The effect of silage on the flavor and odor of milk

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UNITED STATES DEPARTMENT OF AGRICULTURE

\

Washington, D. C. Vv September 20, 1922

THE EFFECT OF SILAGE ON THE FLAVOR AND
ODOR OF MILK.

By JAMES A, GAMBLE, Professor of Dairy Husbandry, University of Maryland,
collaborator, and ERNrEsT KELLy, in charge of Market Milk Investigations,
Dairy Division, Bureau of Animal Industry.

CONTENTS.
Page. Page.
Causes ok taints in-milk S202 1 | Experiments with alfalfa silage____ 15
Description of methods used in ex- Experiments with sweet-clover silage 17
perimental wOtk@==—eees se ae SS 2 | Experiments with soy-bean silage__ 19
The feeding of silage-—_—_..__—-—- 5 | Discussion of legume-silage experi-
Experiments with corn silage------_ 5 TRENT eee se SR eee See et eae Dill
Effect of condensing on silage- Part played by aeration in reducing
MavOQred sa kes ee 13 silage flavors and odors__-----_- 21
Feeding spoiled silage_________ 13 | Good flavors and odors in milk_~~-_~ 22
Discussion of corn-Silage experi- Conclusion sas ae ee 23
TTT See es ere a 14> |Sliterature: cieds == = ee 23

CAUSES OF TAINTS IN MILK.

Cow’s milk invariably has a more or less pronounced flavor and
odor, but comparatively little is known concerning the substances
contributing to these characteristics. The flavors vary from those
that are pleasing to the taste to others which make the milk objection-
able and unpalatable. It has been observed by several investigators
that regardless of the feeds used and care taken, each cow imparts
to her milk a more or less pronounced individual taste. In a row of
cows receiving the same feed and care, the authors have observed
bitter, strong, salty, and flat milk as well as that having a very pleas-
ing flavor. Several of these if sold alone would have been rejected

Norrt.—The authors acknowledge their indebtedness to T. E. Woodward, of the Dairy
Division; also to W. R. Hale, J. B. McNulty, and J. A. Converse, who made the work
possible through their supervision of the experimental barn. They also extend. their
thanks to R. J. Posson, C. J. Babcock, and all other members of the Dairy Division and
University of Maryland staffs who assisted in passing upon the many samples of milk

and cream taken for this work.
108550°—22 1

9, BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

by consumers, yet when all were blended into the mixed milk of the ©
herd, the resulting blend was pleasing to the taste.
Flavors and odors in milk result from four causes:

1. The internal or physical condition of the individual cow.

2. Those absorbed within the body of the cow from highly flavored feeds.
3. Odors absorbed into the milk after production.

4. Bacterial development within the milk on standing.

Flavors and odors of the first and second classes are more notice-
able just after the milk is drawn and usually do not increase with —
time. Those of the fourth class become more apparent after some
time has elapsed. This bulletin considers principally the factors in
Groups 2 and 3, although information regarding Group 1 is brought
out by the investigation.

Milk of pleasing quality is usually produced on farms making a
specialty of high-grade milk. On the other hand, the great bulk of
the country’s supply is produced on farms where milk production is
but one of several farm activities, and, as a result, less time is avail-
able for controlling the factors which affect deleteriously the flavor
and odor of milk. With the exercise of a few precautions, however,
some of the defects found in market milk may at least be alleviated.

Factors affecting the flavors and odors of milk have been investi-
gated extensively, and much excellent work pertaining to the subject
published. However, such work has largely dealt with the subject
in a general way. The authors of this bulletin have studied the
problem from a somewhat different angle. The endeavor has been
to suggest methods of assistance to the average dairyman in the pro-
duction of milk reasonably free from the feed taints too frequently
complained of in market milk.

The objects of this investigation therefore may be outlined as
follows:

1. To determine whether or not the feeding of the different silages does
affect the flavors and odors of milk,
2. If such is the case, to determine how these silages may be so fed and

and the milk so handled as to UN ENZS their effect on the quality
of the product.

DESCRIPTION OF METHODS USED IN EXPERIMENTAL WORK.

For the experiments, a small barn was constructed at the United
States Department of Agriculture Dairy Experiment Farm at Belts-
ville, Md. The building was of wooden construction throughout and
was divided into two parts, one part providing space for four cows.
The material used for floors, walls, and ceiling was No. 1 tongue-and-
eroove pine. Building paper was placed on the outside walls of the
part used for a stable. to make the building as free as possible from
drafts. Ventilation was provided by doors and windows.

The stable contained approximately 250 cubic feet of air “space
for each of four cows, or about one-half the air space required by

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 3

most city regulations, The object was not only to get a milking cham-
ber which would hold odors, but, by cutting down the space one-half,
to intensify still further the degree of feed odors in the stable air.
This condition was necessary during the absorption work of the in-
vestigation. The silo was at a considerable distance from this barn.

Four cows, each giving about 10 pounds of milk daily, of approx-
imately 4 per cent butterfat, were selected from the Dairy Division
herd. Only those animals which gave milk free from decided off
flavors and off odors were selected and these were transferred to
the small barn. The milk in all cases was drawn by milkers who
‘gave close attention to the cleanliness of the cows and stable and of
their own hands.’ The cows were alternated from time to time in
order to equalize any abnormal results due to the milk of any indi-
vidual animal. For example, in working with the first absorption
phase, each pair of cows was milked outside the barn on alternate
afternoons. At intervals, the individuals in each pair were inter-
changed.

