PUBLICATION NO. 769
TECHNICAL BULLETIN NO. 54
DOMINION OF CANADA, DEPARTMENT OF AGRICULTURE
ISSUED JUNE, 1945
FIRST PRINTING
Canada
Canadian Agriculture Library
Bibliotheque canadienne de I'agriculture
Ottawa K1 A 0C5
The Chemical Composition of Native Forage
Plants of Southern Alberta and
Saskatchewan in Relation
to Grazing Practices
by
S. E. CLARKE and E. W. TISDALE
Experimental Farms Service
30.4
1212
'769
945
2
Published by Authority of Hon. the JAMES G. GARDINER, Minister of Agriculture,
Ottawa, Canada
3:45
PUBLICATION NO. 769 ISSUED JUNE, 1945
TECHNICAL BULLETIN NO. 54 FIRST PRINTING
DOMINION OF CANADA, DEPARTMENT OF AGRICULTURE
The Chemical Composition of Native Forage
Plants of Southern Alberta and
Saskatchewan in Relation
to Grazing Practices
by
S. E. CLARKE1
Agricultural Scientist
In charge of Forage Crops and Pasture Studies
Dominion Experimental Station,
Swift Current, Sask.
E. W. TISDALE2
Agrostologist
Dominion Experimental Station,
Swift Current, Sask.
1, 2— Formerly at the Dominion Range Experiment Station,
Manyberries, Alberta
Published by Authority of the Hon. JAMES G. GARDINER. Minister of Agriculture,
Ottawa. Canada.
28428—2
Digitized by the Internet Archive
in 2012 with funding from
Agriculture and Agri-Food Canada - Agriculture et Agroalimentaire Canada
http://www.archive.org/details/chemicalcompositOOclar
TABLE OF CONTENTS
Page
Introduction 7
Description of the Area 8
Location and Extent 8
Topography 8
Climate 8
Soils 10
Native Vegetation 12
Shortgrass Prairie 12
Mixed Prairie 13
Submontane Prairie 13
Sandhill Vegetation 14
Forest Vegetation 15
Methods of Study 16
Review of Literature 16
Chemical Composition of Principal Forage Species 18
Shortgrass Prairie Species 18
Principal Grasses and Sedges 19
Grasses of Secondary Importance 21
Broad-leaved Species 22
Mixed Prairie Species 24
Submontane Prairie Species 25
Sandhill Species 26
Forest Species 28
Meadow Species 29
Cultivated Species 31
Discussion of Results 33
Variability of the Data 33
Correlation Among Chemical Constituents 34
Differences Among Species and Growth Stages 35
Changes in Chemical Composition with Growth Development . 37
The Leaf -stem Ratio in Relation to Chemical Composition 40
Effects of Certain Factors on Chemical Composition of Native Forages 41
Effects of Climate 41
Effects of Soil 43
Effects of Commercial Fertilizers 44
Chemical Composition in Relation to Livestock Nutrition and Grazing Practices 45
Chemical Composition and Nutritive Value 45
Palatability of Forage in Relation to Livestock Nutrition 47
Seasonal Changes in Chemical Composition in Relation to Gains Made by Livestock 49
The Chemical Composition of Forages in Relation to Grazing Practices 50
Mineral Deficiencies and Supplements 51
Summary and Conclusions 55
Acknowledgments , 57
References 57
Appendix — List of Plant Species 59
The Chemical Composition of Native Forage Plants of
Southern Alberta and Saskatchewan in Relation to
Grazing Practices
BY
S. E. Clarke and E. W. Tisdale
INTRODUCTION
The livestock industry constitutes a branch of agriculture of steadily
increasing importance in Western Canada. In 1944, the livestock population of
the three Prairie Provinces of Manitoba, Saskatchewan and Alberta included
1,712,800 horses, 4,621.000 cattle and 1,873,150 sheep. While the number of
horses has decreased slightly, the numbers of cattle and sheep show a sub-
stantial increase over those of previous years. The bulk of the forage eaten by
these animals is obtained from the native pasture lands of the area, which
have been estimated to occupy at least forty million acres. The importance of
securing proper utilization of these grazing lands and of providing adequate
nutrition for the livestock population has become more fully realized in recent
years.
Scientific studies of native pasture lands in Western Canada are of fairly
recent origin. In 1927 the Dominion Range Experiment Station, the first institu-
tion of its kind in Canada, was established near Manyberries, in southeastern
Alberta. At this station studies of shortgrass prairie vegetation and of the
management of range livestock have been conducted. More recently, a program
of pasture surveys and research covering a greater variety of range types has
been initiated at the Dominion Experimental Station at Swift Current, Saskat-
chewan. The results of many of these studies have been presented in two
recent publications (7, 8) .
In addition to the projects reported in these publications, an investigation of
the chemical composition of the native vegetation was started early in the course
of the range studies at the Manyberries Station. It was realized that the chemical
composition of the native herbage may have an important bearing on such
matters as the value of various pasture types during different seasons of the
year, the gains in weight made by livestock during different parts of the
growing season, and the most profitable time to market range livestock. The
extent to which supplementary feeding is needed and the time of the year when
it is necessary may be revealed also by analyses of the pasture vegetation.
Studies in other pasture areas of the world had shown that great differences may
occur in the nutritive value of different plant species, of a single species in
different growth stages, or of any one species grown under different conditions
of soil or climate. Some of these researches had revealed the presence of marked
deficiencies in the composition of pasture forage which interfered seriously with
the nutrition of livestock. It was evident that the nutritive value of the native
pasture species as well as their palatability, productivity and reaction to grazing
would have to be determined before range management plans aimed at maximum
production of livestock could be developed.
Chemical analysis, while not capable of giving as full information regarding
nutritive value as would actual digestibility trials, was adopted as the only
practicable means of securing an estimate of the feeding value of the large
number of native forage species occurring in the area. Deficiencies of essential
7
28428—3
8
elements and the relative composition of different forages can be revealed by
chemical analysis. Where the chemical composition of a species is known,
an estimate of its actual nutritive value often may be obtained from the results
of feeding trials which have been conducted with forages of similar composition.
During the period 1927 to 1940, approximately one thousand samples of
native vegetation were collected and analysed. These included all the more
important species of the prairies as well as considerable material from other
range areas including the Great Sandhills, Cypress Hills and foothills of the
Rocky Mountains.
Only a few preliminary data have been published previously (5,6). The
results of the entire study of the chemical composition of native pasture species
in relation to grazing practices and livestock production in southern Sask-
atchewan and Alberta are presented in the present publication. Further studies
of the composition of prairie, sandhill and forest forages as well as more
intensive investigations of the effects of climate and soil on the chemical
constituents of pasture herbage are in progress.
DESCRIPTION OF THE AREA
Location and Extent
The area included in this study is indicated in Fig. 1. Roughly, it
comprises a tract extending from the southeastern corner of Saskatchewan on
the east to the foothills of the Rocky Mountains on the west. The boundary
between the United States and Canada constitutes the southern border of the
area, while its northern limits lie along a line passing close to the towns of
Qu'Appelle and Marsden in Saskatchewan and Vermilion and Stettler in
Alberta. This region is nearly the same as that occupied by the Brown and
Dark Brown soil zones in Saskatchewan and Alberta, with the addition of
certain areas in the Cypress Hills and Rocky Mountain Foothills. It is
estimated that there are close to thirty million acres of native pasture land in
this region.
Topography
The greater part of the area is occupied by a level to undulating plain,
which rises gradually from the east to its western limit at the foothills of the
Rockies. The continuity of the plain is broken by a number of hilly areas, of
which the Cypress Hills is the most prominent. In addition, there are areas of
rough topography in the Great Sand Hills and other localities where sand dune
formation has occurred. Broad valleys from 100 to 500 feet deep are typical
features. These include the valleys of the North and South Saskatchewan, and
of the Bow, Red Deer and Milk rivers. The average altitude of the plain varies
from 1,500 feet above sea level along the eastern edge of the area to 3,500 feet
and over at the western limits. The Cypress Hills reach an altitude of nearly
5,000 feet at their highest point, but none of the other ranges is so prominent.
Climate
Moisture is the limiting factor for plant, growth over most of the area.
Precipitation is low in amount and irregular in distribution, particularly in the
southwest and south central portions of the region. Other features of the climate
include a high rate of evaporation, great extremes of temperature, high and
frequent winds and abundant sunshine. In the Rocky Mountain Foothills and
the Cypress Hills these conditions are modified considerably due to greater
altitude. Moisture conditions are more favourable, but the frost-free season
is shorter in these regions.
9
28428—34
10
Meteorological data for typical stations in the area are presented in
Table 1.
TABLE 1.— CLIMATIC DATA FOR TYPICAL STATIONS IN SOUTHERN SASKATCHEWAN
AND ALBERTA
Station
Pincher Creek, Alta —
Lethbridge, Alta1
Medicine Hat, Alta
Manyberries, Alta1
Swift Current, Sask.1. . .
Regina, Sask
Scott, Sask.1
Klintonel, Sask
(Cypress Hills region)
Soil Zone
Shallow Black
Dark Brown. .
Brown
Brown
Brown
Dark Brown. .
Dark Brown..
Dark Brown. .
Mean
Average
Annual
Precipitation
Temp.
in inches
in Degrees
Fahrenheit
Annual
April-July
Inch
390
19-93
9-74
41-2
15-76
7-82
42-0
12-70
6-70
40-5
11-71
6-30
38-5
13-50
7-38
33-2
i4-10
7-74
33-5
13-69
6-88
36 0
16-61
8-61
Average
Evaporation
in Ins.
May-Sept.
Incl.
Not recorded
24-6
Not recorded
33-17
29-8
Not recorded
20.52
Not recorded
P/E
Ratio2
0-64
0-35
0-45
0-66
The Manyberries data are for the period 1929-1942 inclusive, while the records from the other localities
are for 21 years or more, up to and including 1942.
1 Data from Dominion Experimental Stations.
2 Ratio of total annual precipitation to evaporation during the period May to September inclusive.
The data indicate that climatic conditions differ considerably even within
the plains region. Moisture conditions are least favourable in the area south
from Medicine Hat to the International Boundary and are somewhat better in
the districts to the east, north and west of this dry section. There is a gradual
decline in mean temperatures from west to east in the whole region. A favourable
feature of the climate is the high percentage of the total precipitation which
occurs during the spring and early summer. The climate of the Manyberries area,
of particular interest in this study, is described in considerable detail in an
earlier publication (8) .
Soils
The soils of the area belong mainly in the Brown and Dark Brown zones,
although limited areas of the Black and Grey Forest types occur. Within each
zone there occur wide variations in soil texture, ranging from heavy clays to
sands, but the most prevalent types are loams. Most of the soils have been
derived from glacial material, but in some' the mantle of till is thin and
the influence of the native rock upon soil formation has been great.
The Brown soils have developed under the most arid climatic conditions in
the area and are characterized by brown or greyish-brown "A" horizons with a
low content of organic matter. A layer of calcium carbonate accumulation occurs
at an average depth of one foot or less.
The soils of the Dark BrowTn zone have "A" horizons of a dark brown
colour containing more organic matter than is found in the Brown soils. The
layer of lime accumulation is at a greater depth, occurring at 15 to 18 inches
on the average. Data on the chemical composition of typical soil series in each of
the two principal zones are presented in Table 2.
11
TABLE 2.— CHEMICAL COMPOSITION OF TYPICAL PRAIRIE SOILS IN SOUTHERN
SASKATCHEWAN
Data from Saskatchewan Soil Survey Report No. 10 (38)
Soil Zone and Series
Texture
Chemical Composition in Per Cent
pH
Nitrogen
Phosphorus
Calcium
Potassium
Brown 7one —
Sceptre
Heavy clay
0-22
0-20
016
015
0-26
0-19
0-06
0-06
0-04
0-03
007
005
1-03
0-44
0-37
0-24
0-65
0-70
1-70
1-60
1-40
1-60
1-80
1-40
8-2
Haverhill
Loam
7-9
Hatton
Fine sandy loam —
Clay loam
Echo1
6-5
Dark Brown —
Weyburn
Loam
Asquith
Fine sandy loam
All data based on analysis of the surface foot of soil.
1 The Echo series is a solonetz type developed in areas where the influence of pre-glacial material is
strong.
It will be noted that these soils are all fairly well supplied with lime and
potassium, but the nitrogen and phosphorus contents are inclined to be low,
particularly in the coarser-textured series and the solonetz soils of the Brown
zone. Most of the figures in Table 2 are applicable throughout the extent of
their respective zones in both Saskatchewan and Alberta. However, data from
soil surveys in southeastern Alberta (50,51) indicate that the nitrogen content
in this area is generally lower than shown above. In the Brown soils of this
region the average nitrogen content is approximately 0-135 per cent while that of
the Dark Brown soils is about 0-200 per cent.
The composition of soils at the Manyberries Range Station is of particular
interest in this study since so many of the plant samples were obtained in this
locality. Data for typical soils in the area are presented in Table 3.
TABLE 3— CHEMICAL COMPOSITION OF THE SURFACE FOOT OF SOILS AT THE
MANYBERRIES RANGE STATION
Texture
Chemical Composition in Per Cent
Type
Nitrogen
(Total)
Phosphorus
Potassium
PH
Total
Avail.
Total
Avail.
Upland
Sandy loam
0 150
0 095
0-110
0-063
0-062
0 051
0 020
0010
0012
0-473
0-651
0-540
0 028
0-021
0-016
7-7
Alluvial flat
Silty loam
8-2
Blowout area
Silty clajr loam
7-9
The data indicate that the sandy loam upland soils at the Manyberries
Station are fairly similar in composition to those of comparable texture in the
Brown zone generally. The alluvial soils are low in nitrogen and available
phosphorus. The soils of the blowout areas are low in fertility also, being low
in nitrogen and in available phosphorus and potassium. Blowout is the term
used to describe shallow pits formed by erosion of varying amounts of the
"A" soil horizon. These are characteristic of the Echo soil series in southern
Saskatchewan and of similar soils in southeastern Alberta.
While soils of the Brown and Dark Brown zones occupy most of the area
covered in this study, other types exist in the Cypress Hills and foothills of
the Rockies. Shallow Black, Normal Black and Grey Forest soils occur in these
12
areas, the first named being the lowest in the altitudinal series. Data on the
chemical composition of some typical foothill soils are presented in Table 4.
The figures are for the average composition of all samples within each zone,
regardless of texture. The data are calculated on the surface foot of soil.
TABLE 4.— CHEMICAL COMPOSITION OF TYPICAL ROCKY MOUNTAIN
FOOTHILL SOILS
Data from Alberta Soil Survey Reports (50, 52)
Zone
Composition in Per Cent
pH
Nitrogen
Phosphorus
Dark Brown
0-200
0-280
0-520
0 120
0-067
0-077
0-100
0-042
6-8
Shallow Black
7-0
Normal Black
6-0
Grey Forest
5-4
Both nitrogen and total phosphorus increase from the Dark Brown to the
Normal Black soils. Although the total phosphorus content of the Normal
Black soils is relatively high, the percentage of the total which is available is
much lower than in the Shallow Black, Dark Brown or Brown zones. The Grey
Forest soils are leached heavily and as a result are low in organic matter,
nitrogen and phosphorus.
The limited data available for the Black and Grey Forest soils in the
Cypress Hills indicate that they are similar in composition to those of Table 4.
Native Vegetation
The vegetation of the area consists mainly of grassland, although shrub and
forest communities occur in the sandhill regions, in the Cypress Hills and in
the Rocky Mountain Foothills. Brief descriptions of the main plant associations-
are presented in the following section. For more detailed information the reader
is referred to other publications (6, 7, 8) by the authors and co-workers, also to a
recent paper by Moss (33).
The grasslands include three main types, namely Shortgrass Prairie, Mixed
Prairie and Submontane Prairie.
Shortgrass Prairie
This association occurs under the most arid conditions found in the study
area, being associated with the drier portion of the Brown Soil zone. The
approximate extent of the area occupied by this type of vegetation is indicated in
Figure 1. There is a broad transition zone between the Shortgrass and Mixed
Prairie which makes the establishment of boundaries very difficult. Plant growth
is generally shorter in the Shortgrass Prairie than in the other two types of
grassland and productivity is lower.
The most abundant species is blue grama grass (Bouteloua gracilis).
Other dominants in order of importance are common speargrass {Stipa comata) ,
western wheatgrass (Agropyron Smithii), Junegrass (Koeleria cristata) and
dwarf bluegrass (Poa secunda) . Involute-leaved sedge (C. Eleocharis) is
abundant while niggcrwool (C. filifolia) is of frequent occurrence. Common
broad-leaved plants include pasture sage [Artemisia frigida) , dwarf phlox
(Phlox Hoodii), broom weed (Gutierrezia diversifolia) , winter fat (Eurotia
lanata), salt sage (Atriplex Nuttallii) and sagebrush {Artemisia carta). Cactus
(Opuntia polyacantha) is a characteristic species of this zone. Little clubmoss
(Selaginella densa) is abundant over much of the area, but because of its
13
low water and nutrient requirements it does not exert much influence in the
association. The five grasses and two sedges listed above compose about
80 per cent of the total plant cover, little clubmoss excluded.
Mixed Prairie
This type is associated with better moisture conditions than those found in
the Shortgrass Prairie, and is the dominant association in the Dark Brown Soil
zone and the moister portions of the Brown Soil zone. The more favourable
climatic conditions are reflected in the development of a richer flora and taller
growth than that occurring in the shortgrass type.
