B. campestris (Polish rape). Of the two
species, B. napus has a greater potential yield of seed and oil than B.
campestris but varieties of the latter species are usually preferred in
Canada because they mature approximately 2 weeks earlier.

Breeding programs have been undertaken in Canada to produce new
varieties of rapeseed. Factors being considered in developing new varieties
include yield of seed and oil. composition of the oil and level of thioglucosides
in the Beed. Considerable progress has been made; varieties have been
selected with greater yield potential, differing oil composition, and lower
levels of the thioglucosides. The future holds promise that varieties will be
produced that arc vastly superior to those now available.

Processing methods used for the extraction of oil from rapeseed have
undergone considerable change over the years. Ten or 15 years ago most
of the meal was produced by the expeller process ; today, meals are produced
in Canada by either the prepress-solvent or by the solvent process. As a re-
sult the meals currently being produced differ from those that were available
previously. Modern meals are subjected to less heat during processing and
the amount of oil left in the meal is greatly reduced as compared to
expeller meals. Because of the reduction in the amount of heat used in
processing, the meals are of much better quality than those produced a
few years ago.

Modern varieties of rapeseed yield approximately 40% of oil and
50% of meal, with the remainder being moisture. Examination of the
analyses of the proximate principles of the meals indicates that, in general,
they are comparable to other plant protein meals. Protein levels vary
depending upon variety, year and soil type with values ranging from 32
to 44% ; fat content depends on the extraction procedures employed but
usually ranges from 1 to 2% in prepress-solvent or solvent meals; crude
fiber levels in the meals are higher than in most other plant protein meals;
and levels of nitrogen-free extract and ash are similar to those found in
other oil seed meals.

When one examines the essential amino acid composition of modern
rapeseed meals it is obvious that the protein that is present is suitable for
livestock feeding. The balance or array of amino acids is superior to that
seen in many other plant protein meals and compares quite favorably with
soybean meal. It would therefore appear that the potential of rapeseed meal
as a protein supplement has often been overlooked. Failure to recognize
this potential may have stemmed from earlier reports of experimental work
conducted with expeller meals in which damage to the protein had occurred
during processing. The use of high temperatures during processing results
in a reduction in the levels of some of the essential amino acids in the
meals produced. For instance, with meals produced by the expeller process,
values for the amount of lysine present generally ranged from 3.5 to 4.4%
of the protein as compared to an average of 5.5% of lysine found in the
protein of a number of solvent meals for which values have been reported.
Since lysine is often the most limiting of the essential amino acids in
practical feeds for monogastric animals, estimations of the value of the
protein in rapeseed meal should recognize the importance that lysine level
may have on the biological value of the protein. If lysine levels are used
as a basis of comparison the protein of solvent-processed rapeseed meals
would have approximately 90% as much value as the protein of soybean
meal.

In the preceding chapters several references have been made to the
presence of thioglucosides in rapeseed meal and to the possible adverse
effects that their hydrolytic products, isothiocyanates and oxazolidinethione,
may exert on thyroid size, reproduction, growth rate and livability in some

species of animals. There is no doubt that problems arising because of the
effects of these compounds on the animal have been responsible for much
of the bad publicity that rapeseed meal has received in the past. The
situation is complicated by many factors. Levels of isothiocyanates and
oxazolidinethione in rapeseed meal may vary depending upon variety,
growing conditions, levels of available sulfate in the soil, and processing
methods used in producing the meal. In addition effects noted in experi-
mental animals may be influenced by age, sex and species. Because of the
many variables that may be involved it is sometimes difficult or impossible
to ascribe the effects noted to a particular factor. In so far as the thiogluco-
side levels and their effects on livestock and poultry are concerned, one
might optimistically predict that the plant breeder will, in time, produce
varieties containing very low levels of these substances. In the meantime,
it is apparent that varieties of Polish rapeseed contain lower levels of
glucosides, are less goitrogenic and, therefore, are of superior quality to
varieties of Argentine rapeseed in livestock feeding.