_ During these experiments the cows when producing the check
samples were fed on a basic grain and hay ration which did not ap-
|preciably affect the flavor and odor of the milk they produced.

In all the work, the milk from the different pairs was drawn into
sterilized, covered pails, and the milk from each pair strained through
filter cloth into a separate can that had been sterilized. The utensils
were steamed in a sterilizer for 30 minutes, and afterwards allowed
to remain there until used.

METHOD OF SAMPLING.

After milking, the two cans of milk were promptly carried from
|the barn to the milk room, the milk in each can stirred, and samples
jtaken. The milk from ech pair of cows was emptied into a gravity
\creaming can and with the samples was placed in a refrigerator which
}eooled and held it below 50° F. The next morning dye dean le
lin the different cans was drawn off and samples of the cream taken.
- When the effect of aeration was studied, half of the warm milk
}from each pair of cows was aerated by passing it over a clean surface
cooler, the milk resampled, the remainder placed in the refrigerator,
the milk allowed to cream, the skim milk drawn off, and the cream
jalso sampled.

| When, in addition, it was desired to get a standard sample known
\to contain the flavor and odor of silage, part of the milk from the
| cows not fed silage and not exposed to the silage odor in the milking
|barn, while still warm, was redrawn through an apparatus contain-
ling the silage odor. This apparatus is shown in Figure 1. Ten
| pounds of silage, fresh from the silo, were placed in this “closed cham-
ber an hour before the redrawing took place.

4 BULLETIN 1097, U. S. DEESHESS OF AGRICULTURE.

The warm milk was poured into the funnel erected on top of this
box, and redrawn through the openings into a container resting on
the silage within the chamber. The odor arising from the silage in

a a ct eel 6 i i Be

2

ee os

lig. , 1.—Apparatus for drawing samples of milk through atmosphere saturated
with silage odor.

the closed chamber imparted to the warm milk, which was passing
through it, a decided silage flavor and odor. A portion of this was
drawn, cooled, and delivered with the other samples. All samples

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 5

were examined by men in the Dairy Division of the United States
Department of Agriculture and members of the Dairy Husbandry
Department of the University of Maryland.

METHOD OF EXAMINATION.

Flavors and odors are more apparent when the milk is at body tem-
perature. For this reason all samples, before being submitted to the
different judges, were heated in a water bath to about body temper-
ature.

Some flavors and odors, because of familiarity, are quickly recog-
nized by some people, and because of unfamiliarity may not be so
quickly recognized by others. Standard samples of silage-flavored
milk were provided to supply this information. When the portions
were warmed and ready for examination, the sample containing the
known silage flavor and odor was passed around and examined, so
that the different men might have a measure for determining whether
or not any of the other samples contained a silage flavor or a silage
odor or both. Each man was furnished with slips upon which to
record the flavor and odor in the different samples submitted to him.
At the end of each phase of the work, the information on these
slips, when compared to the key containing the history of each sam-
ple, furnished a basis for conclusions.

THE FEEDING OF SILAGE.

Ever since silage came into use as a feed for dairy cattle more or
less controversy has taken place regarding its effect on the flavor
and odor of the milk produced. It has frequently been said that
the feeding of silage to milking cows gives rise to disagreeable
flavors and odors. So much has appeared on the subject that health
authorities 1 in some cities have incorporated in their city milk laws
regulations relating to the handling and sale of milk produced by
cows fed silage.

EXPERIMENTS WITH CORN SILAGE.

During the first three weeks that the cows were in the specially
constructed barn experiments were carried on for the purpose of
determining the combination of concentrates and roughage for a
basic ration which would not interfere with the flavor and odor of
the milk normally produced by the cows selected for the work.
When this combination had been obtained the barn and the cows
were carefully cleaned.

1. EFFECT OF CORN-SILAGE ATMOSPHERE ON FLAVOR AND ODOR OF MILK.

On alternate days 2 cows were removed to the outside one hour
before milking and 150 pounds of corn silage, fresh from the silo,

6 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

was spread on the platform underneath the 2 cows remaining in the
stable and the doors and windows tightly closed. During the inter-
val before milking, the silage odor so permeated the stable air that
by the time milking was started a decided silage odor was present.
“Tt will be noted that the quantity of silage spread out would have
been equivalent to 75 pounds per cow in an air space of approximately
500 cubic feet. ‘Table 1 shows the result of the experiment.
Particular attention is called to the extreme condition of barn-air
saturation used in this experiment. This exaggerated condition
was obtained for the purpose of ascertaining whether or not the so-
called silage flavor and odor might be air-borne to milk under extreme
barn conditions. No legitimate excuse can be conceived for the pro-
duction of milk in a barn without ventilation or with the small }
amount of air space used in this work to determine the above point.
Manure was removed once each day and the barn thoroughly aired.

TABLE 1.—Hffect of milking in stable air saturated with silage odor,

Cows milkedin | Check cows milked }
silage, atmosphere. in open air.