The principal species are short- awned porcupine grass (Stipa spartea var.
curtis eta) , common speargrass, northern wheatgrass (Agropyron dasystachyum) ,
western wheatgrass, Junegrass, grama grass, involute-leaved sedge and sun-
loving sedge (Carex heliophila) . Green speargrass (Stipa viridula) and rough
fescue {Festuca scabrella) are common in favoured locations. Pasture sage
and broom weed are the principal forbs.
It is evident that most of the dominants of the Shortgrass zone extend into
the Mixed Prairie, but that they are supplemented and often exceeded in
abundance by plants not common in the former type.
Shrubs are more common than in the Shortgrass zone and include a greater
variety of species. The principal forms are wild roses (Rosa spp.), snowberry
(Symphoricarpos occidental-is) and wolf willow (Elaeagmis commutata) . Trees,
mainly aspen poplar (Populus tremuloides) and willows (Salix spp.) occur in
spots where moisture conditions are better than average.
Submontane Prairie
This association occurs adjacent to the Mixed Prairie at higher altitudes in
the Cypress Hills and Rocky Mountain Foothills. It is associated with cooler
Figure 2. — Typical stand of mixed prairie. Speargrasses. Junegrass and wheatgrasses are the
principal species. "Note patches of the shrub, Western snowberry, in the background.
14
and slightly moister conditions than those under which Mixed Prairie is
developed. It occurs on soils of the Black zone and may develop on Shallow
Black soils also (33).
Figure 3. — Range types in the Rocky Mountain Foothills. Submontane prairie in foreground
with forest range on higher ground close to the mountains. Willows are common
in lower-lying parts of the grassland.
The principal species is rough fescue, while Idaho fescue {Festuca idahoen-
sis) , wild oatgrass (Danthania intermedia) and Parry's oatgrass (D. Parryi)
often are abundant. Junegrass, northern wheatgrass, awned wheatgrass (Agro-
vyron trachycauhim var. unilaterale) , short-awned porcupine grass and Hooker's
oatgrass {Avena Hookeri) are common. Forbs are relatively abundant and
include species of hedysarum, lupine and wild geranium. The principal shrubs
are shrubby einquefoil (Dasivhora fruticosa), wild roses and snowberry. Aspen
poplar and willows occur in low spots and on sheltered slopes.
Vegetation of Sandhill Areas
In the Great Sandhills and other smaller areas where sand dune formation
1ms occurred there is considerable variation in plant cover, mainly in response
to differences in soil moisture conditions.
On areas where the water-table is at a considerable depth, the vegetation
consists mainly of grassland. Many of the species found in the prairie associa-
tions, such as common speargrass, grama grass, Junegrass, involute-leaved
<edgc, pasture sage and smooth goldenrod (Solidago glaberrimct) are abundant.
In addition, several plants occur which are characteristic of sandy soils. These
include sandgrass (Calamovilfa longifolia) , sand dropseed (Sporobolus cryp-
tandrus) , Indian ricegrass (Oryzopsis hyinctioidos) and Canada wild rye
(Elymus canadensis) . Sand dock (Rimiex venosus) , lance-leafed psoralea
(Psoralid'nnn lanceolatum) and Fendler's cryptanthe (Cryptantha Fendlcri) are
characteristic sandhill forbs.
15
Where moisture conditions are more favourable, a shrub association
develops. The principal species are Macoun's rose (Rosa Macounii) , chokecherry
(Prunus melanocarpa) , wolf willow, sagebrush, snowberry and creeping juniper
(Sabina horizontalis) . The herbaceous cover consists of a mixture of forbs
and grasses, including pasture sage, smooth goldenrod, sand dropseed, sandgrass,
Canada wild rye and involute-leaved sedge.
Figure 4. — Typical sandhill vegetation. Common speargrass &nd sandgrass make up the bulk
of the grass cover shown here, while chokecherry (dark in photo) and willows
(lighter coloured) are the principal shrubs.
Under still more favourable moisture conditions, trees and tall shrubs occur.
The principal species are aspen poplar, balm-of-Gilead (Popalus tacamahacca
var. candicans) , several species of willow including Bebb's willow (Salix Beb-
biana) and sandbar willow (8. interior), river birch (Betula fontinalis) and
chokecherry. This tree growth may occur as scattered clumps in depressions
among shrubs or grassland or may form extensive stands in areas where
climatic conditions are more favourable.
Forest Vegetation
Tree growth constitutes an important part of the native vegetation in the
Cypress Hills and in the Rocky Mountain Foothills. In both areas two main
types of forest cover occur, namely, the aspen grove association along the upper
border of the grassland, and coniferous forest at higher altitudes.
The aspen grove type consists of clumps of trees, mainly aspen poplar,
intermingled with grassland of the Submontane Prairie association. Willows
and black poplar {Populus tacamahacca) occur in moist spots within this type.
Shrubs include wild roses, snowberry and saskatoon [Amelanchier alnijolia).
Common herbaceous species include awned wheatgrass, fringed brome [Bromus
ciliatus) , mountain brome (B. marginatus) , pea-vine (Lathyrus ochroleucxis)
and American vetch (Vicia americana) .
28428—4
16
The coniferous forest is dominated mainly by white spruce {Picea glauca)
and lodgepole pine (Pinus contorta var. latifolia). Spruce is the principal
climax species, but as a result of repeated fires, large areas are occupied at
present by nearly pure stands of pine. Other common trees include aspen poplar
and willows. Shrubs include low buffalo berry (Shepherdia canadensis) , dwarf
spiraea (Spiraea lucida) and wild rose. The herbaceous cover is dominated
usually by pinegrass (Calamagrostis rub esc en s) , bearberry (Arctostaphylos Uva-
ursi) and twinflower {Linnaea americana) . Species wThich are common, particu-
larly where the tree cover is fairly open, include awned wheatgrass, fringed brome,
pea- vine and American vetch.
The type of coniferous forest described above includes both the Mixedwood
and Foothills sections of the Boreal Forest as described by Halliday (22).
The aspen grove type corresponds to the section of the same name under his
Boreal Forest classification. The Subalpine Forest type which occurs at higher
elevation in the foothills was not included in the present study.
METHODS OF STUDY
In collecting, pure samples of each species in one growth stage were
obtained usually, composite sampling being used only in special cases. Col-
lections were made according to stages of development rather than by chro-
nological dates. Differences in composition among species and among different
growth stages of any one species rendered this procedure necessary in order to
obtain data which could be applied to actual range conditions. Samples were
taken in such a manner as to simulate actual grazing as closely as possible.
Highly palatable grasses were clipped closely, while only the current year's
growth of shrubby species was taken.
Samples at the Manyberries Station were taken from sites selected as
representative for the species, and the same sites were used each season.
When collecting in other localities it was not always possible to establish definite
sites, but every effort was made to obtain samples from representative areas.
Within each site, the clippings composing any one sample were taken at random
over the area and then composited. Clipping of the mature growth on sites in
late fall or very early spring was found- to facilitate greatly the task of obtaining
pure samples of current growth during the following season.
All material was air-dried as quickly as possible, and forwarded to the
Division of Chemistry, Science Service. Ottawa, for chemical analysis. The
standard feeding stuffs determination of crude protein, crude fibre, ether extract,
total ash and nitrogen-free extract was made. In addition, the phosphorus and
calcium content was determined for all samples collected after 1928. Silica
content was determined for a limited number of samples.
REVIEW OF LITERATURE
During the past two decades particularly, numerous studies have been
reported dealing with the chemical composition and nutritive value of pasture
herbage in many parts of the world. In general these researches may be
divided into two main groups, first those dealing with highly productive pastures,
often sown to cultivated species in relatively humid areas, and second, those
dealing with grazing lands of relatively low productivity in semi-arid and arid
areas where the bulk of the forage consists of native species. The present study
belongs to the second group.
Studies of the chemical composition and nutritive value of native forages
and of deficiencies occurring in them have been numerous in the Western United
States, South Africa and Australia. Reviews of the literature have been pub-
lished by Gordon and Sampson (19), Watkins (46) and others. No attempt
17
will be made here to mention more than a few studies which have a bearing on
the present work. Other references dealing with particular phases of the
problem will be introduced in the sections to which they are pertinent.
A number of studies of the changes in chemical composition occurring during
the seasonal development of range forage species have been reported. Gordon
and Sampson (19), found that in herbaceous plants on California ranges there
was an orderly decline in the percentage of crude protein, silica-free ash,
calcium, phosphorus and potassium during seasonal development. Crude fibre
increased with the advance of the season. The most rapid changes in con-
stituents occurred during the period front early leaf to full bloom.
Hopper and Nesbitt (25) in North Dakota present data for native and
cultivated forages of their region which indicate that crude protein decreased
with seasonal development, while crude fibre and nitrogen-free extract increased
and total ash and ether extract showed no definite trend.
Stanley and Hodgson (41) found declines in protein and phosphorus and
increases in nitrogen-free extract and crude fibre during the seasonal develop-
ment of Arizona range grasses. Total ash and ether extract showed no definite
trends.
Fraps and Fudge (18) working with range forages in East Texas found that
protein and phosphorus declined regularly with seasonal development while
crude fibre and nitrogen-free extract increased. Lime usually decreased but the
tendency was irregular in many species.
McCall (31) found that with bluebunch fescue (Festuca idahoensis) in the
state of Washington, seasonal trends in composition were very marked. Crude
protein and phosphorus declined greatly with increasing maturity, crude fat and
calcium declined to a lesser degree, while fibre increased greatly.
Deficiences of certain minerals, particularly phosphorus, have been reported
for pasture areas in many parts of the world. Theiler and co-workers (44)
found the phosphorus content of native pastures in South Africa to be very low,
and proved that certain diseases of livestock were caused by lack of this
mineral. Phosphorus deficiencies have been reported for areas in both Australia
and New Zealand, while a lack of iron occurs in certain parts of the latter
country. In the United States, phosphorus deficiences haA^e been found in
Florida, Minnesota, Montana (39), New Mexico (46), Texas and other states.
In Canada, the native forage in parts of Manitoba (17) and the Shortgrass
Prairies of southern Alberta and Saskatchewan (6, 46) has proved to be low in
phosphorus.
Beneficial results from feeding supplemental minerals have been reported
by many workers. The feeding of additional phosphorus, a practice pioneered in
South Africa, has been found advantageous by many workers including Dutoit
and co-workers (16) in South Africa, Black and co-workers (3) in Texas and
Knox and Watkins (28) in New Mexico.
The relation of the digestibility and nutritive value of pasture species to
their chemical composition has been studied considerably in recent years.
Several workers, including Crampton (10) and Maynard (29) have pointed out
discrepancies between the results of chemical analysis and actual feeding tests.
These workers, along with Christensen and Hopper (9), Burkitt (4), Sotola
(39, 40) and others found that the digestibility of all nutrients in pasture herbage
decreases with the advance of the season and approach of maturity. !
effects of seasonal changes in the quantity of the various nutrients, as revealed
by chemical analysis, are thus intensified by changes in their quality. The
importance of total digestible nutrients as well as of digestible protein content
in cured range forage has been pointed out by Stanley and Hodgson (42).
Norman (34) and others have shown the high nutritive value of carbohy-
drates of young grass, including the crude fibre fraction. The importance of
28428—44
18
lignin, as influencing the digestibility of other fractions, especially cellulose,
has been stressed (10, 34). Revised methods of chemical analysis involving the
determination of lignin and cellulose have been suggested for pasture forages
(10, 11, 29). Preliminary tests by Crampton and Forshaw (11) in Quebec and
Patton and Griseker (35) in Montana indicate the possibilities of these newer
analytical methods in obtaining results more in accord with the results of
actual feeding trials.
THE CHEMICAL COMPOSITION OF PRINCIPAL FORAGE SPECIES
The data obtained in this study are presented separately for the main
range types of the area, including Shortgrass Prairie, Mixed Prairie, Sandhill
Vegetation, Submontane Prairie and Forest. Two groups of plants not associated
with any particular zone; namely meadow species and cultivated grasses are
treated in additional sections. Since the majority of samples were collected in
the shortgrass association, the data for this community are presented first and in
greatest detail.
Shortgrass Prairie Species
Samples were collected mainly at the Manyberries Range Station although
some collections were made in other parts of the Shortgrass area. In the case
of dominant species, samples were obtained in each of the principal growth
stages for a period of several years. The object was to obtain a detailed know-
ledge of the composition of these key species, including differences due to growth
stage and to variations in climatic conditions from year to year. For plants
of secondary importance, enough samples were secured to enable a comparison
to be made with the principal species.
For the purposes of convenience in presenting the data, the forage plants of
the Shortgrass Prairie are divided here into the following three groups:
(1) Principal grasses and grass-like plants
(2) Grasses and grass-like plants of secondary importance
(3) Forbs and shrubs.
19
Principal Grasses and Sedges
It has been found (8) that five species of grass and one sedge constitute
about 80 per cent of the plant cover and 90 per cent of the forage on typical
shortgrass prairie range. Due to its great importance, this group was studied in
more detail than any other. A summary of the data is presented in Table 5.
TABLE 5.— CHEMICAL COMPOSITION OF PRINCIPAL GRASSES OF SHORT-GRASS
PRAIRIE
Species and Growth
Stage
No. of
Samples
Av. Date
Collected
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen
Free
Extract
Total
Ash
Cal-
cium
Phosph
orus
Grama grass
( Bouteloua gracilis) —
Leaf
Flower
Medium seed1
Cured
After winter exposure .
Common speargrass
(Stipa comata) —
Leaf
Flower
Medium seed
Cured
After winter exposure .
Western wheatgrass
( Agropyron Smithii) —
Leaf
Flower
Medium seed
Cured
After winter exposure .
Junegrass
(Koeleria cristata) —
Leaf
Flower :
Medium seed
Cured
After winter exposure.
Dwarf bluegrass
(Poa secunda) —
Leaf
Flower
Medium seed
Cured
After winter exposure.
Nigger wool
(Car ex filijolia)—
Flower
Medium seed
Cured
9
11
10
7
3
13
6
8
4
5
10
6
4
2
June 19
July 26
Aug. 14
Oct. 13
Apr. 10
May 23
June 24
July 11
Oct. 13
Apr. 9
May 31
July 3
July 18
Oct. 20
Apr. 12
May 11
June 17
July 5
Oct. 5
Apr. 5
May 10
May 28
July 7
July 11
Apr. 3
Apr. 29
May 29
Sept. 20
14-85
9-52
7-46
5-22
5-00
18-87
9-80
8-26
4-87
3-65
17-35
10-76
7-79
3-80
3-58
20-30
8-62
6-57
4-60
4-28
20-27
10-47
5-95
5-24
3-10
18-14
14-48
6-65
24-80
30-48
30-94
30-46
31-91
24-20
30-22
33-58
33-77
35-48
27-84
33-21
34-10
33-50
33-81
23-34
33-50
34-24
35-86
35-77
24-69
33-27
35-44
38-38
38-26
22-64
24-25
29-75
~(2)
1-43
2-03
1-53
2-62
2-37
2-61
2-28
1-46
2-65
2-34
2-06
205
1-26
3-46
2-74
2-83
1-64
0-97
50-97
53-15
54-05
46-39
53-01
50-20
51-66
52-66
43-81
46-29
49-32
51-09
49-75
42-54
48-21
47-92
48-85
50-16
2-96
3-60
47-15
48-37
1-20
51-36
3-28
3-34
50-63
50-46
8-94
7-24
6-42
8-74
10-62
7-92
4-63
5-10
7-42
6-75
8-36
7-40
6-73
9-56
11-60
10-36
6-93
8-44
9-05
8-82
9-68
6-15
6-64
5-14
6-08
7-66
7-36
9-80
0-459
0-330
0-357
0-353
0-413
0-376
0-258
0-293
0-440
0-320
0-375
0-285
0-220
0-381
0-462
0-409
0-270
0-343
0-315
0-360
0-332
0-240
0-242
0-230
0-250
0-437
0-433
0-585
0-188
0-180
0-147
0-120
0-073
0-258
0-191
0-148
0-078
0-070
0-217
0-156
0-132
0-060
0-046
0-268
0-178
0 126
0-075
0-070
0-336
0-202
0115
0-076
0-050
0-220
0-180
0 079
The data in this and all succeeding tables are calculated on a dry matter basis unless stated otherwise.
1 "Medium seed" equals seed in the early dough stage.
2 Dashes indicate — No determination made.
The data indicate general similarity in the composition of the grasses,
although differences do occur in the case of certain constituents in some growth
stages. For example, the protein and phosphorus content of samples in the leaf
stage is higher in early species such as Junegrass and dwarf bluegrass than in
the late developing grama grass. This difference disappears by the time the
flowering stage is reached.
20
Niggerwool, the one sedge included in Table 5 tends to be richer in protein,
ether extract and calcium and lower in crude fibre than the grasses.
It is evident that changes in chemical composition at different growth stages
were generally much greater than differences between species in the same
growth stage. The percentage of most constituents changed greatly from the
early leaf to the cured stage, and even in the dry forage during winter.
These changes in composition due to growth development are brought out more
clearly in Table 6 in which data for the grass species of Table 5 have been
averaged.