In order to obtain the greatest measure of satisfaction from the use of
rapeseed meal, some attention should be given to the differences that do ex-
ist between species of animals in their response to the inclusion of rapeseed
meal in the ration. This varies from little or no effect with ruminants, slight
effects with growing swine and poultry, to serious impairment of reproduc-
tive ability with breeding swine. The occurrence of variability of this sort
serves to emphasize that research results obtained with one species may
not necessarily be applicable to another. It also indicates that rapeseed
meal should be used within the limits that have been shown to be suitable
by appropriate experimentation with the species involved.

The use of rapeseed meal in rations for cattle and sheep has resulted
in little real difficulty; nevertheless, the product has been regarded with
some disfavor by producers. Resistance against the use of the meal has
arisen because of an apparent reluctance on the part of ruminant animals
to consume rations containing rapeseed meal when such feeds are first fed.
The lack of acceptability only lasts for the first few days of the feeding
period, after which palatability no longer appears to be a problem. Because
lack of palatability may be a problem initially, if rapeseed meal is to be
incorporated into a ration at high levels, it is generally recommended that
the meal be introduced gradually into the feeding program.

The results of numerous experiments with cattle and sheep indicate
that no serious problems should be encountered through the use of rape-
seed meal in practical rations. Ruminant animals do not develop enlarged
thyroid glands and no adverse effects on the rate of gain or reproduction
have been noted when solvent-extracted rapeseed meal was fed at high
levels. In addition, neither yield nor flavor of the milk was affected by
inclusion of rapeseed meal in the ration. These results have led to a general
recommendation that solvent-extracted rapeseed meals, similar to those

produced in Canada, can be considered to be equivalent to other plant
protein meals when used in rations for ruminants at levels up to 10% of
the total dry matter of the ration.

Rapeseed meal is also a satisfactory protein supplement for swine,
but it should be used with more caution in rations for this species than
for ruminants. There is some evidence that swine are less tolerant than
other farm livestock to rations containing high levels of rapeseed meal.
When high levels of the meal are fed the thyroid gland may be enlarged,
rate of growth may be reduced, and adverse effects on reproduction and
lactation may be noted. For these reasons, levels of rapeseed meal fed
should not exceed the maximum levels that are recommended. It is generally
recommended that for growing pigs to 25 kg in weight, 4% of the ration
may be composed of rapeseed meal while for growing pigs from 25 to
90 kg in weight, up to 10% of rapeseed meal may be used in the ration.
For breeding stock during gestation and lactation it is suggested that the
level of rapeseed meal used should be restricted to a maximum of 3% of
the ration.

The use of rapeseed meal in rations for poultry has increased greatly
in recent years. Although the feeding of high levels of the meal causes some
enlargement of the thyroid glands of poultry with the degree of enlarge-
ment increasing as the level of rapeseed meal in the ration is increased, it
does not appear that poultry are too sensitive to the goitrogenic agents
of rapeseed. Rate of growth, egg production, fertility, hatchability and
livability of chickens and turkeys are apparently not affected by the changes
that occur in the thyroid glands. As a consequence the need for caution in
the use of the meal is less than is the case with swine.

On the basis of extensive experiments with poultry, it is generally
recommended that levels as high as 10 to 15% of rapeseed meal may be
included in starting and growing rations and as much as 10% may be used
in rations for laying and breeding chickens and turkeys. When prepress-
solvent, solvent or expeller meals processed at low temperatures are used
at recommended levels the protein has been found to be approximately
equivalent to that of soybean meal when energy-protein relationships are
kept constant. It should be emphasized, however, that care must be taken
that the level of lysine in the ration does not become a limiting factor
because the protein of rapeseed meal only contains approximately 90% as
much lysine as does the protein of soybean meal.

The future of rapeseed meal as a protein supplement for various
classes of farm livestock appears bright. Progress that has been made in
improving the quality of rapeseed meal and increasing our understanding
of some of the basic factors affecting quality would warrant a prediction
that rapeseed meals of the future will be much superior to those now being
produced. The improvement in quality should lead to increased usage of
rapeseed meal in the years to come.

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