Result of sampling.

Milk. Cream. Milk. Cream.

Nim pberiotexamina tions: - oes soso se lee Ee eee eee 415 415 415 415
Off Mavorsesss- ee Ses ee a ee eee 96 103 Leos oe
IN OYOPAAV OL oe. Sie oe eee SS ec ee 319 312 364 358 ;
OnOd OF Rae aa eee es So SS ee 51 77 19 31
INOLOMMOG OIE ese 2 Sas So ss See ee eee 364 338 396 384

One of the most interesting points brought out was that although
in at least one-fourth of the cases the milk produced by the a1
milked in the barn under these extreme conditions took on the off
flavors and odors present in the barn air to a sufficient degree to be-
come apparent to those looking carefully for them, it certainly did
so to a less extent than is commonly supposed. The terms used in
describing the off flavors and odors were, “barny,” “ flat,” “slightly |

oft off, vote slightly strong,” and “ slight feed.” It was observed
that denon and odor in the milk were designated by the matter witht |
which they were associated. The off flavors and odors were found
more often in the cream than in the milk. This would indicate that }
the fat of the milk absorbs off flavors to a greater degree than the }
milk plasma. |

While off flavors were noted in approximately one-fourth of thal
cases, a large percentage of these were reported as “barny,” “ strong sg
and “ off,” with but few notations of “slight feed.” :

The terms used to describe the odors of the milk produced in thal
closed stable were the same as those used to describe the flavors,}
except that the terms “ barny ” and “ musty ” were used more often.

-

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. i

From this work it is apparent that under these extreme conditions,
not approached on dairy farms, the silage flavor and odor may, to a
limited extent, be air borne to milk during production.

“ Natural,’ “normal,” “good,” and “excellent” were the terms
used in describing the flavor and odor of the milk produced outside
of the stable by the check cows in almost 90 per cent of the cases. In

45 out of 415 examinations, “slightly flat,” “flat,’ “slightly salty,”

“ shehtly off,’ and “ off” were used, and in 6 cases the term “ slight
feed.” All these terms except the last are employed in describing
what are known as individual flavors. If we assume that a like
number of the 96 off flavors in the milk produced inside the stable
were also individual taints, this would reduce the possible number
affected by the barn air in Table 1 to 51 samples out of 415, leaving
364, or close to 90 per cent, which did not absorb sufficient silage
edors during the milking in the closed stable to be discernible to those
looking carefully for such flavors.

2. FEEDING CORN SILAGE BEFORE MILKING IN UNVENTILATED BARN.

Having determined the effects of an intense silage atmosphere on
the flavor and odor of milk under the extreme conditions which pre-
vailed in Experiment No. 1, the next step was to determine the effects
under extreme conditions on the farm. In this experiment the air
saturation arose from the silage which was fed to the cows in the
barn. The cows were given all the corn silage they would consume,
each cow receiving from 380 to 50 pounds in two feedings—one hour
before milking in the morning and one hour before milking at night.
The barn doors and windows were closed after each feeding. Dur-
ing this experiment the milk and cream samples were examined by
39 different men. :

TABLE 2.—Effect of feeding 15 to 25 pounds of corn silage per cow before each

milking in an unventilated barn.

Check cows not fed

Cows fed silage. silage.

Result of sampling.
Milk. Cream. Milk. Cream.

LS UEEN SOL Ot EBL TOMS. = a ae Sen eb or ese oe eeeeseneeo coer os coc 346 | 346 346 346
iiss {6 2 a ee ie eee nee 313 | 315 30 30
WO Wirt GOT. 1 ee Be eae eoe nO ep Sen perseaaEacicoss5osec 33 31 316 316
OTL OG OS eee 5 een cile ccin nicl oo vice mlneremiaemielel= 318 317 29 30
SINONOETA OG Oe ase sale eae Sin rice oc nee ns wn olainlelsleleenici= = 28 29 | 317 316

In almost 90 per cent of the cases the terms used in describing the
flavors present in the milk from cows fed silage were “ very slight
feed,” “slight feed,” “feed,” “strong feed,” “sweet,” “fermented,”
“malt,” “slight silage,” and “silage.” From this it is apparent that

8 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

when from 30 to 50 pounds of silage were fed daily to cows in two
feedings, one hour before each milking, in an unventilated barn, a
feed flavor and odor were imparted to the milk of the cows re-
ceiving silage.

The flavors and odors in the milk and cream from the alternate
cows not receiving silage were usually described as “ good,” “ excel-
lent,” “mild,” “natural,” and “normal.” The milk from the cows
not fed silage furnished a check on the effects of the odors present in
the barn air. Table 2 shows conclusively that when cows were kept
in an unventilated barn in which the corn-silage odor was present to
a greater degree than under reasonably good farm feeding conditions
the examiners, looking painstakingly for such, did not find a feed
flavor and odor except in a comparatively few cases. ‘These were
silage taints probably due to carrying over such taint within the body
from previous feeding, as demonstrated in subsequent experiments.
These results show that the more or less common opinion that silage
flavors are air-borne to milk is not true to the degree commonly sup-
posed. They also show that milk from cows fed silage under the
conditions of this experiment does take on, through the body, the
silage flavor and odor.