TABLE 6.— AVERAGE CHEMICAL COMPOSITION OF FIVE MAIN GRASSES OF SHORT-
GRASS PRAIRIE
No. of
Samples
Chemical Composition in Per Cent
Calcium:
Phosph-
orus
Ratio
Growth Stage
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen
Free
Extract
Total
Ash
Cal-
cium
Phosph-
orus
Leaf
39
18
50
36
33
18
18-33
13-10
9-83
7-21
4-85
402
25-0
29-2
32-1
33-7
34-5
35-4
2-57
2-79
2-37
2-64
1-87
1-26
45-7
47-8
49-1
49-7
51-7
50-8
9-05
7-53
6-47
6-66
8-37
8-73
0-390
0-274
0-277
0-291
0-337
0-361
0-252
0-206
0-181
0-134
0-084
0-062
1-5:1
Emerging from sheath . .
Flower
1-3:1
1-5:1
Medium seed
2-2:1
Cured
After winter exposure. . .
4-0:1
5-8:1
Comparison of these average data with those for the individual species
indicates that there is a strong similarity in the changes occurring in each of the
f\ve species during growth development.
The crude protein content is highest in the leaf stage and drops sharply as
growth development proceeds, reaching a minimum in the cured forage collected
in the following spring.
Crude fibre varies in an opposite manner to protein, increasing with each
successive growth stage. The percentage of nitrogen-free extract increases, also,
but to a much smaller degree.
The content of ether extract remains relatively constant during the earlier
growth stages but declines when curing occurs and becomes still further reduced
over winter.
The trend for phosphorus is similar to that for protein, there being a decline
throughout the whole period of growth development.
The* calcium content exhibits a trend different from that shown by other
constituents. It is at a maximum in the leaf stage and after winter exposure
and lowest during emerging and flowering. While this course is indicated clearly
by the average data, it was not followed closely by all five species. In spear-
grass there was a decided drop in calcium content over winter, while in
western wheatgrass the minimum occurred in the seed stage.
The calcium-phosphorus ratio is relatively low and constant in the earlier
growth stages but increases from the time of seed production and reaches a
maximum after winter exposure.
The percentage of total ash shows a seasonal curve, with the low point
occurring during the flowering stage. Data for silica-free ash obtained during two
years of the study show that this apparent trend is due to the silica content.
Data for total and silica-free ash in three of the five major grass species are
presented in Table 7.
21
TABLE 7.— AVERAGE ASH CONTENT OF THREE IMPORTANT SHORTGRASS PRAIRIE
SPECIES1
Growth Stage
Composition in Per Cent
1 The data are averages for common speargrass, grama grass and Junegrass.
It is evident that there is a steady seasonal decline in silica-free ash. Silica,
which is of no value in animal nutrition, is abundant in these grasses, and its
presence masks the trend of the other mineral elements when no separate
determination of silica-free ash is made.
Grasses of Secondary Importance
There are several native grasses which occur commonly in the Shortgrass
Prairie area but which are not sufficiently abundant to rank with the dominant
species discussed previously. Some are scattered throughout the uplands, while
others are localized in areas where conditions of soil moisture, salt concentration,
etc., differ from those prevailing in the zone generally. These species may con-
tribute a considerable proportion of the grazing in certain areas or at certain
seasons of the vear. The data for some of these forms are summarized in
Table 8.
TABLE 8.— CHEMICAL COMPOSITION OF GRASSES OF SECONDARY IMPORTANCE IN
SHORTGRASS PRAIRIE
Species
Stage of
Growth
Av. Date
Collected
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Ether
Extract
Cal-
cium
Phosph-
orus
A — Plants of Non-saline
Prairie —
Plains reedgrass
(Calamagrostis montanensis). .
Prairie muhlenbergia1
(Muhlenbergia cuspidata)
Canby's bluegrass
(Poa Canbyi)
Leaf
Flower
Flower
Leaf
Flower
Seed
Leaf
Flower
Flower
Flower
May 22
June 27
May 29
June 30
June 4
July 16
Aug. 10
May 24
June 26
June 28
July 6
2
2
2
2
5
4
3
4
4
3
2
11-90
8-56
11-30
7-30
1510
10 18
7-50
23-98
10-40
10-88
5-90
27-96
32-06
26-32
36-50
2701
29-08
28-83
26-74
32-24
31-19
39-54
3-56
3-91
2-65
2-68
2-54
209
3-98
1-96
0-261
0-246
0-390
0-190
0-248
0-225
0-210
0-428
0-238
0-213
0-310
0-187
0-153
0166
0-205
B — Plants of Saline Areas —
Saltgrass
(Distichlis stricta)
0194
n <<
0 153
a <<
0 092
Wild barley2
( Hordeum jubatum )
0-346
it U i:
0-216
Nuttall's alkali grass
Alkali cordgrass
(Spartina gracilis)
0-217
0153
1 Occurs mainly on eroded slopes.
2 Common on abandoned fields as well as saline areas.
22
Considerable differences occur among the different species, but not to any
extent between the two ecological groups. Most of the plants of Table 8 contain
slightly less protein and phosphorus in the leaf stage than do the grasses of
Tables 5 and 6. This difference disappears largely in subsequent growth stages.
The protein content of wild barley (''foxtail") in the leaf stage is actually
much higher than that of the dominant upland grasses. On the other hand,
prairie muhlenbergia and alkali cordgrass are inferior to the species of Table 5
in content of protein and minerals. The fat content of most plants of Table 8
is as high or higher than that of the dominant upland grasses. Determinations
of total ash and nitrogen-free extract were made for a few of the secondary
species. The data, not presented here, are in general agreement with those for
the grasses of Table 5.
Broad-Leaved Species
While the greater part of the forage of shortgrass prairie ranges is composed
of grasses and sedges, there are several broad-leaved herbs and shrubs which are
of considerable value for grazing. The most important species of this group are
salt sage and winter fat. Data for these two plants are presented in Table 9.
TABLE 9.— CHEMICAL COMPOSITION OF PRINCIPAL BROAD-LEAVED FORAGES OF
SHORTGRASS PRAIRIE
No. of
Samples
Av. Date
Collected
Chemical Composition in Per Cent
Species and Stage
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
• Cal-
cium
Phosph-
orus
Salt sage
(Atriplex Nuttallii) —
Leaf
6
7
6
6
7
7
4
5
May 28
July 1
July 24
Oct. 7
May 26
June 28
July 23
Oct. 15
23-43
16-50
16-35
10-35
21-95
18-30
16-00
11-23
11-53
16-81
19-38
24-46
25-25
28-28
28-88
27-65
2-49
2-15
1-55
2-20
2-06
2-50
39-03
43-70
45-16
50-81
39-07
41-07
23-52
20-84
17-56
12-18
11-67
9-85
8-47
7-97
1-064
1-020
1-202
1-458
0-893
0-924
0-835
1-494
0-476
Flower
0-244
Medium seed
0-155
Cured
Winter fat
(Eurotia lanata) —
Leaf
0-103
0-298
Flower
Medium seed
0-229
0-216
Cured
107
52-08
0-093
It is evident that winter fat and salt sage contain more protein and minerals
and less crude fibre than do the principal grasses in comparable growth stages.
The calcium content is particularly high in comparison with that of the grass
species. As a result, the ratio of calcium to phosphorus is higher than in the
major grass species, particularly in the later growth stages.
The changes in chemical composition associated with growth development
are much the same as in the grasses, although it is noteworthy that protein
content does not decline so sharply in the broad-leaved species. The percentage
of crude fibre in winter fat, while relatively high in the leaf stage, does not
increase to such an extent in subsequent growth stages as in most grasses. The
fibre content of salt sage is relatively low in all stages.
The broad-leaved forages of secondary importance were studied less fully
than were winter fat and salt sage. The data are presented in Table 10.
23
TABLE 10.— CHEMICAL COMPOSITION OF FORBS AND SHRUBS OF SECONDARY
IMPORTANCE
Species
Pasture sage
(Artemisia frigida)
Sagebrush
(Artemisia cana)
Ascending milk vetch
(Astragalus striatus)
Spreading homalobus
( Homalobus tenellus)
Narrow-leaved vetch1
(Cnemidophacos pectinatus)
Two-grooved milk vetch1
(Diholcos bisculcatus)
Russian thistle
(Salsola Pestifer)
U ((
« tt
Greasewood2
(Sarcobatus vermiculatus).. .
Western sea blite2
(Suaeda depressa)
Stage of
Growth
Leaf. .-.
Cured.
Leaf
Cured.
Flower.
Flower.
Flower.
Flower.
Leaf. . . ,
Flower.
Seed . . .
Flower.
Flower.
Av. Date
Collected
May 25
Oct. 21
May 26
Oct. 16
June 6
June 28
May 28
June 3
June 23
Aug. 14
Sept. 3
Aug. 2
Aug;. 2
No. of
Samples
Crude
Protein
18-16
7-58
19-29
9-52
22-47
17-66
24-00
20-11
21-30
18-00
10-72
19,50
16-30
Crude
Fibre
27
33
24
23
21
24
19
23
11
23
24
IS
14
Ether
Extract
5-79
3-07
2-86
3-17
2-53
1-87
1-85
2-85
Cal-
cium
0-810
0-620
0-710
0-970
1031
0-748
0-828
2-494
1-800
1-503
0-190
0-260
Phos-
phorus
340
110
450
221
256
272
413
258
301
200
213
190
100
1 These species may^be poisonous to livestock due to high selenium content when growing on soils rich
in this mineral.
2 Plants of saline soils.
The analyses indicate that these species, like those of Table 9, are generally
superior to the grasses in percentage of protein and minerals and lower in
crude fibre content. In addition, pasture sage and sagebrush have an exceptionally
high fat content, even when in the cured stage. The legumes, as might be
expected, are richer in protein than are most other plants. The leafage of
Russian thistle is high in protein and very low in fibre. The calcium phosphorus
ratio is high in most species of Table 10.
The data available indicate that the high ash content of the broad-leaved
species of Tables 9 and 10 is not in most cases associated with a high percentage
of silica. Only salt sage and Russian thistle equal the grasses of Table 7 in
silica content.
28428 -5
24
Mixed Prairie Species
The principal forage plants of the Mixed Prairie include many species such
as western wheatgrass, common speargrass, Junegrass and grama grass which are
abundant in the Shortgrass Prairie. The chemical composition of these plants
was discussed in a previous section. Other plants such as short-awned porcupine
grass and northern wheatgrass are associated more particularly with mixed
prairie vegetation, and it is species of this latter group which are treated in the
present section. Since the study* of mixed prairie forages was begun only
recently, the data are not so complete as for the shortgrass prairie species.
Analytical results for the principal plants are summarized in Table 11.
TABLE 11.— CHEMICAL COMPOSITION OF CERTAIN COMMON GRASSES OF
MIXED PRAIRIE
No. of
Samples
Av. Date
of Collec-
tion
Chemical Composition in Per Cent
Species and Stage
of Development
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
Cal-
cium
Phos-
phorus
Northern wheatgrass
( Agropyron dasystach-
yum) —
Leaf
3
2
2
3
2
2
2
2
2
May 30
June 22
Oct, 18
June 10
July 10
May 26
June 22
July 23
May 18
16-06
11-82
4-10
16-17
9-82
25-50
13-56
8-50
15-70
26-65
33-48
36-66
25-15
33-84
21 00
32-34
35-52
25-92
3-30
2-48
3-00
2-82
1-86
47- 19
45-67
46-59
47-78
47-52
6-80
6-55
9-49
8-08
6-96
10-66
9-16
7-61
10-36
0-300
0-350
0-530
0-373
0-398
0-450
0-420
0-400
0-575
0-210
Late leaf
0-160
Cured
Short-awned porcupine
grass
(Stipa spartea var.
curtiseta) — ■
Leaf
Flower
Green speargrass
(Stipa viridula) —
Leaf
0 070
0-203
0-137
0-245
Flower .
0-160
Medium seed
1-78
46-59
0-150
Skyline bluegrass
(Poa Cusickii) —
Leaf
0-245
The available data indicate that the composition of the two most abundant
species, northern wheatgrass and short-awned porcupine grass, is much the same
as that of the principal shortgrass prairie species {see Tables 5 and 6). Green
speargrass, on the other hand, tends to have a higher content of protein and
calcium. The phosphorus content of most of the species of Table 11 is slightly
lower than that of the main shortgrass prairie forms.
The changes in composition of mixed prairie forages with growth develop-
ment appear to be much the same as in shortgrass prairie species, although the
number of stages studied is not sufficient to provide for detailed comparison.
The drop in protein and phosphorus with successive growth stages does not
seem to be so rapid as for the shortgrass prairie forages.
25
Submontane Prairie Species
The native forages of the Submontane Prairie include not only many species
characteristic of this zone but also a number which are abundant in Shortgrass
and Mixed Prairie. The chemical composition of the principal species of this
latter group, including Junegrass, northern wheatgrass and short-awned porcupine
grass was discussed previously. Only species confined more or less to Submontane
Prairie are considered in the present section. The data for grasses are presented
in Table 12.
TABLE 12.— CHEMICAL COMPOSITION OF PRINCIPAL GRASSES OF SUBMONTANE
PRAIRIE
Species
Rough fescue
(Festuca scabrella)
a a
n a
a a
a u
Idaho fescue
(Festuca idahoensis )
<< u
Awned wheatgrass
( Agropyron trachycaulum var
unilaterale)
Wild oatgrass
(Danthonia intermedia)
a u
Hooker's oatgrass
(Avena Hookeri)
Short-awned brome
(Bromus breviaristatus)
Growth
Stage
Leaf
Late leaf..
Flower... .
Medium
seed ....
Seed shed
partly
cured. . .
Leaf
Flower. . .
Medium
seed.
Leaf. . .
Medium
seed
Flower
Leaf.. .
Flower
Av. Date
Collected
June 16
July 21
June 26
July 13
Aug. 10
June 19
July 10
Aug. 16
July 13
July 28
July 12
June
July
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
12-00
8-83
8-58
8-40
5-40
12-51
8-45
9-90
10-80
6-78
9-76
20-80
9-87
Crude
Fibre
30-25
31-71
3315
34-95
37-16
32-40
33-36
35-12
32-05
34-38
34-90
23-80
33-75
Total
Ash
10-14
10-06
11-42
8-49
9-80
9-96
8-04
5-70
9-14
7-26
8-76
10-20
9-38
Cal-
cium
0-300
0-295
0-185
0-275
0-294
0-353
0-318
0-240
0-269
0-236
0-440
0-490
0-470
Phos-
phorus
0-185
0-135
0-180
0-132
0-084
0-208
0 145
0-120
0-175
0-098
0-290
0-400
0-260
Rough fescue, the principal forage species of Submontane Prairie is relatively
low in protein and phosphorus and high in fibre when in the leaf stage. Its
composition in subsequent growth stages is more comparable to that of the
principal grasses of Shortgrass and Mixed Prairie. A somewhat similar condition
occurs in Idaho fescue. Wild oatgrass is low in protein and phosphorus in all
stages, and high in fibre when in leaf. Analysis of a single sample of Parry's
oatgrass, not included in Table 12, indicates that the two oatgrasses probably are
similar in chemical composition.
The available data for awned wheatgrass, Hooker's oatgrass and short-awned
brome indicate that these species compare favourably in composition with the
common grasses of other prairie zones.- The latter two species are particularly
rich in phosphorus.
Determination of ether extract made in a few cases, but not shown in Table
12, gave results comparable to those for common grasses of the Shortgrass and
Mixed Prairie.
Changes in chemical composition with growth development follow apparently
the same general course as for grasses in other zones. However, the decline in
protein and phosphorus and increase in crude fibre are generally not so rapid as
for the principal species of Shortgrass Prairie. This appears to be associated
with the fact that curing of leafage occurs later in the growth development of
submontane species than for those of drier areas.
28428—5.}
26
In addition to grasses, several palatable broad-leaved herbs and shrubs
occur commonly in Submontane Prairie. Data on the composition of some of the
more important species are presented in Table 13.
TABLE 13— CHEMICAL COMPOSITION OF BROAD-LEAVED FORAGE SPECIES,
SUBMONTANE PRAIRIE
Species
Growth
Stage
Av. Date
Collected
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phosph-
orus
American hedysarum
( Hedysarum americanum)
n a
<( it
Richardson's geranium
(Geranium Richardsonii )
Silvery lupine
(Lupinus argenteus )
Leaf
Flower
Seed
Flower
Flower
Flower... .
Flower —
June 7
July 4
Aug. 3
July 28
July 14
July 14
July 13
2
5
3
2
7
2
2
24-08
18-00
16-40
14-18
21-12
8-88
12-32
13-00
26-37
27-92
20-06
23-08
25-69
18-37
5-67
5-50
602
7-96
9-56
8-19
5-56
0-825
0-936
1-172
1005
1-587
1-220
0-552
0-370
0-235
0-185
0-347
0-312
Northern bedstraw
(Galium boreale)
0-190
Shrubby cinquefoil
( Dasiphora fruticosa)
0-218
It is evident that these broad-leaved plants have a higher content of protein
and minerals and less crude fibre than do most grasses in comparable stages.
Most of the species of Table 13 are rich in calcium and some, such as wild
geranium and lupine are high in phosphorus content.
Sandhill Species
Sandhill vegetation in the area studied is quite variable, comprising several
associations and including species of grasses, forbs, shrubs and trees. However,
the majority of the forbs and many of the shrubs and trees are not palatable to
livestock. The forage species may be divided into the following main groups: —
(1) Species confined more or less to sandy areas.
(2) Plants which occur on both medium-textured and sandy soils.
The present section deals mainly with species of the first group. Data for the
principal sandhill forages are presented in Table 14.