3. FEEDING 10 POUNDS OF CORN SILAGE BEFORE MILKING.

Having determined that the odor of corn silage is usually body-
borne to milk, the next step was to ascertain the number of pounds
of corn silage which could be fed to cows one hour previous to milk-
ing before such milk would take on sufficient silage flavor and odor
through the body to be recognized by those looking carefully for
the same. Table 3 shows the result from samples drawn from the
mixed milk of cows each receiving 10 pounds of silage. The barn
was well ventilated in this and all experiments which follow.

TABLE 3.—EHffect of feeding 10 pounds of corn silage per cow once a day one hour
before milking.

Milk irons cows fed
silage.
8 Milk from
Result of sampling. = Pe =e PCOMeOn
Before | After |fedsilage.
aeration. | aeration.

Number of examinations.................-- MNS 0 ty Ce ee eee 51 51 51

OPP Ma WOret oe eet seee ee wis Sie aes bo Cicintand Sc ae aS Re a A+ 38 2
INO OM: Hav On eceas eee ee eee oie we ose ce See ee 7 BY |i 49
OME OGD ONS Sse Sees a oinie Bae ie ood Sa cic wie Sow as oats ee ae eee 41 35 2
ING Of OOF. fis < Seen amneacinem- occ penne «oo. as Cee rece 10 16 49

The flavors and odors of milk from the cows fed silage were de-
scribed as “slight feed,” “sweetish feed,” or “silage.” These re-
sults show that the feeding of 10 pounds of corn silage to cows one
hour before milking gave the milk a sufficient feed flavor to be recog-

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK, 9

nized in over 85 per cent of the cases. Although sufficient flavor and
- odor were present in the milk to be detected in this number of cases
by men examining the milk carefully, it is probable that the feeding
of 10 pounds of silage, as above, did not affect the milk sufficiently
to be noted by the average consumer.

EFFECT OF AERATION.

To determine the effect of aeration on the feed flavor and odor
present, the same milk, after being sampled and while still warm,
was passed over a surface cooler and resampled. The results in
Table 3 show that when the milk was aerated a part of the feed
flavor and odor it contained was removed. The table shows that, in
the aerated milk, feed flavors and odors were noted in six samples
fewer than in the milk before aeration. They were reduced in de-
eree also in the other samples.

The cows not receiving silage occupied and were milked in alter-
nate stalls from those receiving silage. In the table it is seen that
in over 96 per cent of the cases no feed flavor or odor was observed
in the milk drawn from cows standing in the same barn side by side
with the cows fed silage.

This experiment shows that the feeding of 10 pounds of corn silage
one hour before milking gave a perceptible feed flavor and odor to
the milk. It further shows that if such milk is carefully aerated
while still warm, the degree of flavor and odor may be materially
diminished. In the opinion of the judges, the silage flavor present in
the milk often enhanced rather than detracted from its palatability.

4. FEEDING 20 POUNDS OF CORN SILAGE BEFORE MILKING |

In the next experiment, the quantity of corn silage fed before milk-
ing was increased to 20 pounds.

TABLE 4.—/ffect of feeding 20 pounds of corn silage once a day one hour before

milking.
Milk from cows fed
silage. °
sae [Milk from
Result of sampling. Spe cows not
Before After | fedsilage.
aeration. aeration. |
ISS SyTT Epa OT GATTI Se Gee ee ee Se eee 25 25 25
RE art eee See FF ee. a ee Ee Noe 18 18 | 0
RUS aif Gesrdi ies oo ee ae eee oe a a ee ee 7 7 | 25
RGF. 2 een ahah ee ee ae te ee eS 25 20 0
INC OT Past. a ee ee ae ee 0 5 | 25

The results in Table 4 show that the feeding of 20 pounds of corn
silage each to cows one hour before milking gave the milk sufficient
feed flavor or odor to be detected in all of the samples. The flavors

108550°—22

10 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

and odors present were described as “slight feed,” “ feed,” “silage,”
and “strong feed.”

During the latter part of this experiment it became necessary io
use silage which had been in the silo for four or five years. This
silage had a milder flavor than the 8-month-old silage fed in 10-
pound lots during the previous experiment, and gave the milk a
milder silage fiavor. This suggests that the degree of odor present
in the sete helps to determine the degree of feed ATE and odor
imparted to milk.

EFFECT OF AERATION.

After the samples of milk from the silage-fed cows were taken, the
remaining milk, while stili warm, was aerated by passing it over
a surface cooler. Although diminished by aeration, the feed odor
was still present in sufficient degr ee to be noted in over 70 per cent of
the flavor examinations and in 80 per cent of the odor examinations.

Table 4 also shows the conditions noted in the check samples from
cows not fed silage. The terms used by the judges in describing the
flavor and odor in these samples were “ natural,” “ normal,” “ good,”
and “excellent.” In no cases were the judges able to detect any
feed flavor or odor in the milk drawn from the cows not receiving
silage. This agrees with previous work covering this phase.

It is apparent that feeding 20 pounds of corn silage one hour before
milking does affect the flavor and odor of milk to an appreciable
extent. It is also apparent that aeration diminishes the degree of
the feed odor imparted by the silage. The experiment fee sug-
gests that when 20 pounds of 5-vear-old silage are fed, sufficient will
pass through the body to affect the taste and smell of the milk pro-
duced. While the feed flavor and odor in this milk were sufficiently
prominent to be apparent to some consumers, it was the opinion of
the judges that after aeration it would be accepted in a great many
cases without complaint on the part of the consumer.

5. FEEDING 30 POUNDS OF CORN SILAGE BEFORE MILKING.
The quantity of silage was next increased to 30 pounds per cow.

TABLE 5.—LHffect of feeding 30 pounds of corn silage once a day one hour before

nulking.
Milk from cows fed
ilage.
oe Milk from
Result of sampling. a Comoe
Before | After |fdsilage.
aeration. | aeration.

Number oftexaminationsi sco ce ooo. oe. 5. eee eee 46 46 46
Off flav orice den stds Codie oe eek ios ooo sn 46 46 1
INO! off flavors si trees os cctesesewonee ioc. Gee eee 0 45
Off odor. tare es ciawbink bod dede owen ndcc 0. 46 46 1
ING OfsOd OF 6 Ses cine tae daar soc d cba c lets) eee eee 0 45

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 11

The flavors and odors in the milk of the silage-fed cows were
noted as “fermented feed.” “ feed.” or “slight silage.” “silage.” or
“strong feed” in all cases. The results in Table 5 show that milk
from cows fed 30 pounds of corn silage before milking had a decided
feed flavor and odor. The taste and smell of the feed were noted in
every case by all the judges. In the opinion of these men, sufficient
was present to be noted by even those consumers giving but little at-
tention to the flavor and odor of the milk supplied them.

EFFECT OF AERATION.

Although a feed flavor and odor were noted by all the men who
passed upon the aerated milk, the degree present was diminished.
This shows that when silage is fed in these quantities just before
milking, aeration may be of much assistance in decreasing the flavor
and odor of silage.

The milk from the other 2 cows in the barn in alternate stalls
from those fed silage was examined as a check on the barn air and the
basic ration which all the cows were receiving.

Comparing the results in this experiment with those obtained in
Experiment No. 2, the effect of the new factor, ventilation, on the
flavor‘and odor of milk produced by cows not fed silage is strikingly
shown. (Compare the columns for the check cows in Tables 2 and
5). Proper ventilation may play an important part in ridding the
barn of manure oders. Adequate ventilation is, therefore, important
in limiting undesirable flavors and odors which may be absorbed
during milking.

This experiment also shows that feeding 30 pounds of corn silage
one hour before milking gives the milk a feed flavor and odor suffi-

cient to render it objectionable to most consumers. Another point

brought out was that, whether silage is fed immediately after being
taken from the silo or allowed to air somewhat before feeding, the
milk produced carries strong feed flavor and odor. This feed flavor
and odor had a tendency, however, to be stronger in the milk when the
silage was fed fresh from the silo. Even when as low as 10 pounds
of silage per cow were fed a silage flavor was imparted to 85 per cent
of the samples in a sufficient degree to be noted by those looking care-
fully for it. The degree of flavor, however, was much less than
when 20 or 30 pounds were fed in a like manner. It may be said
that not until 20 pounds or more were fed did the feed flavor and
odor become so pronounced as to make the milk decidedly objection-
able to a majority of consumers. In fact, it was the opinion of the
judges that the flavor imparted when 10 pounds of corn silage were

fed enhanced the palatability of the milk.

It was apparent that the greater the quantity of silage fed before
milking the more pronounced the feed flavor and odor. The ob-

12 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

servers noted that aeration diminished the degree of silage flavors
and odors to a greater extent as the quantity of silage fed was
increased.
6. FEEDING CORN SILAGE AFTER MILKING.

The practice of feeding silage after milking is recommended by
practically all authorities. The next step in this work was to de-
termine the quantity of corn silage that could be fed after milking
and not deleteriously affect the flavor and odor of the milk pro-
duced. Two of the cows were fed all the corn silage they would
consume in two feedings per day one hour after milking. One of
these individuals refused more than 30 pounds or 15 pounds at a feed-
ing, while the other readily consumed 50 pounds in two feedings of
25 pounds each. The milk from these cows, when mixed, represented
an average consumption of 40 pounds of silage per cow each day.

TARLE 6.—HLH/ffect of feeding 15 to 25 pounds of corn silage twice daily one hour
after milking.

Milk from cows fed
silage.
é Milk from
Result of sampling. oT = - ae COWS moL

Before After fed silage.
aeration. | aeration.

Nim beronexaminatvOns: ess) sce noo ee oe Oe eee eee 25 25 25
Orit iho) cess SAS Nee ee ene ene ee ORE Son Be eo oe Seccosacus 15 2 1
Novo fi Ha VOT swe sie an te ec is Se 2 eee eee 10 23 24
Off odo eek. clei snk ces ce | eee 12 2 aes
IN OxOfR.Gd ORS Sas ee toe oc Se Sato cass sone te eee eee eee | 13 23 | 24

The results in Table 6 show that when an average of 20 pounds
of corn silage per cow was fed just after each milking the milk took
on a slight feed flavor or odor in more than 50 per cent of the cases.
The flavor and odor detected were described as “slight feed ” and
“slight silage.” This shows that while the feeding of corn silage
after milking is to be recommended, such a practice does affect both
flavor and odor when fed under conditions similar to those prevailing
in this experiment. It appears also that while men accustomed to
examining milk closely detected a slight feed flavor and odor, it was
present in quantities too small to be objectionable to the average con-
sumer, as 40 per cent of the samples did not show these character-
istics sufficiently to be detected when the milk was carefully exam-
ined by experienced men.