TABLE 14.— CHEMICAL COMPOSITION OF COMMON SANDHILL FORAGE SPECIES
No. of
Samples
Av. Date
Collected
(Chemical Composition in Per Cent
Species and Stage
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
Cal-
cium
Phos-
phorus
Sandgrass
(Calamovilfa longifolia)
Leaf
4
2
2
2
2
2
4
2
June
July
Nov.
June
Oct.
June
July
July
9
30
1
26
8
30
16
29
11-41
6-66
3-89
10-98
506
10-78
7-30
916
33-63
34-64
33-50
32-90
37-30
32-44
34 12
34-91
1-92
2-00
1-18
47-08
51-18
56-11
5-96
5-52
5-33
7-08
5-76
6-44
6-01
4-44
0-256
0-247
0-465
0-355
0-230
0-490
0-440
0-230
0-216
Flower
0-180
Cured
0-130
Sand dropseed
(Sporobolus cryptandrus )
Leaf
0-225
Cured
1-54
50-34
0 092
Indian rice
(Oryzopsis hymenoides )
Flower
0-180
Medium seed
2-11
2-54
50-46
49-38
0 145
Canada wild rye
(Elymus canadensis) —
Flower
0-220
27
No. of
Samples
Av. Date
Collected
Chemical Composition in Per Cent
Species and Stage
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
Cal-
cium
Phos-
phorus
Little bluestem
( Andropogon scoparius)
Medium seed
2
2
2
2
2
Aug. 19
June 27
June 28
June 27
June 27
3-96
14-48
9-57
11-19
17-57
39-89
11-56
15-80
19-36
22-91
2-31
49-42
4-42
6-92
5-10
7-08
6-42
1-890
1-350
1-990
1-200
0-051
Chokecherry
(Prunus melanocarpa ) —
Leaves and young
shoots
0-200
Sandhill rose
(Rosa Macounii)
Leaves and young
shoots
0-170
Sandbar willow
(Salix interior)
Leaves and young
shoots
0-210
Lance-leaved psoralea
(Psoralidium
lanceolatum)
Leaf
0-190
In their earlier growth stages, two of the principal species, sandgrass and
sand dropseed have lower contents of protein and phosphorus and higher amounts
of crude fibre than the main grasses of normal prairie {see Tables 5, 6, 11).
These differences are much less marked in the cured stage. Little bluestem is
decidedly low in protein and phosphorus and high in crude fibre in the seed stage.
Two other species, Indian rice and Canada wild rye have much the same
composition as the grasses of finer soils. All the sandhill grasses appear relatively
low in percentage of total ash. Analysis of silica content was made for a few
samples. The data, not shown in Table 14, indicate no appreciable difference
between sandhill grasses and those of normal prairie in silica content.
Leaves and young shoots of chokecherry and willow collected at the end of
June were higher in protein and minerals and lower in fibre than most of the
grasses at this date, when the latter were in sheath or flower. Similar material
of Rosa was relatively low in protein and phosphorus compared to the other
shrubby species. Lance-leaved psoralea was relatively low in protein and
phosphorus for a legume.
The data in Table 14 indicate that changes in chemical composition
associated with growth development are probably much the same in sandhill
plants as in those of normal prairie. There may be exceptions to this, as in the
case of sandgrass, where the content of crude fibre apparently remains relatively
constant from the leaf to the cured stage.
As noted earlier in this section, several important species occur both on
sandy and medium textured soils. The most abundant grass of this type in
sandhill areas is common speargrass, while Junegrass, wheatgrasses and grama
grass are common. Comparison of these species grown on loam prairie soils and
in sand indicates that the principal difference is in phosphorus content which is
lower in the latter case. The data are presented in a subsequent section under
the title "Effects of Soil Type on Chemical Composition".
On the whole it appears that many forage plants of the sandhills tend to
have a lower content of protein, total ash and particularly phosphorus than have
the principal species of normal prairie. More study of the composition of plants
growing in sandy areas is needed to determine the extent of this difference and
its significance in relation to grazing use. Possible deficiencies in the herbaceous
forage may be offset to a large degree by the abundance of browse feed.
28
Forest Species
•
The information regarding the chemical composition of the native forages of
forest areas is much less complete than that available for grassland ranges. Most
of the data are from the analysis of samples collected in areas of predominantly
coniferous forest in the Cypress Hills and Rocky Mountain Foothills. Few-
samples have been obtained from deciduous forest ranges, and no study has been
made of possible differences in composition of species growing in the two forest
types. A summary of the available data is presented in Table 15.
TABLE 15.— CHEMICAL COMPOSITION OF COMMON FORAGE SPECIES OF
FOREST ZONES
Species
Growth
Stage
Av. Date
Collected
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phos-
phorus
Pinegrass
(Calamagrostis rubescens ) .
<( a
Purple oatgrass
( Schizachne purpurascens )
Fringed brome
(Brome ciliatus)
Canada brome
(Bromus purgans)
Smooth aster
(Aster laevis)
Veiny peavine
(Lathyrus venosus)
American vetch
(Vicia americana )
Willows
(Salix spp.)
Aspen poplar
(Populus tremuloides)
Saskatoon bush
( Amelanchier alnifolia). . . .
Leaf.
Flower..
Medium
seed.
Flower
Flower
Flower
Leaf. . .
Leaf . . .
Flower
Leaf.. .
Leaf . . .
Leaf . . .
July 2
Aug. 5
Aug.
15
2
June
22
2
July
3
1
July
4
2
June
22
1
June
18
1
June
29
2
June
14
4
July
3
2
July
14
2
22
40
54
79
92
30
30
50
96
93
23
90
31-80
36-80
35-67
34-18
34-97
36 00
12-78
27-94
29-53
15-84
17-36
21-29
12-
8-
14-
10-
10-
8
11
7-
8-
7-
6-
7-
•13
•14
0-
0-
•53
0-
•69
0-
•69
0-
•97
0-
•63
0-
•54
0-
•50
1-
•39
1-
•84
1-
•28
0-
333
270
410
200
400
330
110
998
428
170
090
990
0-254
0-240
0-160
0-210
0-300
0-267
0-420
0-410
0-211
0-415
0-370
0-350
Pinegrass, the principal forage species of the coniferous forest areas, is
relatively low in protein and high in crude fibre, particularly when in the leaf
stage. The composition of purple oatgrass and the two bromes resembles more
nearly that of the common prairie grasses, and all three are rich in phosphorus.
Data on percentage of nitrogen-free and ether extract were not obtained for most
of the forest grasses.
The data for broad-leaved forage species indicate that they are well
supplied with nutrient elements, being generally higher in percentage of protein
and minerals and lower in fibre content than the grasses. The two legumes,
American vetch and veiny peavine are particularly high in protein content, while
the latter species together with smooth aster and willow is outstanding in
percentage of phosphorus. Data for fat content, obtained for a few of the broad-
leaved plants but not included in Table 15, indicate that these species are as well
supplied with this element as are most prairie grasses. The percentage of
nitrogen-free extract is higher than in grasses of either prairie or forest.
The data in Table 15 are not sufficient to throw much light on the changes
in chemical composition undergone by these forest species during seasonal growth
development. It would appear that the changes are somewhat similar to those
taking place in Submontane Prairie species and less marked than in plants of the
drier prairie zones.
29
Meadow Species
Scattered throughout the zones discussed previously are low-lying areas such
as meadows, sloughs and swamps where soil moisture is abundant. The vegeta-
tion of these areas is affected primarily by the local soil moisture condition and
is much less influenced by climatic factors than is the plant cover of the uplands.
For this reason, certain species such as slough grass, awned sedge and Baltic rush
occur commonly in low areas throughout southern Saskatchewan and Alberta.
Hence, the lowland species of this whole region are treated here as a separate
group. These meadow plants are of great importance in relation to livestock
production, since they constitute the bulk of the native hay harvested in the area,
as well as supplying considerable grazing. The data for meadow grasses are
presented in Table 16.
TABLE 16.— CHEMICAL COMPOSITION OF PRINCIPAL MEADOW GRASSES IN SOUTHERN
SASKATCHEWAN AND ALBERTA
Species
Growth
Stage
Av. Date
Collected
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phos-
phorus
Slough grass
(Beckmannia Syzigachne ) . .
Tufted hairgrass
(Deschompsia caespitosa).
a <<
H It
Tall mannagrass
(Glycerin grandis)
tt tt
tt tt
Marsh reedgrass
(Calamagrostis canadensis )
'< «
tt tt
Northern reedgrass
(Calamagrostis inexpansa ) .
Peed canary grass
(Phalaris arundinacea)
Spangle top
(Fluminca festucacea )
Flower
Medium
seed ....
Leaf
Flower
Medium
seed ....
Leaf
Flower
Seed shed
Leaf
Flower
Seed
Leaf
Flower
Flower... .
Leaf
Flower... .
June 27
Aug. 9
May 22
June 29
July 24
June 16
July 13
Aug. 3
June 16
July 17
Aug. 12
June 2
Aug. 10
July 26
June 22
July 18
9-25
500
17-58
8-40
6-65
21-85
8-50
6-40
12-35
8-26
6-70
18-80
7-10
9-77
12-90
8-00
32
35
31
35
37
22
32
29
30
36
34
27
34
38
27
32
70
11
62
29
36
72
01
67
76
68
20
30
43
52
10
40
7-46
12 00
8-48
9-28
8-81
12-30
8-45
10-77
7-52
6-91
6-93
10-70
11-02
8-91
8-28
7-45
0-240
0-300
0-470
0-260
0-310
0-435
0-370
0-404
0-325
0-345
0-354
0-380
0-480
0-300
0-330
0-210
0-180
0-150
0-228
0-205
0-200
0-370
0-253
0-162
0-148
0141
0-104
0-200
0-155
0-300
0-220
0-120
It is evident that most of these plants are fairly well supplied with nutrient
elements. The protein content is a little lower and the percentage of fibre higher
than in the main shortgrass species (Table 6), but the phosphorus content
averages about the same. Slough grass, tufted hairgrass, tall mannagrass and
reed canary grass are somewhat superior to the reed grasses and spangle top in
percentage of the more desirable constituents.
The changes in composition occurring with seasonal growth development
appear to be similar in general to those found in upland species. However, in
tall mannagrass and marsh reedgrass the fibre content apparently decreases from
the flowering to the seed or seed shed stages. The reason for this deviation from
the normal trend is not evident.
Xon-grasses, chiefly sedges and related forms, constitute a large proportion
of the lowland vegetation in most areas. Analytical data for this group are
presented in Table 17.
30
TABLE 17.— CHEMICAL COMPOSITION OF SEDGES AND RUSHES IN SOUTHERN
SASKATCHEWAN AND ALBERTA
Species
Growth
Stage
Av. Date
Collected
No. of
Samples
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phos-
phorus
Water sedge
(Car ex aquatalis)
<< «
tt '<
Awned sedge
(Car ex atherodes)
U it
a it
Spike rush
( Eleocharis palustris ) .
a it
a it
Baltic rush
(Juncus ater)
<« <<
it it
Three-square bulrush
(Scirpus americanus ) .
Leaf
Flower..
Medium
seed . .
Leaf
Flower..
Medium
seed . .
Leaf
Flower..
Medium
seed . .
Leaf
Flower..
Medium
seed . .
Medium
seed . .
June 28
July 11
July 31
June 12
July 5
July 26
May 24
June 7
June 21
May 26
June 23
Aug. 4
Aug. 3
22
ie
n
15
12
82
20
60
27
16
10;18
9-18
907
24-50
27 03
28-52
26-98
27-33
28-60
20-40
23-21
27-52
27-00
28-68
29-44
29-96
7-64
8-92
8-30
7-77
7-52
8-03
11-46
6-90
9-98
8-23
5-62
5-14
7-90
0-427
0-320
0-570
0-448
0-460
0-599
0-545
0-405
1-300
0-377
0-326
0-363
0-416
0-340
0-207
0-147
0-250
0-160
0-163
0-405
0-230
0-220
0-213
0-149
0-120
0-149
It is evident that the species of Table 17 compare favourably with the
meadow grasses, being generally higher in protein and phosphorus and lower in
crude fibre than the latter. In the flowering stage particularly, the sedges and
Figure 5. — Good growth in a native meadow. The stand consists mainly of tall mannagrass
and coarse sedges. Such vegetation produces hay of fair quality if cut early.
31
rushes appear superior not only to the lowland grasses but also to most upland
species (see Tables 6, 11). Data for ether extract, obtained for a few samples
but not shown in Table 17 indicate that the sedges are low in this constituent.
The percentage of fat varies from one to two per cent in the leaf stage and
declines with growth development.
Data for silica content, not shown in Tables 16 and 17, indicate that most of
the meadow species contain about the same percentage of this element as do the
principal upland grasses. Tall mannagrass and Baltic rush are a little higher
in silica, averaging nearly five per cent in the flowering stage, although the
amount varies considerably in different samples. Gordon and Sampson (19)
found spike rush to be very high in silica, but such was not the case in the
present study.
The data in Table 16 do not give a full picture of changes in composition
with growth development, particularly since no analyses of cured forage were
made. The seed stage in most of the meadow plants occurs in late July or early
August, while the foliage is still green. Analyses of native hay samples, cut at
different growth stages and dates, indicate that the drop in desirable constituents
is very rapid in most meadow species once curing begins. Data on this point
are presented in Table 18.
TABLE 18.— CHEMICAL COMPOSITION OF NATIVE MEADOW HAY CUT IN VARIOUS
GROWTH STAGES
No. of
Samples
Date
Cut
Chemical Composition in Per Cent
Growth Stage
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
Cal-
cium
Phos-
phorus
Leaf
2
2
2
2
June 22
Mid-Aug
Early
Sept. . . .
Oct. 10
15-61
9-50
8-70
6-14
24-32
29-40
32-54
31-94
1-54
0-95
0-83
0-95
51.53
52-20
50-81
54-31
7-00
8-06
6-84
6-66
0-435
0-390
0-340
0-520
0-225
Late seed
0-120
Seed shed, 20% cured . . .
50% Cured
0-110
0-085
This hay consisted mainly of awned sedge, together with lesser amounts of
spangle top, reed grasses, etc. All samples were from the same site. It will be
noted that the percentage of ether extract and phosphorus declined sharply once
the seed stage was reached, and reached a very low point by the time the forage
was half cured. Protein declined also to a considerable extent. These data are
important in connection with the quality of native meadow hay, which is often
poor, due to being cut at a late stage of growth.
Cultivated Species
There are a few cultivated grasses which warrant mention because of their
use in reseeding abandoned fields and depleted native pastures. The most
important member of this group at present is crested wheatgrass, which is being
used extensively for reseeding purposes. This species is well adapted to the
conditions existing in the Shortgrass and Mixed Prairie areas, and appears to
have become established as a permanent constituent of grazing lands in these
regions. Common bromegrass is suited to the Submontane and Parkland zone
and to favoured areas in the Mixed Prairie area. Slender wheatgrass ("western
rye") is valuable chiefly for its tolerance of alkaline conditions. Neither of the
latter two species has been used for reseeding on nearly so large a scale as crested
wheatgrass.
Samples of all three grasses were obtained from dryland plots at the Many-
berries Station while several collections of crested wheatgrass were made in
reseeded fields in the vicinity of Swift Current. The data are presented in
Table 19.
32
TABLE 19.— CHEMICAL COMPOSITION OE IMPORTANT CULTIVATED GRASSES IN
SOUTHERN SASKATCHEWAN AND ALBERTA
No. of
Samples
Av. Date
of
Collection
Chemical Composition in Per Cent
Species and Stage
9
Crude
Protein
Crude
Fibre
Ether
Extract
Nitro-
gen-
free
Extract
Total
Ash
Cal-
cium
Phos-
phorus
Crested wheatgrass
( Agropijron cristatum ) —
Leaf
Emerging from sheath
Flower
8
3
8
8
5
3
3
1
2
3
May 10
June 8
June 29
July 30
Oct. 21
May 12
July 15
Sept. 29
Mav 12
July 10
22-70
13-85
11-66
8-54
4-45
26-90
13 10
710
25 00
11-45
19-94
29-20
33 07
32-53
34-72
18-13
30-56
34-97
20-10
33-80
2-69
1-60
1-81
1-91
1-86
45-83
48 00
46-34
51 10
52 12
8-85
7-45
712
5-92
6-85
0-417
0-285
0-318
0-327
0-300
0-450
0-335
0-260
0-355
0-330
0-274
0-240
0 187
Medium seed
Cured
Common bromc grass
( Bromus inermis )—
Leaf .*
0 144
0051
0-220
I lower
7-78
0 170
Cured
0-060
Slender wheatgrass
( Agropyron
traehycauliim ) —
Leaf
0-250
Flower
7-84
0 170
All three species are well supplied with nutrient elements and tend to be
somewhat superior to most native grasses in this regard. Crested wheatgrass
is higher in protein and phosphorus" content than the average for shortgrass
dominants (Table 6) in all but the cured stage. The percentage of crude fibre,
nitrogen-free extract and total ash is much the same as in the grasses of Table 6,
while the content of ether extract is slightly lower.
■
Fioi BE 6. Abandoned field in the Shortgrass Prairie area, reseeded to crested wheatgrass.
This grass controls weed growth and yields about three times as much forage as
docs the native sod in this zone.
33
Common brome and slender wheat-grass are both slightly higher in protein
and lower in phosphorus than crested wheatgrass. The phosphorus content of
the bromegrass samples appears abnormally low. Sotola (41) in Washington,
found the phosphorus content to be 0-320 per cent in the leaf stage and 0-200
per cent in flower for this species, while Morrison (32) gives a figure of 0-320
per cent for phosphorus in brome hay. Brome did not thrive on the dryland
plots at Manyberries, and this condition may have affected the phosphorus
content. The fact that the same species on irrigated plots at this Station had a
phosphorus content of 0-230 per cent in the flowering stage lends support to the
view that lack of moisture was responsible for the low content of this element in
the dryland material.
DISCUSSION OF RESULTS
Analytical results have been presented for approximately 75 species including
the principal forages of five major vegetation types as well as native meadow
plants and certain cultivated grasses. Points arising from these data will be
discussed under the following headings: —
1. Variability of the data.
2. Correlation between chemical constituents.
3. Differences in composition between species and stages of development.
4. Changes in chemical composition with growth development.
5. The leaf-stem ratio in relation to chemical composition.
Variability of the Data
The study reported in this publication was conducted to determine the
chemical composition of a large number of native forage species in a variety of
range types. For the main forage species of the Shortgrass Prairie zone,
sampling was done in such a manner as to permit statistical treatment of the
results. Samples of these plants were collected annually from the same sites
in each of several growth stages for a number of years. Thus variability due to
differences in site and soil type was controlled to a great extent, although the
effects of variations in climate from year to year were not eliminated.
The data for variability of the results for certain species are presented in
Table 20.
TABLE 20.— VARIABILITY OF DATA FOR CHEMICAL COMPOSITION OF PRINCIPAL
NATIVE FORAGE SPECIES OF THE SHORTGRASS PRAIRIE ZONE
No. of
Samples
Variability in Pe
■ Cent1
Species and Stajre
Crude
Protein
Crude
Fibre
Total
Ash
Calcium
Phos-
phorus
Common speargrass
(Stipa comata)—
Leaf
8
8
6
7
3-0
50
8-3
110
4-9
5-5
9-7
120
3-7
2-7
2-7
50
5-5
2-0
3-8
3-4
4-6
8-4
5-7
8-8
8-1
7-6
()••()
8-0
6-4
8-1
9-7
9-3
9-9.
8-3
9-9
8-8
30
Flower
7-0
Seed
Cured
90
Av. for 4 species2 —
Leaf
5 • 2
Flower
5-7
Medium seed
8 »
Cured
11-2
1 Standard Error (s-) expressed in per cent of the mean for each variable
: Western wheatgrass, grama grass, Junegrass and common speargrass.
34
The data indicate that where six to eight samples were obtained, the sampling
error was below 10 per cent of the mean for most constituents. Such a degree of
variability cannot be considered unduly high in material of this type.
The various chemical constituents differed considerably in variability.
Crude fibre content was generally least, and the percentage of calcium most
variable. There were marked differences among growth stages in this regard.
For example, protein and phosphorus were more variable in the seed and cured
stages than in the leaf or flowering stages.
There were no marked differences in variability among the species of Table
20. Results for other important forage species of the Shortgrass Prairie such as
crested wheatgrass, salt sage and winter fat were found to vary to much the
same extent. In all cases crude fibre was the least variable constituent, while
the variability of most components was least in the leaf and flowering stages.
Few studies have been made of the variability of data from chemical
analyses of range forages. Stoddart (43) in a recent investigation with a single
species (roundleaf snowberry), in Utah found time of collection, soil type and
nature of site to be the principal factors affecting chemical composition. The
variability of crude fibre proved to be higher than that of protein, phosphorus
or calcium. These latter results are not in accord with the findings of the present
study, but the discrepancy may be due to the difference in material used. Data
presented by Kik (26) for samples of little bluestem in Arkansas show less
variability for crude fibre than for any other constituent except total ash.
Results of the present study indicate that the leaf and flowering stages
generally are most suitable for comparative studies of the chemical composition
of prairie forages since the variability of most constituents is at a minimum. The
flowering stage has the additional advantage of being one which lasts for a
relatively short and definite period in most species.
Correlation Among Chemical Constituents
In order to determine the degree of association among the various con-
stituents, correlation coefficients were calculated in certain cases. The most
suitable results for this purpose were those for the forages of the Shortgrass zone
along with a few major species in other zones.
Correlation data for the five major grasses of the Shortgrass Prairie in
several growth stages are presented in Table 21.
TABLE 21.— CORRELATION OF CHEMICAL CONSTITUENTS IN FIVE MAIN GRASSES
OF SHORTGRASS PRAIRIE
Constituents Compared
Crude protein and phosphorus
" crude fibre
" nitrogen-free extract
Crude fibre and phosphorus
Nitrogen-free extract and phosphorus. .
No. of
Samples
32
32
25
32
25
Value
of r
+ 0-93
- 0-86
- 0-75
- 0-77
- 0-67
Value of
rat 1%
Point
0-449
0-449
0-505
0-449
0-505
Significance
High
Data include all stages from leaf to "after winter exposure".
The data indicate a strong positive association between protein and phos-
phorus, with each of these constituents correlated negatively with fibre and
nitrogen-free extract. No significant relationship was found among any other
of the constituents. Calculations made for crested wheatgrass gave correlations
similar to those shown in Table 21.
The above relationships are in accord with the seasonal trend of constituents
in these grasses. Protein and phosphorus decrease greatly with growth develop-
ment, while crude fibre and nitrogen-free extract increase.
35
Correlations for 30 grasses and sedges of major forage importance in the
prairie zones (sandhills included) are presented in Table 22. The data are for
two or more of the leaf, flowering, seed and cured stages for each species.
TABLE 22.— CORRELATION OF CHEMICAL CONSTITUENTS IN MAIN GRASSES OF ALL
PRAIRIE ZONES
Constituents Compared
No. of
Samples
Value
of r
Significance
Crude protein and phosphorus
" crude fibre.
" fibre and phosphorus. . .
Phosphorus and total ash
Calcium and phosphorus
77
77
77
77
77
+0-79
-0-73
-0-51,
+0-11
+0-18.
High
None
Value of r at the 1 per cent point =0-314.
It will be noted that the positive correlation between protein and phosphorus
and the negative association between each of these constituents and crude fibre
is as strong as for the species of Table 21. There is no correlation between
phosphorus and either calcium or total ash.
Possible associations for other constituents such as nitrogen-free extract-
were not calculated due to lack of the necessary data for some species. For the
same reason no attempt was made to determine correlations among constituents
of the broad-leaved forages.
It would appear that, considering all growth stages, there is a high degree
of association among protein, crude fibre and phosphorus in the main grasses and
sedges of the prairie zones. Nitrogen-free extract is correlated with each of the
above components in the major short-grass prairie species, and the same relation-
ship may hold for the grasses of all zones. There is no indication of correlation
between any of the above components and calcium or total ash.
A positive correlation between protein and phosphorus in pasture herbage
has been reported by Daniel (13) in Oklahoma, Greaves (20) in Utah and
numerous workers in more humid pasture regions.
Greaves found other correlations including a positive one between calcium
and total ash and negative associations between protein and fibre, phosphorus
and fibre, phosphorus and calcium, phosphorus and total ash and between fibre
and nitrogen-free extract. This study was made with cured samples of both
grasses and broad-leaved forage species. Greaves concluded that phosphorus
content was a good indication of the nutritive value of the plants used in this
experiment, since protein and crude fat varied directly with phosphorus content
while crude fibre varied inversely.
Comparison of the data obtained in the present study with those of the
workers mentioned above indicates that a positive relationship between protein
and phosphorus is of general occurrence in pasture forages. A negative correla-
tion between each of the above constituents and crude fibre may be common
also. Certain other relationships, such as those of phosphorus with calcium and
total ash, and of nitrogen-free extract with protein and phosphorus, appear to
vary with the material studied.
Differences Among Species and Growth Stages
The data presented previously indicate the existence of differences in the
composition of various forages and particularly in different growth stages of
the same species. A statistical analysis was made of some of the data in order
to determine the extent of these differences. Results for Shortgrass Prairie
species were used to a large extent, since the data for other zones were less
complete.
36
Analysis of variance applied to data for the five main grasses of the Short-
grass area showed no significant difference among species in protein and
phosphorus, the F value falling well below significance in each case. With crude
fibre the F value was significant and the minimum significant difference was
1-95 per cent. The crude fibre content of grama grass was thus significantly
lower than that of the other four species.
Data for differences between growth stages are presented in Table 23.
TABLE 23.— DIFFERENCES IN AVERAGE CHEMICAL COMPOSITION OF THE FIVE MAIN
GRASSES OF THE SHORTGRASS PRAIRIE IN VARIOUS GROWTH STAGES
•
Chemical Composition in Per Cent
Growth Stage
Crude
Protein
Crude
Fibre
Phosphorus
Leaf
18-14
13-10
9-74
7-18
5-02
3-96
25-0
28-6
32-8
33-5
34-5
35-1
0-255
Sheath
0-210
Flower ! .
0-183
Medium seed
0-130
Cured .'
0-085
After winter
0 062
Minimum significant difference between stages
1-75
2 10
0 035
It will be noted that differences in protein content between any two stages
are significant in all but the cured and ''after winter" samples. The crude fibre
content differs significantly between leaf and sheath and between these and all
later stages. The phosphorus content differs significantly between most stages
of development.
A similar statistical analysis was made for 25 major grass and sedge species
of the prairie region, including Shortgrass, Mixed and Submontane Prairie as
well as sandhill areas and native meadows. Comparative data for this number
of species were available for the leaf, flower and seed stages only. While
analyses in other stages, especially the cured forage would have strengthened
the comparison, the three stages used are considered to be representative.
Analysis of variance revealed significant differences between both species and
stages.
The data for differences in composition in various growth stages are
presented in Table 24.
TABLE 24.— DIFFERENCES IN AVERAGE CHEMICAL COMPOSITION OF TWENTY-FIVE
IMPORTANT FORAGE SPECIES IN SOUTHERN ALBERTA AND SASKATCHEWAN
IN VARIOUS GROWTH STAGES
Chemical Composition in Per Cent
Growth Stage
Crude
Protein
Crude
Fibre
Phosphorus
Leaf '
18-1
12-1
9-5
24-3
29-5
30-4
0-269
Flower
0-200
Medium seed
0-165
Minimum significant difference1
3-26
41
0-064
JThe variability of this material, representing species of very different nature growing under widely
differing climatic and soil conditions, was much greater than for that of Table 23.
The percentage of all three constituents in the leaf stage is significantly
higher than in material in the flower and seed stages, but there are no significant
differences between the latter two stages.
37
Data for differences among species may be summarized as follows: —
Protein. — There are few significant differences among the principal grasses
of the prairie zones. Certain species, including green speargrass and crested
wheatgrass (early growth stages only) are above average in protein, being
significantly superior to grama grass, sandgrass, rough fescue and wild oatgrass
in this regard. The broad-leaved forage species included in the study are all
significantly higher in protein than the principal grasses.
Fibre. — Most of the principal grasses of the prairie zones do not differ
significantly among themselves. A few species, including sandgrass, wild oat-
grass and marsh reedgrass are significantly higher in fibre than are the principal
grasses. The majority of the broad-leaved forages are significantly lower in fibre
than any of the grasses studied.
Phosphorus. — Although the main prairie grasses vary considerably in content
of this element, there are few significant differences among species. A few
plants, including saltgrass, wild oatgrass and marsh reedgrass are significantly
lower in phosphorus than the principal grasses. Most of the broad-leaved
forage species are significantly superior to the grasses in phosphorus content.
The principal grasses of the prairie zones appear to be reasonably similar
in content of protein, fibre, phosphorus and other constituents. The correlation
between protein, fibre and phosphorus is illustrated by the fact that species
low in protein usually are high in fibre and poor in phosphorus content. Most
of the broad-leaved forage species are significantly higher in protein and
phosphorus and lower in fibre than the grasses.
Changes in Chemical Composition with Growth Development
It has been shown in the preceding section that statistically significant
changes in chemical composition occur in the shortgrass prairie grasses during
growth development. Similar trends are evident in the data for other grasses,
sedges, forbs and shrubs from all the major zones.
These changes may be summarized as follows: —
(1) Crude protein is at a maximum in the early leaf stage and declines
greatly as growth development proceeds. The minimum content is
reached in the cured forage which has been exposed throughout the
winter.
(2) The percentage of crude fibre varies in an opposite manner to protein,
being lowest in the leaf stage and highest after winter exposure.
(3) The content of ether extract declines irregularly from a maximum in
the early growth stages to a minimum in the cured forage after winter
exposure.
(4) The percentage of nitrogen-free extract increases gradually from the
leaf to the cured stage but decreases slightly with winter exposure.
(5) Total ash content in grasses follows a curvilinear trend, with maxima
in the leaf and cured stages and the minimum' near the flowering stage.
The percentage of silica-free ash actually declines throughout growth
development. The trend for total ash is due to fluctuations in the
silica content. In many broad-leaved forages the ash content is higher
and the percentage of silica lower than in the grasses, so that the
downward seasonal trend shows even in the figures for total ash.
(6) The calcium content of several grasses of the Shortgrass zone exhibits
a curvilinear trend similar to that for total ash. In many other grasses
and broad-leaved species no definite seasonal trend is apparent.
(7) The percentage of phosphorus declines throughout growth development
in a manner similar to protein.
38
The seasonal trends in the various constituents are illustrated in Figures
7, 8, 9 and 10.
22.5
2C.0
17.5
15.0
a 12.5
LO.O
7.5
5.0
2.5
— % 1
x ^
x ^
x ^
X- 15
x ^
x ^
X. , x
X. ^
Xj ^
X. s
X—, v
^^ ^
^^ ^
.270
.240
.210
.180 W
,150
,120
,090 £
,060
.030
LEAF
EMERGING
FLOWER
MEDIUM SEED
CURED AFTER WINTER
EXPOSURE
Figure 7. — Seasonal trend in percentage of crude protein (solid line) and phosphorus (broken line) in five
principal grasses of the Shortgrass Prairie.
t.
11.0
LO.O
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
\ ^VJ ' ^~~*
^ ,^:
V _^
.530
.490
.450
.410
.370
.330 £
.290
,250
.210
.170
LEi*F EMERGING FLO'.VER ' MEDIUM SEED CURED AFTER WINTER
EXPOSURE
Figure 8. — Seasonal trend in percentage of total ash (solid line) and calcium (broken line) in five principal
grasses of the Shortgrass Prairie.
39
54.0
51.0
48.0
45.0
m 43.0
CO
o
o
fe 39.0
O N
a
g 36.0
o
33.0
30.0
27.0
24.0
^ .
S ,
-^
_ /L
S
LEAF
EMERGING
FLOWER
MEDIUM SEED
CURED
AFTER WINTER
EXPOSURE r
Figure 9.— Seasonal trend in percentage of nitrogen-free extract (solid line) and crude fibre (broken line) in
five principal grasses of the Shortgrass Prairie.
25.0
22.5
20.0
17.5
15.0
12.5
10.0
7.5
5.0
2.5
\ "v
-.^.^
\ \
\ \
\ \
• ^
ST^V^
\
^\*<
LEAF EMERGING FLOWER MEDIUM SEED CURED
Figure 10.— Seasonal trend in crude protein content of crested wheatgrass (solid line), in five principal grasses
of Shortgrass Prairie (broken line) and average for winter fat and salt sage (broken and dotted line).
40
The data for seasonal changes in protein, phosphorus, crude fibre and
nitrogen-free extract are in agreement with the findings of other investigators.
It is accepted generally that the percentage of the first two constituents decreases
while that of the latter two increases in growth development.
The irregular but generally downward trend for ether extract found in these
studies is in accord with the findings of other workers. The extreme variability
in data for this constituent is apparent in the results of most investigators, and
has been shown statistically by Stoddart (43).
Comparison of the data for ash is complicated by the fact that few workers
appear to have made determinations of silica-free ash. A high content of silica,
present in most grasses and grass-like species, as well as in many forbs, may mask
seasonal trends in other ^ash elements as has been shown in the present study.
Gordon and Sampson (id) working with California range species, found a down-
ward seasonal trend in silica-free ash. Lack of any definite trend in total ash
has been reported by several workers (25, 42). McCall (30) found a seasonal
increase in total ash for bluebunch fescue, but notes that the silica content was
high.
Several investigators (19, 42) have commented on the discrepancies in the
results reported for trends of calcium in pasture species. Seasonal increases,
decreases and lack of any definite trend have all been reported. The curvilinear
trend found in some grasses (Tables 5, 6) in the present study appears to be
somewhat different from anything reported to date. However, the data indicate
that this trend is not followed closely by all grasses, even in the Shortgrass
Prairie group, and there is no evidence that it is of general occurrence in other
zones and plant groups.
The Leaf-stem Ratio in Relation to Chemical Composition
The relative effects of leaf and stem production in grasses were studied by
means of (1) separate analyses of foliage and culms from samples of a few
major species of the Shortgrass zone and (2) analyses of plants which remained
in the leaf stage throughout the season.
The data on leaf and culm samples are presented in Table 25.
TABLE 25.— CHEMICAL COMPOSITION OF LEAFAGE AND CULMS IN SOME PRAIRIE
GRASSES
Species and Material
No. of
Samples
Av. Date
Collected
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phos-
phorus
Junegrass
(Koeleria cristatu )
Cured, leaf only. . .
Cured, culms only
Common speargrass
(Stipa comata)
Cured, leaf only. . .