It is interesting also to note that in the opinion of the majority
of the judges, the slightly sweetish flavor imparted enhanced rather
than detracted from the palatability of the milk. In no case were
the feed flavors and odors present to as great a degree as was found
in the samples from cows fed 10 pounds of silage one hour before
milking.

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 13
EFFECT OF AERATION,

This milk was afterwards aerated, resampled, and examined.
After aeration, instead of 50 per cent of the samples containing a
recognizable feed flavor and odor, it was observed in less than 10
per cent of the samples. From this we may conclude that careful
aeration of the warm milk from cows fed up to 20 pounds of silage,
twice daily after milking, will materially reduce the degree of feed
flavor present. Cows are usually fed less than 50 pounds per cow
per day. If this is fed after milking, and the milk carefully aerated,
_it is probable that the feed flavors and odors present will be so
slight as to be passed by the average consumer without observation.
It must be recognized, however, that this work was done with care-
fully made silage. It is also probable that the sudden feeding of
corn silage in quantities as great as 40 pounds a day to a cow not
accustomed to receiving it might have a more decided effect on the
flavor and odor of milk for the first few days, or until the cow’s
stomach became accustomed to handling this quantity. It was noted
that as each phase of the work with silage progressed the feed flavor
and odor were detected less frequently by the judges, even though
the same quantity was fed from day to day.

As a check on the cows fed silage, the milk from the other pair
standing side by side was sampled. The flavors and odors of these
check samples, with one exception, were described as “ normal,”
“natural,” “ mild,” “ good,” and “excellent.”

EFFECT OF CONDENSING ON SILAGE-FLAVORED MILK.

Ten gallons of milk from cows not receiving silage was passed
through a saturated silage atmosphere in the apparatus shown in
Figure 1. This gave the milk a more decided silage flavor and
odor than was observed when silage was fed even under the extreme
conditions of Experiment No. 2. The milk was then condensed in a
commercial apparatus and the resultant product sampled.

In the early days several large firms buying milk for condensing
purposes discriminated against milk from cows fed corn silage.
This examination was conducted to secure information on the effect
of silage on condensed milk. It was noted by all the judges that
the distillate taken from the silage milk during condensing con-
tained a concentrated silage flavor and odor, much more so than the
milk itself before condensing. It was noted also that the condensed
milk had much less silage flavor and odor than the milk from which
it was manufactured.

FEEDING SPOILED SILAGE.

Dairymen are frequently warned by authorities not to feed spoiled
silage because of its effect on the milk flavor. Experiments were

14 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

carried on with the feeding of decomposed silage taken from the
top of a silo when it was opened. From 5 to 15 pounds of this
material were fed to each cow one hour before milking. It was
noted that 5 pounds of this imparted a very strong flavor and odor
to the milk, described as “ resembling garlic” by several of those
who passed upon it. As much as 15 pounds of this material was
eaten readily by the cows under experiment. Even after aeration
it was found that when the quantities fed were as low as 5 pounds,
sufficient of the objectionable flavors and odors remained to render
the milk objectionable to the consumer.

DISCUSSION OF CORN-SILAGE EXPERIMENTS.

It is apparent that under the feeding conditions in these experi-
ments the danger of tainting milk during production by exposure
to stable air containing the odor of silage is not so important as
some have stated. It is shown, however, that ventilation plays an
important part in preventing the tainting of milk during milking,
and, further, that milk should be removed from the stable immedi-
ately after it is drawn. Statements have been made, and pos-
sibly it has been the general belief, that the greatest source of silage
flavors and odors in milk is silage-tainted barn air. These experi-
ments show that silage fiavors and odors are almost wholly taken
up by the milk within the body of the cow. Whether silage is fed
before or after milking, the barn should be ean! ventilated be-
fore milking is started.

In the feeding of silage before milking, these experiments show
that when as httle as 10 pounds to a feed was given, the milk took on
through the body of the cow a faint feed flavor and odor. As the
quantity was increased to 30 pounds at a feed, the degree of silage
flavor and odor was likewise increased. It is also shown that careful
aeration materially reduced the degree of both feed flavor and odor.

This confirms the work of Knisely (§') who reports that milk
from cows fed corn silage has a more pronounced odor than milk
from cows fed hay. King (7) also states:

It was demonstrated beyond. question that when silage is fed a short time
before milking, a sweetish odor is imparted to milk.

An article in Hoard’s Dairyman (7) states:

If silage is fed before milking, there is likely to be a silage odor in the milk.

Many fou workers have also pointed out these truths during the
last 20 years.