Cured, culms only
Grama grass
f Bouteloua gracilis)
Cured, leaf only. . .
Cured, culms only
Oct.
Oct.
40
Sept. 27
Sept. 27
Oct. 4
Oct. 4
6-94
3-78
7-75
5-30
30-46
33-94
28-75
33-94
25-57
32-03
11-51
6 08
7-19
4-76
9-84
6-71
0-540
0-237
0-525
0-201
0-473
0-261
0-100
0-057
0-135
0 057
0-112
0-108
In each species there are marked differences in chemical composition
between the leaf and culm material. The leafage generally is richer in protein,
total ash, calcium and phosphorus, and lower in percentage of crude fibre. In
grama grass the culms are unusually high in phosphorus content, nearly equalling
the leaves in this regard. Separate analyses of leaf and culm were not made in
early growth stage, but it seems likely that differences in chemical composition
between foliage and stems occur throughout growth development.
41
The data for the composition of grass foliage at different times during the
season along with comparative data for material in the flowering stage are
presented in Table 26.
TABLE 26.— THE CHEMICAL COMPOSITION OF CERTAIN PRAIRIE GRASSES IN LEAF
AT DIFFERENT TIMES DURING THE YEAR AND IN THE FLOWERING STAGE
Species and Stage
No. of
Samples
Av. Date
Collected
Chemical Composition in Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Cal-
cium
Phos-
phorus
Western wheatgrass
(Agropyron Smithii)
Medium leaf
8
4
9
3
2
2
3
3
2
Mav 27
July 4
July 3
May 30
June 23
Oct. 18
June 16
July 21
June 26
17-80
12-95
10 00
16-06
11-82
4-16
12-00
8-83
8-58
27-84
32-50
33-50
26-65
33-48
36-66
30-26
31-75
33-15
8-36
8-17
7-40
6-80
6-55
9-49
10-14
10-06
11-42
0-372
0-402
0-285
0-300
0-350
0-540
0-300
0-295
0 185
0-219
Late leaf
0-191
Flower
Northern wheatgrass
(Agropyron dasystachyum)
Leaf
0-156
0-210
Late leaf
0-160
Leaf, cured
0-070
Rough fescue
(Festuca scabrella)
Medium leaf
0-182
Late leaf
0-129
Flower
0-180
The three species in Table 26 are from Shortgrass, Mixed and Submontane
Prairie respectively. It is evident that marked changes occur in the composition
of the foliage of all three species as the season progresses, even when no culm
production takes place. The changes are similar to those occurring in normal
growth development. Crude protein and phosphorus decrease while crude fibre
increases.
Comparison of material in flower with that in leaf at approximately the
same date indicates that both the development of culms and increasing maturity
of the foliage are concerned in the seasonal variation in chemical composition.
The results outlined above are in general agreement with those of other
workers. It has been found that the chemical composition of grass foliage
changes greatly during the season, while the development of culms affects
composition to a marked extent.
The data obtained in the present study indicate that grass which remains
in the leaf stage throughout the season has a more desirable chemical composition
than when culm formation occurs. However, the lower yields of the former are
likely to offset this advantage to a large extent in the drier grassland zones at
least.
EFFECTS OF CERTAIN FACTORS ON CHEMICAL COMPOSITION
OF NATIVE FORAGES
Effects of Climate
Sampling of the principal native forages at the Manyberries Station during
the period 1929 to 1938 afforded an opportunity for study of the effects of
variations in climate on chemical composition. Samples of each of the main
species were collected at the same sites and in similar growth stages each year
during most of this period.
Under the dry conditions prevailing in the Manyberries area, plant growth
is limited mainly by the supply of available moisture, as shown by the close
relationship between precipitation, evaporation and native forage yields (8).
Pertinent climatic data for the period are presented in Table 27.
42
TABLE 27.— PRECIPITATION AND EVAPORATION IN INCHES AT THE MANYBERRIES
RANGE STATION, 1929-1938
Year
Precipitation
Evapor-
ation
P/E Ratio1
Category-
Total
Apr. -Sept.
May-Sept.
1929
9-96
13-40
10-20
12-40
11-20
11-20
8-41
7-19
10-30
12-70
6-50
8-40
7-29
10-45
8-52
6-90
5-43
4-25
5-82
9-00
32-99
33-76
33-19
26-56
36-55
33-05
32-87
38-98
30-43
26-77
0-197
0-249
0-220
0-393
0-233
0-209
0-165
0-109
0-191
0-336
Medium dry.
1930
1931
a a
1932. . .
"Favourable".
1933
Medium dry.
U ((
1934
1935
il (I
1936
"Very dry".
1937
Medium dry.
1938
"Favourable".
Av
10-67
7-26
32-52
0-230
1 Ratio of precipitation for Apr.-Sept. to evaporation, May-Sept.
While there was considerable variation in conditions affecting plant growth,
most of the seasons tended to be fairly similar. Only in 1932, 1936 and 1938
was there marked deviation from the group average. To facilitate analysis of
the data, the years have been grouped into three classes as shown in Table 27.
Actually, the whole period was one of comparative drought, and the "medium
dry" years included several seasons such as 1935 and 1937 during which condi-
tions for plant growth were almost as unfavourable as in 1936.
Data for samples of the five major grasses collected at the Many berries
site in the leaf, flower and seed stages are grouped according to the above division
of years. Since few samples were available for 1936, comparison was confined
to the groups of "favourable" and "medium dry" years. The data are summar-
ized in Table 28.
TABLE 28.— EFFECTS OF CLIMATE ON CHEMICAL COMPOSITION OF SHORTGRASS
PRAIRIE GRASSES— 1929-1938 INCLUDED
/
Average Chemical Composition in "Medium Dry'
and "Favourable" Years
Constituent
Leaf Stage
Flower Stage
Seed Stage
Med.
Dry
Favour-
able
DifT.
in P.C.
Med.
Dry
Favour-
able
Diff.
in P.C.
Med.
Dry
Favour-
able
Diff.
in P.C.
Crude protein
Crude fibre
18-8
24-3
8-95
0-402
0-251
18-8
26-3
9-96
0-410
0-278
+ 8-2
+ 11-3
+ 10-8
100
32-4
6-32
0-278
0-176
10-7
35-7
7-18
0-261
0-234
+ 6-8
+ 10-0
+ 13-6
- 6-1
+31-**
7-7
32-7
6-26
0-333
0 130
7-6
34-7
7-24
0-270
0 153
+ 6-0
Total ash
+ 15-6
Calcium
-19-0
Phosphorus
+ 17-7*
* Significant, beyond 5 per cent point.
** Highly significant difference, beyond 1 per cent point.
The only significant differences are those for the increase of phosphorus
content in the flowering and seed samples during the "favourable" years. The
tendency for the percentage of crude fibre and total ash to be higher in the
"favourable" seasons is fairly marked in each growth stage and may represent
a real trend, though not significant statistically in the samples studied.
Culm production was much greater in favourable than in dry years.
According to the data of Table 25 there would be a tendency for the content
of crude fibre to increase and that of protein, total ash and phosphorus to
decrease with an increase in the proportion of culms. Apparently the greater
vigour of growth and delay in curing due to better moisture conditions offset
43
this effect in the case of protein and more than offset it for phosphorus and
possibly total ash.
The literature indicates that the phosphorus content of forage plants usually
is lessened under drought conditions. However, Scott (39) in Montana found no
marked effect of precipitation on either the phosphorus or calcium content of
native forage species. In Oklahoma, Daniel and Harper (15) reported that the
phosphorus content of native grasses was greater in wet years than in dry ones,
while the trend for calcium was just the opposite. A similar trend has been
noted in New Zealand (1) and in Australia (36). The same tendency is evident
in some of the data in the present study, e.g., Table 28, material in the seed
stage.
In pastures of more humid areas, where the grass usually is kept in the leaf
stage, decreases of protein as well as of phosphorus often occur under dry condi-
tions (1, 21). The percentage of protein does not seem to be affected commonly
in this way in the herbage of grazing lands in drier regions.
Effects of Soil
There is wide variation in the soils of the native pasture areas of southern
Alberta and Saskatchewan, four zonal types and a wide range of texture classes
being included. However, many of the major forage species are confined largely
to one soil zone and often to soils of certain textures within -the zone. For
instance, common speargrass is abundant mainly in the Brown and Dark Brown
Soil zones and is confined largely to soils not finer than loams. Thus the occur-
rence of the same species on widely differing soil types is not so common as
might be supposed.
Some study was made of the composition of certain grasses on normal prairie
soils as compared with the same species growing on adjacent sandhill areas.
In this case, climatic conditions were similar at the two sites and the only major
habitat difference was that of soil type. Nine paired samples of grasses were
obtained on such sites. These included samples of each of three species in the
leaf, flowering and cured stages of growth. The results are presented in
Table 29.
TABLE 29.— EFFECT OF SOIL TYPE ON CHEMICAL COMPOSITION OF THREE COMMON
PRAIRIE GRASSES*
Soil Type
Chemical Composition
n Per Cent
Crude
Protein
Crude
Fibre
Total
Ash
Calcium
Phosphorus
Brown loam
Sand
Difference
12-2
11-8
- 0-4
30- 1
29-6
- 0-5
7-04
6-47
-0-57
0-291
0-327
+0-036
0-216
0 162
-0054
Minimum significant difference for phosphorus = 0-050%.
1 Junegrass, common speargrass and northern wheatgrass.
A significant difference in composition of forages on the two soil types
occurred only in the case of phosphorus.
Studies by other workers do not indicate the presence of a simple relation-
ship between the composition of forage plants and the soil upon which they grow.
However, it is apparent that much more study is needed on this problem.
Fraps and Fudge (18) in Texas found correlations between the percentage
of protein, calcium and phosphorus in the soil and in pasture plants. However,
the relationship held only for certain species and some soil types. In Oklahoma,
Daniel and Harper (14) reported a slight correlation between the calcium and
44
phosphorus content of soils and of the native grasses growing on them. However,
these authors stress the complexity of the relationship and conclude that "the
study of a single plant food element in the soil will not give an accurate indica-
tion as to the amount of that element which will be found in the plant."
Another important but less direct effect of soil type on the chemical
composition of pasture herbage is that due to differences in botanical composi-
tion. In sandhill areas, the forage includes both species common to the whole
prairie region and others confined largely to sandy soils. Some of the latter
group, including sandgrass and sand dropseed are inferior in chemical composi-
tion to most species of normal prairie. The crude fibre content is higher and the
percentage of protein, fat and phosphorus is lower than in typical prairie forages.
Effects of Commercial Fertilizers
The effect of several commercial fertilizers on the composition of native
herbage was tested at the Manyberries Experiment Station. Two sites were
used, one on fine sandy loam, the other on a silt loam alluvial soil. The
vegetation of the first site was composed mainly of common speargrass and
grama grass, while western wheatgrass dominated on the second. The fertilizer
was applied as a top dressing in early spring, at an average rate of 150 pounds
per acre. From seven to nine replicates were used for each treatment.
In the fajl, forage samples were collected from each individual plot and
the content of protein, phosphorus and calcium determined. The results are
presented in Table 30.
TABLE 30.— EFFECT OF FERTILIZERS ON CHEMICAL COMPOSITION OF SHORTGRASS
PRAIRIE FORAGE, MANYBERRIES, 1930
Constituent
Site
Composition in Per Cent for Different Treatments
Minimum
Sig. Diff.
Ammonium
Phosphate
Sodium
Nitrate
Ammonium
Sulphate
Super-
phosphate
Unfertilized
Check
Crude protein
Crude protein
Phosphorus
1
2
1
2
7-9
6-0
0-188
0 090
8-2
6-2
0 131
0 070
8-3
6-3
0-148
0 079
6-7
4-9
0-157
0 080
7-1
5-1
0135
0-070
1-2
0-44
0-017
Phosphorus.
0010
There were no significant differences in protein content at site one, although
the increases for ammonium sulphate and sodium nitrate approached significance.
In this connection it should be noted that forage yields were increased signifi-
cantly by all of the nitrogenous fertilizers applied, the increases varying from
32 to 36 per cent. Thus the absolute amount of protein produced on each plot
was increased appreciably even in cases where the percentage in the plants was
not altered significantly. At site two, all three nitrogenous fertilizers raised the
percentage of protein significantly.
The phosphorus content of the forage at each site was increased significantly
by both ammonium phosphate and superphosphate. Ammonium sulphate
increased the percentage of phosphorus also, but not quite to the point of
significance.
Differences in results at the two sites are in keeping with the nature of the
soils. The data given in Table 3, show that both nitrogen and available
phosphorus are present in higher amounts in the sandy loam upland soil than
in the silt loam. This would account probably for the greater response to
nitrogenous fertilizers at site two. With phosphorus, the data do not indicate
any differential response due to differences in the two soils.
The experiment described above was conducted in 1930. Similar results
were obtained with tests made in 1931. However, in 1931, sodium nitrate
increased the protein content of the forage significantly at site one.
45
Climatic 'conditions during 1930 and 1931 were about average for the
Manyberries area (see Table 27). Hence the results of the fertilizer tests may
be considered fairly typical of what might be expected over a longer period.
A few trials of fertilizer application on Submontane Prairie in the Cypress
Hills area yielded striking results. The vegetation in this case consisted mainly
of rough fescue and the soil was a shallow black, gravelly loam.
The results of top dressing with commercial fertilizers at the rate of 150
pounds per acre were as follows: —
(1) The phosphorus content of the forage was increased 140 per cent by
ammonium phosphate and 97 per cent by superphosphate.
(2) Protein content was affected less, being increased 19 per cent by
ammonium phosphate and 18 per cent by ammonium sulphate.
The soil type on which this test was conducted is generally low in available
phosphorus, being inferior to normal soils of the Brown zone in this regard (50).
There are many references in the literature to the effects of commercial
fertilizers on the composition of pasture plants in relatively humid areas.
Generally, applications of nitrogen and phosphorus result in increases in the
percentage of protein and phosphorus in the forage. The effects are most marked
on soils of low fertility.
Fewer studies of this nature have been made with pastures in drier
regions. Richardson and co-workers (36) in Australia obtained increases in the
phosphorus content of native forage plants due to applications of phosphatic
fertilizers on soils deficient in this mineral. Similar results in South Africa
have been reported by Henrici (24). In Montana, Willis and Harrington (48)
tested the application of triple superphosphate to dry land plots of crested
wheatgrass, brome grass and native prairie. Marked increases in the phosphorus
content of the herbage were obtained in all three cases, the response of the
native grasses being greater than that of the cultivated species.
CHEMICAL COMPOSITION IN RELATION TO LIVESTOCK NUTRITION
AND GRAZING PRACTICES
The chemical composition of a large number of native forage species has
been discussed in preceding sections of this publication. In the following portion,
the relation of the composition of these plants to livestock nutrition and
grazing practices in southern Saskatchewan and Alberta will be treated briefly.
Chemical Composition and Nutritive Value
The ultimate use of range forage is as feed for livestock, hence it is
nutritive value rather than chemical composition which is of prime importance.
However, determination of the nutritive value of any feed involves actual tests
with livestock and is too costly and laborious a process to be used on many
species. Thus, it is necessary to rely largely on chemical analyses, together
with the results of such feeding trials as may be made.
The analyses presented in this study were made by the regular ''feeding
stuffs" procedure which has been standard for such Avork. In this method,
nitrogen, ether extract (fats, waxes, etc.), total ash and crude fibre are deter-
mined. The crude protein content is calculated from the percentage of nitrogen
by multiplying the latter by a standard factor (6-25). The difference between
the combined total of crude protein, crude fibre, ether extract and total ash and
one hundred per cent represents the nitrogen-free extract. This fraction cons
of a variety of carbohydrates including starches, sugars and cellulose.
The validity of the division of the carbohydrate fraction into crude fibre
and nitrogen-free extract has been questioned by Maynard (29), Norman (34).
Crampton and co-workers (10, 11) and others. Formerly it was assumed
46
generally that the crude fibre content of any feed was largely indigestible.
Actually it has been shown that the crude fibre content of young grass may be
as digestible as the nitrogen-free extract (10). The latter constituent is itself
a conglomeration of substances, the relative amounts and digestibility of which
may vary greatly during growth development.
Recent studies have shown that lignin is of great importance in connection
with the nutritive value of forages (10, 29). Lignin is low in digestibility, and
its presence affects the digestibility of other constituents, especially cellulose.
Revised procedures for analysis have been suggested in which the carbohydrate
fraction is divided into cellulose, lignin and "other carbohydrates". While such
methods have not yet been perfected, analyses made in this manner by Crampton
and Forshaw (11) in Quebec and Patton and Gieseker (35) in Montana have
yielded results more in accord with the results of actual feeding trials than those
obtained by the regular feeding stuffs analysis.
In view of the above facts, it is evident that the results of chemical
analyses must be interpreted with some caution. Formerly it was assumed that
high feeding value was associated mainly with high protein and low crude fibre
content but it is evident that this assumption cannot be regarded as entirely
valid for immature plants, although it still applies fairly well to cured forages.
In young grass the crude fibre fraction is relatively digestible, and the high
nutritive value may be due as much to the presence of certain carbohydrates as
to high protein content.
The standard chemical analyses do provide a comparative measure for
different forages and serve to show what constituents are deficient or present in
excess. The determination of both phosphorus and calcium content in the
present study added greatly to the value of the analyses.