In the feeding of silage after milking, our results do not entirely
agree with some other workers. It was found that when as little as

1 The italic figures in parenthesis refer to Literature Cited at end of bulletin.

,
ee ee ee

eer ee

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 15

30 pounds daily was fed in two feeds after milking, the milk from
the cows showed a slight feed flavor and odor, and that when more
than 40 pounds per day were fed to cows, their milk carried con-
tinuously a slight silage flavor and odor. In this connection, it is
again pointed out as reported by Henry and Morrison (6), that as
feeding progressed the effects of the silage become less and less
apparent in the milk. In our work it was found that while this was
true when less than 35 pounds per day was fed to each cow, it was
shown that when over 40 pounds were consumed, the sweetish feed
flavor could always be detected. King (7) reports:

It was demonstrated that if silage is fed to cows just after milking, in a

majority of cases, milks so produced could not be separated by the sense of
smell from nonsilage milks.

Farrington (3) reports:

It has been repeatedly proved that silage can be fed to dairy cows without
tainting the milk, butter, or cream in the slightest.

The presence of a small but discernible amount of silage flavor in
milk need not perplex, however, for it is shown that careful aeration
will reduce this to a point where the feed flavor and odor will not
be detected by the average consumer.

Moderate quantities of corn silage properly fed to milking cows
have a tendency to enhance rather than to detract from the flavor
and odor of the milk. This is especially true of individual milks
normally flat or lacking in flavor.

EXPERIMENTS WITH ALFALFA SILAGE.

It frequently happens that farmers have difficulty in curing alfalfa
for hay. The first cutting is sometimes so full of weeds that it dries
slowly; in other cases a wet season interferes, while at other times
a threatening early frost makes immediate cutting of the last crop
expedient. Putting the green alfalfa into the silo has in many cases
meant saving the crop.

While some dairymen have used alfalfa silage with success, others
claim that milk spoilage is experienced. However that may be, a

_ great deal of alfalfa silage is now being fed. The experiments next

described were carried out to determine how this roughage, rich in
protein, may be fed so as to affect least deleteriously the flavor and

odor of the milk produced.

The alfalfa silage used was made from finely cut green alfalfa,
carefully packed in the silo.

1. FEEDING ALFALFA SILAGE BEFORE MILKING.

The first work covered the feeding of 5 pounds of alfalfa silage

one hour before milking. This quantity was gradually increased to

16 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

20 pounds per cow. The cows on experiment would not consume
more than this weight at a feeding.

TABLE 7.—Effect of feeding 5 to 20 pounds of alfalfa silage once daily one

hour before milking.

Milk from cows fed
silage.
Result of sampling. SS ee | COW SOE

Before After |fedsilage.
aeration. aeration. |

Number'of examinations ses. << oo. oo oc eee ee ee eee 11 | 11 11
Off: flavor ns: eee se bE os Se ee ee Taba 11 0
NOLO fa VOR ee a Se Tee ee ene 0 0 1l

The results in Table 7 show that the feeding of alfalfa silage to
cows one hour before milking imparted a feed flavor which could be
detected in all cases. The off flavors were described as “slight feed,”
“ feed,” “shight silage,” and “alfalfa silage” as the quantity was in-
creased up to 20 pounds. The odors were described with the same
terms. When the milk from the cows receiving 5 pounds was aerated
the flavor and odor were very faint. When 10 pounds per cow was
reached, the milk contained sufficient feed flavor and cdor even after
aeration to be ordinarily detected by consumers. When 15 pounds
had been reached sufficient was present, in the opinion of the examin-
ers, to cause rejection of the milk by the average consumer. Without

question, the cream from this milk would be rejected by the sweet-

cream trade.
EFFECT OF AERATION.

In this experiment it was noted that while aeration removed a
great part of the feed taste and aroma, sufficient remained to be
noted in all examinations.

Standing in the barn in alternate stalls were the cows which did
not receive alfalfa silage. It is seen in the table that no feed flavor
or odor was noted in the milk produced by these cows. It is to be re-

membered, however, that throughout this work, with the exceptions —

of Experiments Nos. 1 and 2, the barn was well ventilated.
2. FEEDING ALFALFA SILAGE AFTER MILKING

As in the feeding of corn silage the importance of feeding alfalfa
silage only after milking has been noted. To determine how much of
this may be fed per cow, after milking, without rendering the milk
objectionable to consumers, the following work, shown in Table 8,
was carried on.

‘Milk from

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 17

TABLE 8.—Hffect of feeding 5 to 20 pounds of alfalfa silage once daily one
hour after milking.

Milk from cows fed

Silage. -
: Milk from
Result of sampling. SSS ———] cows not
| Before After fed silage.
aeration. | aeration.
arse ONE< AUN GONS= 22 ne). eee 14 14 14
COSTE Shy ONS orn e ens Ney Sn ote Ts os et ei aes gr 10 : ) 0
ISP OEP UPS Rk Se ee ek ee PINE SS 71 ath 4 9 14
Bao serene ee te tT. . e e Rae ees. e 0
INGIOHZOU Oe en ee erent ea eT ee ee 6 9 14

In this experiment 5 pounds were fed to begin with, and this
quantity increased 5 pounds every two days up to 20 pounds, when
it was reduced to 5 pounds again, dropping 5 pounds every two days.
It was observed that the alfalfa-silage flavor did not become notice-
able in the milk until 10 pounds or more were fed. However, when
from 15 to 20 pounds were consumed at each feeding the milk took
on a decided feed flavor and odor.