No digestibility trials have been made with range forages in Western
Canada, but a few such studies have been made in the United States. Most appli-
cable to the present study are the investigations of Christensen and Hopper (9) in
North Dakota, and Sotola (40, 41) and Burkitt (4) in the state of Washington.
Christensen and Hopper fed native prairie hay cut in early April, July and
October to steers. This hay contained a high percentage of common speargrass
(Stipa comata). The October and April cuttings consisted of cured forage, and
the April lot had stood out over winter. It was found that the digestibility of
all constituents was highest in the July cutting and lower in the other two. The
palatability of the July cuttings proved to be higher than that of the April or
October cuttings, and greater amounts of the former were eaten.
Sotola fed samples of crested wheatgrass cut in the early leaf, late leaf and
flowering stages to sheep. The percentage of total digestible nutrients was found
to be similar in the two leaf stages but much lower in the flowering samples.
The percentage of digestible protein and fat declined more rapidly than that of
crude fibre and nitrogen-free extract. A similar experiment using common brome
grass gave comparable results but indicated that brome retains high nutritive
value to a more advanced stage than does crested wheatgrass.
Burkitt tested the feeding value of beardless wheatgrass (Agropyron inerme)
in early leaf, late leaf and flowering stages by a technique similar to that of
Sotola. The results showed that the greatest consumption of feed and best gains
were made by the animals fed on grass in the early leaf stage. The digestibility
of all nutrients decreased with growth development.
The studies mentioned above are of particular importance in the present
case because of the nature of the forages studied. The North Dakota prairie
hay was similar in composition to the forage of Mixed Prairie areas in Western
Canada. Crested wheatgrass, studied by Sotola, has become an important range
species due to its wide use in reseeding abandoned fields and depleted pastures,
while common brome grass is used for the same purpose to a lesser extent.
47
Beardless wheatgrass is not common in the Prairie Provinces but is similar in
chemical composition and growth development to many of the principal prairie
grasses.
All of these digestibility trials agreed in finding that the nutritive value of
range grasses is highest in the leaf stage and declines with growth development,
reaching a minimum value in the cured stage. Christensen and Hopper found
the digestibility of the forage which had stood out over winter to be slightly
higher than that of the October cutting. However, studies made in California
(23) indicate that a further decline in feeding value may occur in cured forage
which stands out over winter. The trend in winter probably depends on climatic
conditions; rainfall and wet snow being the principal leaching agents.
Palatability of Forage in Relation to Livestock Nutrition
It is obvious that palatability is of prime importance in connection with
the grazing value of any species. Desirable chemical composition is of little
value unless a species is eaten readily by livestock.
Studies of the relative palatability of the common species of the Shortgrass
Prairie have been made since 1928. The palatability of species in other range
zones has been investigated in more recent years. Comparative ratings have
been made for the amounts of different species eaten in various growth stages,
at different times of the year and under various intensities of grazing. In the
case of the Shortgrass Prairie species, enough studies have been made to give
a fairly complete picture of the relative palatability of plants in this zone.
Palatability is influenced by a number of factors, including class of livestock,
intensity of grazing, growth stage of the plants, time of year and relative
abundance of other desirable species. It follows that palatability ratings can
be regarded as approximations from which marked deviations undoubtedly will
occur. Data for the Shortgrass Prairie species are presented in Table 31.
TABLE 31.— RELATIVE PALATABILITY TO CATTLE OF PRINCIPAL NATIVE SPECIES OF
SHORTGRASS PRAIRIE
(1)
Eaten Readily
(2)
Eaten Fairly Readily
(3)
Eaten Slightly
(4)
Eaten Rarely or not
at all
Common speargrass
Plains reedgrass
Prairie muhlenbergia.
Wild barley. .
Dwarf everlasting.
Grama grass
Saltgrass
Dwarf phlox.
Western wheatgrass
Alkali cordgrass
Involute-leaved sedge
Pasture sage
Broom weed.
Junegrass
Russian thistle
Cactus (all species).
Dwarf bluegrass
Sagebrush
Little clubmoss.
Niggerwool
Winter fat
Salt sage
Most of the grasses and a few broad-leaved species are eaten readily by
cattle and other classes of live stock. However, there are seasonal differences
among even the favoured species. Grama grass usually is eaten less than spear-
grass or wheatgrass during the spring and summer months, but it is taken readily
in fall and winter. Dwarf bluegrass is eaten mainly in spring while still green
and is grazed very little after the middle of June.
Many of the plants of group two and some in group three are eaten readily
enough at certain times of the year. Saltgrass and alkali cordgrass are grazed
48
well in late fall and winter, but are avoided earlier in the season. Pasture sage
is eaten fairly readily in winter, although rarely touched by cattle in summer.
Sagebrush is grazed considerably in winter. Sheep eat much more of the sages
and of most other broad-leaved species than do cattle. Russian thistle is eaten
readily when green and tender but less when mature and spiny.
While most of the highly palatable species contain high percentages of
desirable nutrients, there are unpalatable plants such as certain native legumes
and broom weed which are rich in desirable constituents also. Even plants
poisonous to livestock may be well supplied with, nutrient elements and may be
eaten on this account. Succulence appears to be an important factor affecting
palatability. It was observed that several of the broad-leaved species, including
salt sage and winter fat, are grazed much more in the fall after the grasses have
cured and when these non-grasses are still comparatively green.
The data obtained for plants in the other zones are less complete than those
for the Shortgrass Prairie. Approximate ratings for the principal species are
presented in Table 32.
TABLE 32.— RELATIVE PALATABILITY TO CATTLE OF PRINCIPAL SPECIES OF OTHER
PRAIRIE ZONES*
(1)
Eaten Readily
(2)
Eaten Fairly Readily
(3)
Eaten Slightly
(4)
Eaten Rarely or not
at all
Short-awned porcupine
grass
Green speargrass
Northern wheatgrass.
Awned wheatgrass. . .
Slender wheatgrass. . ,
Rough fescue
Bromes (all species)..
Indian ricegrass
Sand dropseed
Wild oatgrasses
Willows (most species).
Sandgrass
Goldenrods (most species
Wild lupines
American hedysarum. . . .
Wild licorice
Western snowberry
Chokecherry
Shrubby cinquefoil
Sandbar willow
Aspen poplar
Slender sage.
Prairie goldenrod.
Sandhill rose.
Lance-leaved psoralea .
1 Includes species of Mixed and Submontane Prairie as well as sandhill vegetation.
In general, the grasses of all prairie zones are medium to high in palatability,
while many of the broad-leaved forages are less desirable. Virtually all the
species listed in class two are eaten readily in late fall and winter but to a
lesser extent earlier in the season.
'Information regarding the relative palatability of forest range species is
at present very incomplete and no attempt is made here to rate these plants.
Result.- of studies made to date indicate that most of the grasses and many of
the forbs and shrubs of timber pastures are eaten readily by all classes of
live stock.
Data from feeding trials have indicated the importance of palatability as
a factor affecting the amount of forage consumed and the gains made by live
stock. In the tests by Ohristensen and Hopper and by Burkitt, described in
a previous section, the amounts of the various feeds consumed decreased
significantly in later growth stages. Undoubtedly this smaller intake of feed was
partially responsible for the declines noted in the gains of the test animals.
To what extent the total dry matter intake of animals grazing on the range is
affected by the degree of forage maturity is not known at present.
49
Seasonal Changes in Chemical Composition in Relation to
Gains Made by Livestock
Data presented in previous sections have shown that there is a marked
seasonal decline in the percentage of certain nutrient elements in range forage
plants. In addition, the digestibility of most fractions decreases as growth
development proceeds. The cobined effect is to furnish range livestock with
feed high in digestible protein, carbohydrates and minerals in spring and early
summer. There is a marked decline in feed quality during the remainder of the
year. The reaction of the animals to this seasonal variation in quality of forage
is of great importance to the producer of livestock.
Studies have been made at the Manyberries Range Station (46) of the gains
made by different ages and classes of Hereford cattle on moderately grazed
native pastures. The data for one and two year old steers are presented in
Table 33.
TABLE 33.— AVERAGE GAINS IN WEIGHT OF CATTLE ON SHORTGRASS PRAIRIE
RANGE AT MANYBERRIES, ALBERTA
Gain in Weight in Pounds1
Class of Cattle
April 1-
June 15
June 16-
September 1
September 2-
November 15
Total
Yearling steers i
Two vear old steers
131
145
138
159
46
52
315
356
1 The data are for the 8-year period, 1929 to 1936 inclusive.
Highest gains were made during the months of May, June, July and
August. Gains after the end of September were slight.
The rate of gain is related evidently to the quality of the available forage.
In May, June and July there is plenty of forage in the earlier growth stages,
while even in August some of the later species are more or less green. By
September all forage usually is cured. The fact that higher gains were not
made in April and May appears to be due partly to the condition of the experi-
mental animals at the start of the grazing season. These cattle were wintered
on the range with a minimum of extra feed, and apparently required a few weeks
on high quality forage before starting to make rapid gains. Another factor of
importance in this regard is the lack of an adequate volume of desirable forage
early in the season.
Similar trends for seasonal gains in cattle have been reported from other
western range areas. Sarvis (37) in North Dakota studied the gains of cattle
on native pasture over a twenty-year period. The average gains for two year
old steers on moderately grazed fields were: May — 53, June — 107, July — 69,
August — 56 and September — 38 pounds. In October there was a loss of 3 pounds,
making an average seasonal gain of 320 pounds.
It is evident from the above data that the gains made by livestock on the
range are determined not only by the quantity but also by the quality of the
forage available. High rates of gain cannot be expected from forage of low
nutritive value even though stock may have access to an abundance of it. On
the other hand, large and economical gains can be made during the spring and
summer months provided that adequate supplies of forage and water are avail-
able.
The marked seasonal decline which occurs in the nutritive value of range
forage and in the gains made by livestock grazing on it is of great importance in
regard to the time of marketing, particularly for cattle. Since the rate of gain
after the end of August is very low, there is little advantage in holding beef
50
animals on pasture after that time unless steps are taken to produce added
gains. This may be done either by the supplemental feeding of grain to cattle
on the range, or by moving them onto green forage as found on irrigated pasture
or "cover crops" on grain fields. By means of either of these two practices it is
possible not only to increase the weight of the animals but also to improve their
finish.
The Chemical Composition of Forages in Relation to Grazing Practices
Since the health and proper development of livestock depends to such an
extent on the composition of their feed, it follows that this factor is one to be
considered in range management. This is true particularly because of the great
variations which occur in the chemical composition and nutritive value of
prairie forage during different seasons of the year.
A knowledge of the chemical composition of the main species of an area
can be used to good advantage in planning the best utilization of the forage.
Some points of practical importance in this regard are as follows: —
1. Pastures which are to be grazed early in the spring should not be cropped
closely during the previous fall. The young grass of early spring is not a bal-
anced feed, being more of a watered concentrate. Mixed with cured forage, it
makes excellent feed, while eaten alone it is apt to produce scouring in stock
with consequent poor gains. In addition, when no old growth is available, stock
tend to wander excessively in order to obtain enough bulk. This excessive
travelling is harmful to animals and pasture alike.
2. Pastures containing a mixture of species usually are preferable to those
composed of pure stands of one species. The various native and introduced
pasture forages vary considerably in chemical composition, palatability and
growth development. Hence, a mixed stand usually will produce a more desir-
able type of feed throughout the whole season. For example, in the Shortgrass
Prairie, early species such as Junegrass and niggerwool are valuable especially
for early spring pasture, while speargrass and western wheatgrass are excellent
for late spring and summer. Grama grass, which is later in growth develop-
ment than any of these is of little use for spring grazing but makes good feed
for late summer and fall. Some of the broad-leaved forage plants, such as
winter fat and salt sage remain green for a period in early fall after the grasses
have cured and are eaten extensively at that time. In winter, species such as
pasture sage which are unpalatable during the summer are grazed considerably
and provide valuable nutrients.
3. Where pastures dominated by one species do occur, every effort should
be made to utilize them at the time of year when that species is relatively most
valuable as feed. This problem has arisen in some prairie regions where large
areas of abandoned farm land and depleted native pasture have been seeded to
crested wheatgrass. This species begins growth earlier in the spring than most
native forages and often makes additional green growth in the fall when the
latter are cured. However, it tends to become dormant and less palatable in
mid-summer. It is suited best for spring and fall grazing and should be used
in that manner if possible. Where areas of native pasture are available, a
rotation with the latter used in midsummer gives excellent results.
4. The relative feeding value of different classes of forage is a factor worth
consideration in choosing areas for winter grazing. Many of the broad-leaved
herbs and shrubs are higher in nutritive value when in the cured stage than are
the grasses. In addition, species such as pasture sage and sagebrush which are
relatively unpalatable in the summer are utilized to a considerable extent in
the winter. McCall (31) at Pullman, Washington, found that a mixture of
10 per cent of sagebrush and other non-grasses with 90 per cent of bluebunch
wheatgrass was more palatable, digestible and nutritious for lambs than was
cured grass alone.
51
It follows from the above facts that, other factors being equal, an area
containing a considerable proportion of broad-leaved forages is preferable for
winter pasture to one containing grass only. Fortunately, areas of rough
topography such as are desirable for winter grazing because of the shelter
provided often contain considerable broad-leaved forage. Winterfat, salt sage,
willows, pasture sage and some sagebrush are highly desirable on a winter range.
5. In view of the decline in nutrient content and digestibility of the native
forage as it matures, the question of supplemental winter feeding in the range
areas merits consideration. The data available indicate that digestible protein
and total digestible nutrients as well as phosphorus may be deficient in the cured
range forage. While dry stock may not surfer from such a diet, it is apt to be
inadequate for proper nutrition of cows in calf or ewes carrying lambs. For
such animals, supplemental feeding with hay of good quality or a concentrate
such as grain or oilmeal may be desirable in order to remedy the deficiencies
of the cured grass. The beneficial results obtained by ranchers who are following
this practice indicate the value of supplemental feeding where this can be done
economically.
Figure 11. — Good winter range in the Shortgrass Prairie zone. Plenty of forage, mainly
western wheatgrass with some sagebrush, occurs on the flat, while shelter is
provided by the rougher lands in the background.
Feeding low quality hay to cattle on winter pasture will do little to improve
their nutrition, as such hay is low in the very constituents which are deficient
in cured grass. This is true particularly of native meadow hay cut in a late
growth stage.
Mineral Deficiencies and Supplements
Many minerals, including calcium, phosphorus, sodium, chlorine, magnesium,
potassium and traces of iron, iodine and cobalt are required for the proper
02
nutrition of livestock. Calcium and phosphorus are the constituents required
in greatest amount and apart from the elements contained in common salt are
the two most frequently deficient in the diet of grazing animals.
Numerous studies of the chemical composition of forages have shown that
calcium, while frequently deficient in humid areas, is present usually in sufficient
amounts in the forage of drier regions. Phosphorus, on the other hand, often is
deficient in the feeds of dry areas. A severe phosphorus deficiency has been
found to be widespread in South Africa. In North America, deficiencies have
been reported from Texas, New Mexico, California, Montana and Manitoba
while the forage of several other areas has been found to be low in phosphorus
at certain periods.
Various estimates have been made of the amounts of calcium and phosphorus
needed by grazing animals and hence in the forage upon which they feed.
Watkins (47) concluded from his own studies in New Mexico and from those
of other workers in various parts of the world that 0-250 per cent of calcium and
0-120 per cent of phosphorus is the minimum required by range cattle. The
average phosphorus content of the forage of areas deficient in that mineral was
calculated by Fraps and Fudge (18) to be 0-082 per cent while that of normal
areas was 0-170 per cent. Most investigators recognize a difference between
the amount of phosphorus necessary to prevent obvious deficiency symptoms and
that needed for maximum development of the animal. A further source of
variation in estimating requirements of calcium and phosphorus is that these
vary considerably in different classes and ages of livestock.' Generally, young
animals and pregnant or lactating females have the highest requirements. It is
obvious that no one level of calcium or phosphorus can be set as a minimum
for all classes of livestock. Fraps and Fudge (18) have worked out approximate
standards which are useful as a guide in this regard.
Data presented in the present publication show that the content of calcium
and phosphorus, like that of other constituents, varies considerably in different
growth stages of range forages. Any assessment of the status of these species
with regard to minerals must take into account such seasonal changes. Data
for the calcium and phosphorus content of the five principal grasses of the
Shortgrass Prairie in various growth stages are presented in Table 34. The
rating of each stage according to the Fraps and Fudge standard is shown.
TABLE 34.— CALCIUM AND PHOSPHORUS CONTENT OF PRINCIPAL GRASSES OF
SHORTGRASS PRAIRIE
Growth Stage
Average
Date of
Collection
Percentage
of
Calcium
Fraps and
Fudge
Rating
Percentage
of
Phosphorus
Fraps and
Fudge Rating
Leaf
May 25
June 14
June 26
July 17
Sept. 28
April 8
0-390
0-274
0-277
0-291
0-337
0-361
Good
Fair
Fair
Fair
Good
Good
0-252
0-206
0-181
0-134
0 084
0-062
Fair.
Sheath
Fair.
Flower
Medium seed
Fair.
Deficient.
Cured
Deficient.
After winter exposure
Very deficient.
It is evident that these grasses are well supplied with calcium in virtually
all stages, and that there is no long period in the year when the content of this
mineral could be considered deficient. The phosphorus content is much less
satisfactory, becoming low by the time the seed stage is reached, and being
definitely deficient in the cured forage. The calcium-phosphorus ratio, while
53
quite low in the earlier growth stage?, is fairly high in the cured forage, and this
may be regarded as tending to intensify the effects of the low percentage of
phosphorus.
A similar condition holds true for most of the forages of the other range
zones. While some of the broad-leaved species are higher in phosphorus than
the grasses, their content of this mineral usually is low when in the cured stage of
development.
It would appear that in general, the native forages of southern Saskat-
chewan and Alberta have sufficient calcium for grazing animals. With phos-
phorus the situation is quite different. This mineral, while present in fair
amounts in the earlier growth stages, is deficient in the cured forage of most
species. The seasonal variation in phosphorus content of forage in the Short-
grass Prairie area is indicated in Figure 12.
.260
.250
.240
.230
.220
_
.210
.200
.190
.180
_
.170
_
.160
-
1 ~
.150
.140
.150
_
.120
_
.110
_
.100
.090
.080
-
.070
.060
.050
_
.040
_
.030
_
.020
.010
-
APR. KAY
JUNE JULY AUG. SEPT. OCT.
NOV.
DEC. JAN.
FSB. MAR.
Figure 12.
-Variation in phosphorus content of Shortgrass Prairie forage throughout the year.
Horinzontal line at .080 per cent indicates a definite deficiency for range livestock
while anything below 0.120 per cent is considered to be low.
These findings are of particular significance in the southern part of the
two provinces where livestock are grazed out during the winter. In the Sub-
montane and Forest zones there is less winter grazing and the nutrition of the
livestock depends primarily on the quality of the hay fed.
The phosphorus deficiency existing in the cured vegetation of the prairies
is reflected in the condition of the livestock feeding on this forage. Severe
deficiency diseases such as found in South Africa do not occur normally, but
many milder symptoms of mineral deficiency are present. Depraved appetite
among stock with consequent bone chewing has been reported from many
localities, while cases of animals with urinary calculi (stones) have become
increasingly common. It is thought that this latter condition is due in part,
at least, to a lack of balance between phosphorus and calcium. Other ranchers
have reported poor calf crops and reproductive troubles in livestock which
appear to be associated with mineral deficiency.
54
This lack of phosphorus in the native forage could be remedied probably
by the application of commercial fertilizers to the pastures, as indicated by
data presented earlier in this publication. A cheaper and more practical way
is to add a mineral supplement directly to the diet of the livestock. A suitable
supplement for this purpose is monocalcium phosphate. In its commercial form
this product contains about 18 per cent' phosphorus and 15 per cent calcium.
Bonemeal may be used also but its phosphorus content is slightly less than that
of monocalcium phosphate while it contains about twice as much calcium. The
higher calcium content of bonemeal usually is of no advantage since most range
species are well supplied with this mineral. It may be a decided disadvantage
where the calcium-phosphorus ratio of the forage is unduly high. This latter
condition is common in cured range forage.
Monocalcium phosphate may be fed alone in troughs or mixed with the
salt supplied to livestock. One pound of the phosphate to two pounds of salt
is a suitable mixture in most cases, but the proportions may be altered as desired.
Livestock will eat the mixture readily and it has been found that the con-
sumption of salt often drops when monocalcium phosphate is available. The
use of rock phosphate or superphosphate is not recommended as these sub-
stances may contain fluorine which is harmful to livestock.
A large number of stockmen in the area covered by this study are feeding
a phosphorus supplement, usually monocalcium phosphate, to their livestock.
Very few who once adopt this practice ever abandon it, since the results obtained
leave little doubt as to the benefits to be derived. Larger calf and lamb crops,
heavier calves and lambs, better condition of the stock in the spring and free-
dom from depraved appetite are some of the benefits reported. The frequency
of cases of urinary calculi appears to be reduced in some districts.
The need for a mineral supplement is greatest in the late fall and winter
when only cured forage is available in the pastures. However, the results
obtained on some ranches indicate that feeding smaller amounts of phosphate
during the remainder of the year may be beneficial in certain areas.
In zones where the native pastures are used mainly during the summer
grazing season (April or May to October), the need for mineral supplements
may not be so great. In certain areas, however, phosphorus may be deficient
in the forage even during the summer. Deficiencies may occur also where live
stock are wintered on low grade hay. Data presented earlier indicate that
native slough hay often is low in phosphorus, particularly if cut late in the
season. Many samples of such hay have been found to have a phosphorus
content of only 0-110 per cent which may be regarded as a minimum require-
ment for dry animals and too low for pregnant females. Where animals are
being fattened, the phosphorus requirements are high. Beeson and co-workers
(2) in Idaho have reported that a phosphorus content of 0-180 per cent was
required for best results in fattening steer calves.
The results obtained by feeding mineral supplements in other mineral-
deficient areas of the world have indicated the value of this practice. In South
Africa, diseased conditions of livestock resulting from a lack of phosphorus have
been remedied. In New Mexico, Knox and Watkins (28) have reported several
benefits from the feeding of phosphorus supplements. A smaller death loss in
newborn calves, better calf crop, greater weight of calves and lambs at weaning,
greater gains in weight by cattle and higher wool production from range ewes
are the principal benefits. Similar results have been reported from other parts
of the United States and from Australia.
This discussion has dealt with the mineral needs of range livestock feeding
on pasture or native hay in the area covered by this study. Hence the emphasis
has been placed on phosphorus, since it is the mineral most often deficient under
these conditions. The mineral situation is not identical, however, in all parts of
Western Canada or with all classes of livestock and all types of feed. In certain
55
areas other minerals, especially calcium and iodine may be deficient in pasture
and hay crops. Certain classes of stock such as dairy cattle have particularly
high mineral requirements and may require a supplement of both calcium and
phosphorus. Livestock being fed considerable amounts of grain or other con-
centrates low in calcium and rich in phosphorus are likely to develop a calcium
deficiency.
In cases where both calcium and phosphorus are needed, bonemeal gives
very good results. Steamed bonemeal contains about 32 per cent of calcium
and 15 per cent of phosphorus. Where calcium alone is needed, ground lime-
stone is a satisfactory supplement. A deficiency of iodine may be remedied by
feeding commercial iodized salt or by adding a solution of potassium iodide in
water to ordinary salt.
The object in all cases should be to supply the minerals likely to be deficient
in view of the composition of the feed being used and the requirements of the
animals being fed.
SUMMARY AND CONCLUSIONS
The results of chemical analvses of slightly over one thousand samples,
representing the principal native forage plants of southern Alberta and Saskat-
chewan are presented in this publication. The relation of these data to live-
stock production and grazing practices in the area is discussed.
The study was begun at the Dominion Range Experiment Station, Many-
berries, Alberta in 1927, and has been conducted also at the Dominion Experi-
mental Station, Swift Current, Saskatchewan since 1938.
The area included in the .study corresponds roughly to that embraced by
the Brown and Dark Brown Soil zones, along with certain additional areas in
the Cypress Hills and Rocky Mountain Foothills.
The climate of the area is characterized generally by light and variable
precipitation, a relatively high evaporation rate, great extremes of temperature,
high and frequent winds and abundant sunshine. The driest region is that lying
south of Medicine Hat, Alberta and precipitation increases east, north and west
'of this area.
The soils of the region belong mainly to the Brown and Dark Brown zones,
but smaller areas of Shallow Black, Black and Grey Forest Soils occur. Very
sandy soils are found in some portions, particularly in southwestern Saskat-
chewan.
The native vegetation of the study area consists mainly of Shortgrass and
Mixed Prairie, but Submontane Prairie and both deciduous and coniferous
forest occur in the Cypress Hills and Rocky Mountain Foothills. The sandhill
areas have a characteristic plant cover which includes grassland, shrub and
even patches of woodland.
In regard to technique, each sample was restricted to one species in one
stage of development, and sampling was done in such a manner as to simulate
grazing. In most cases samples were taken at definite sites, and the more
important species were collected in each of several growth stages for a number
of years. The species of the Shortgrass Prairie were studied most intensively
and those of the forest areas least.
The chemical composition of the forages studied was found to change
greatly during growth development. The young leafage is rich in protein and
minerals and relatively low in crude fibre content. The percentage of protein,
ether extract and phosphorus drops sharply from the leaf to the flowering stage
and then declines more gradually until curing occurs. The content of crude
fibre and nitrogen-free extract increases throughout growth development. A
further decline in percentage of protein, ether extract and phosphorus as well
as a slight drop in nitrogen-free extract occurs in cured forage which is exposed
over winter.
56
This seasonal change in chemical composition is characteristic of all classes
of native and introduced forages. It is most marked in the grasses of the Short-
grass Prairie where curing of leafage begins fairly early in the summer.
The principal grasses of the three prairie zones are much alike in chemical
composition. Sandhill grasses tend to be slightly lower in percentage of protein
and phosphorus and higher in crude fibre than those of normal prairie soils.
Broad-leaved forages of all zones are generally higher in protein and minerals
and lower in crud^e fibre than the grasses.
Analyses of the principal grasses and sedges of native meadows indicate
that these species compare favourably with upland species in nutrient content.
However, there is a rapid decline in quality after the flowering stage is reached,
.particularly in the sedges. The data indicate the importance of early cutting
of native meadow hay.
Analyses were made of samples of three commercially grown forages, namely
created wheatgrass, common brome and slender wheatgrass. These species all
tend to be slightly superior to the common native grasses in nutrient content
in the earlier growth stages but not when in the cured condition.
Statistical analyses of the data indicate that the leaf and flowering stages
are best for the comparative study of the chemical composition of different
species, since the variability of most constituents is at a minimum in these
stages. There is a strong positive correlation between protein and phosphorus.
Crude protein and phosphorus are negatively associated with crude fibre and
nitrogen-free extract. Statistically significant differences in the percentage of
protein, crude fibre and phosphorus exist between most growth stages of the
main prairie grasses.
Separate analyses of leafage and culms and of grass in the leaf stage at
various times during the grazing season indicate that seasonal changes in
chemical composition are due both to the development of flower stalks and to
maturing of the leafage.
Samples of native grasses collected at the Manyberries Station during
years differing considerably in precipitation revealed <a significantly higher per-
centage of phosphorus in the flowering and seed stages of plants grown in the
moister years.
The effects of soil type on the chemical composition of species were studied
in the case of a loam compared to a very sandy soil in the same climatic region.
The percentage of phosphorus was significantly lower in the samples grown on
the sand, but the content of other constituents was not affected appreciably.
The effects of top dressing of commercial fertilizers on two types of Short-
grass Prairie were studied. Significant increases in phosphorus content of the
herbage resulted from applications of phosphatic fertilizers. Nitrogenous fer-
tilizers gave consistent increases in protein content only on the vegetation of
silt loam alluvial soils low in nitrogen.
Studies of the seasonal gains of range cattle at the Manyberries Station
indicate that best gains are made in the early and midsummer period with very
little gain after the end of September. These results are in accord with the
seasonal decline in quality of the range forage and indicate the advisability of
marketing grass cattle early in the fall unless supplementary feed can be sup-
plied to maintain a high rate of gain.
In general, the native forage species studied appear to supply the require-
ments of range livestock reasonably well except in the matter of phosphorus.
The content of this essential mineral is fairly high in the young grass, but
declines greatly with growth development and is definitely deficient in the cured
forage. The remedy for the deficiency thus created is the feeding of a phos-
phorus-rich supplement,' such as monocalcium phosphate during the late fall,
winter and early spring months. In s'ome areas it may be advisable to feed
some phosphorus the year round.
57
ACKNOWLEDGEMENTS
The authors are indebted particularly to the staff of the Division of
Chemistry, Science Service, Department of Agriculture, Ottawa for the chemical
analysis of all material used in this study. The carrying out of this project has
been facilitated greatly by the willing co-operation received from the Chemistry
Division.
The authors are indebted also to Mr. L. B. Thomson, formerly in charge of
the Range Experiment Station at Manyberries and now Superintendent of the
Dominion Experimental Station, Swift Current and to Mr. J. A. Campbell,
formerly Agricultural Supervisor at the latter Station for criticism of the manu-
script. Many helpful suggestions were received from Dr. W. B. Davidson,
Inspector, Dominion Health of Animals Division, Moose Jaw, Saskatchewan.
The help rendered in the collection of samples by Messrs. J. L. Bolton, J. A
Campbell, J. B. Campbell and N. A. Skoglund is acknowledged gratefully.
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59
CAL/BCA OTTAWA K1A 0C5
3 9073 00188296 0
APPENDIX
Common and Scientific Names of Plants Discussed in the Text
Common Name
A — Grasses,
Alkali cordgrass
Awned wheatgrass
Awned sedge
Baltic rush
Canada brome
Canada wild rye
Canby's bluegrass
Common brome
Common speargrass
Crested wheatgrass
Dwarf bluegrass
Fringed brome
Grama grass, blue grama
Green speargrass
Hooker's oatgrass
Idaho fescue
Indian rice
Junegrass
Little bluestem
Marsh reedgrass
Niggerwool
Northern reedgrass
Northern wheatgrass
Nuttall's alkali grass
Parry's oatgrass
Pinegrass
Plains reedgrass
Prairie muhlenbergia
Purple oatgrass
Reed canary grass
Rough fescue
Saltgrass, alkali grass
Sandgrass
Sand dropseed
Short-awned porcupine grass
Short-awned brome
Skyline bluegrass
Slender wheatgrass
Slough grass
Spangle top
Spike rush
Tall mannagrass
Three-square bulrush
Tufted hairgrass
Water sedge
Western wheatgrass
Wild barley
Wild oatgrass
Scientific Name
Sedges and Rushes
Spartina gracilis Trin.
Agropyron trachycaulum var. unilaterale
(Cassidy) Malte
Carex atherodes Spreng.
J uncus ater Rydb.
Bromus purgans L.
Elymus canadensis L.
Poa Canbyi (Scribn) Piper.
Bromus inermis Leyss.
Stipa comata Trin. and Rup.
Agropyron cristatum (L) Beauv.
Poa secunda Presl.
Bromus ciliatus L.
Bouteloua gracilis (H.B.K.) Lag.
Stipa viridula Trin.
Avena Hookeri Scribn.
Festuca idahoensis Elmer.
Oryzopsis hymenoides (R. and S.) Ricker.
Koeleria cristata Pers.
Andropogon scoparius Michx.
C alamagrostis canadensis (Michx) Beauv.
Carex filifolia Nutt.
C alamagrostis inexpansa A. Gray.
Agropyron dasystachyum (Hook) Scribn.
Puccinellia Nuttalliana (Schultes) Hitchc.
Danthonia Parryi Scribn.
Calamagrostis rubescens Buckl.
Calamagrostis montanensis Scribn.
Muhlenbergia cuspidata (Torr) Rydb.
Schizachne purpurascens (Torr) Swallen.
Phalaris arundinacea L.
Festuca scabrella Torr.
Distichlis stricta (Torr) Rydb.
Calamovilja longijolia (Hook) Scribn.
Sporobolus cryptandrus (Torr) A. Gray.
Stipa spartea var. curtiseta Hitchc.
Bromus breviaristatus Buckl.
Poa Cusickii Vasey.
Agropyron trachycaulum (Link) Malte.
Beckmannia Syzigachne (Steud) Fern.
Fluminea jestucacea (Willd) Hitchc.
Eleocharis palustris (L) R. and S.
Glyceria grandis S. Wats.
Scirpus americanus Pers.
Deschampsia caespitosa (L) Beauv.
Carex aquatilis Whal.
Agropyron Smithii Rydb.
Hordeum jubatum L.
Danthonia intermedia Vasey
60
B — Forbs, Shrubs and Trees
American hedysarum
American vetch
Ascending milk vetch
Aspen poplar
Choke cherry
Dwarf phlox
Greasewood
Lance-leaved psoralea
Silvery lupine
Narrow-leaved milk vetch
Northern bedstraw
Pasture sage
Prairie goldenrod
Russian thistle
Sagebrush
Salt sage
Sandbar willow
Sandhill rose
Saskatoon bush
Shrubby cinquefoil
Slender sage
Small-leaved everlasting
Smooth aster
Spreading homalobus
Two-grooved milk vetch
Veiny peavine
Western sea blite
Western snowberry
Wild geranium
Wild licorice
Winter fat
Hedysarum americanum (Michx) Britton.
Vicia americana Muhl.
Astragalus striatus Nutt.
Populus tremuloides Michx.
Prunus melanocarpa (A. Nels) Rydb.
Phlox Hoodii Richards'.
Sarcobatus vermiculatus (Hook) Torr.
Psoralidium lanceolatum (Pursh) Rydb.
Lupinus argenteus Pursh.
Cnemidophacos pectinatus (Hook) Rydb.
Galium boreale L.
Artemisia jrigida Willd.
Solidago dumetorum Lunell.
Salsola Pestifer A. Nels.
Artemisia carta Pursh.
Atriplex Nuttallii S. Wats.
Salix interior Rowlee.
Rosa Macounii Greene.
' Amelanchier alnifolia Nutt.
Dasiphora jruticosa (L) Rydb.
Artemisia gnaphalodes Nutt.
Antennaria microphylla Rydb.
Aster laevis L.
Homalobus tenellus (Pursh) Britton.
Diholcos bisculcatus (Hook) Rydb.
Lathyrus venosus Muhl.
Suaeda depressa (Pursh) S. Wats.
Symphoricarpos occidentalis Hook.
Geranium Richardsonii Fisch and TrauP?
Glycyrrhiza lepidota Nutt.
Eurotia lanata (Pursh) Moq.
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