When this milk was aerated the degree of feed flavor and odor
was decidedly reduced and was detected less often, as shown in the
table. This again shows the importance of aerating milk. It was
also observed that when the milk from cows receiving 10 pounds was
aerated all judges failed to detect feed flavors or odors.

This work indicates that alfalfa silage should be fed only after
milking, and that the milk should be well aerated while still warm.
The importance of this is shown by comparing the results in Table 7
with those obtained in Table 8.

EXPERIMENTS WITH SWEET-CLOVER SILAGE.

In some cases clover crops have been made into silage with fair
success. Where weather conditions interfere with the proper curing
of clover for hay it is sometimes put into the silo. It is well known
that the silage made from clover has a strong odor, necessitating care-
ful feeding to avoid tainting the milk. For this experiment silage
made from sweet clover, cut in fine lengths and tramped solidly,
was fed to the experimental cows. It was noted that the sweet-
clover silage had’ a more decided odor than the alfalfa silage.

~

1. FEEDING SWEET-CLOVER SILAGE BEFORE MILKING.

At the beginning of the work 5 pounds of sweet-clover silage were
fed one hour before milking. This was continued for several days;
afterwards the quantity was increased to 10 pounds and continued
for several days longer; then increased to 15 pounds. An effort was

‘

°18 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

made to increase the feeding to 20 pounds, but the cows refused to
consume that quantity at a feed. It was noted that even when 5
pounds were fed in nearly all cases the milk had a detectable feed
flavor and odor, and when the quantity was increased to 15 pounds
the feed flavor and odor became very objectionable. _

TapLe 9—Effect of feeding 5 to 15 pounds of sweet-clover silage once daily
one hour before milking.

| Milk from = fed |
‘Milk from
cows not

| Before After ‘edsilage.
| aeration. aeration.

Result of sampling.

Number of exantimations.—.-2 50 =) 2 = eee : 30 | ae 20
Off flavor. 2-2-1 Se ee ee eS eee 28 | 20 0
NOOSE Maver. =2028k Ss se ee et eS eS 2 | 10 30
Oil odors 35 ae ese ea 6 ee = RSP eee 29 21 8)

EFFECT OF AERATION.

When the milk from the cows fed up’to and including 15 pounds
before milking was aerated, the intensity of the feed flavor and odor
was diminished, as shown in the table. In the opinion of the judges
sufficient of the feed flavor and odor had been removed during aera-
tion to render the milk palatable.

This experiment shows that even as little as 5 pounds of sweet-
clover silage. when fed before milking, produced a feed flavor; 10
pounds produced a decided feed fiavor and odor, and 15 pounds so
increased the intensity as to render the milk, if unaerated, objection-
able to the average consumer. It is also shown that aeration so re-
duced the flavor and odor present, when 5 pounds were fed, as to
cause it largely to disappear. When 10 pounds were fed and the milk
aerated, the sweet-clover silage flavor and odor persisted. When 15
pounds were fed and the milk aerated, while the flavor and odor was
somewhat stronger, a decided reduction in the degree had taken
place. In the case of this silage, the odor, after aeration, seemed
more tenacious than the flavor.

In this experiment, as in others, check results were obtained with
alternate cows not fed silage. There was a total lag, feed flavor
and odor in the milk from these cows. -

2. FEEDING SWEET-CLOVER SILAGE AFTER MILKING.

The next experiment was carried on to ascertain the quantity of
sweet-clover silage that could be fed after milking and the methods
of handling necessary to overcome the objectionable effects.

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 19

TABLE 10.—Effect of feeding 5 to 15 pounds of sweet-clover silage once daily
one hour after milking.

Milk from cows fed

silage.

“Milk from
Result of sampling.

cows not
Before After |{edsilage.
| aeration. | aeration.

DPN DCHG eX AMNTMIALIONS == 2-221. 2... 2 1, eee 30 30 30
Oa AVOr se ee EL a = a er ih a 28 20 | 2
DLE TEEN Ges Re a OR oi ced I ies Pe Se 2 10 28
ChEOC OR ee ee ee ee ask Ye eee eee! 29 21 2
NID GUMOC) rs Se Ls Ee ee eee 1 9 28

The results with unaerated milk show that when sweet-clover silage
was fed after milking in quantities from 5 to 15 pounds, a feed flavor
and odor were imparted to the milk. In explanation of this table it
may be said that in 2 cases there were no feed flavors and in 1 case
no feed odor when 5 pounds were fed. When this quantity was in-
creased to 10 pounds, the notations were, “ slight silage,” and “ slight
feed”; when 15 pounds were fed the samples were marked “ feed,”
“strong feed,” and “clover silage.” Whik the feeding of sweet-
clover silage is a desirable practice from an economic standpoint, the
above results show that even when fed under ideal conditions it af-
fected the flavor and odor of the milk produced, 15 pounds, fed after
milking, tainting the milk sufficiently to be noted by the average
consumer.

EFFECT OF AERATION.

Aeration, however, produced a marked change in the degree of the
flavors present. By sprinkling the grain ration on the sweet-clover
silage, each cow consumed up to 15 pounds of silage at a feeding.
When this milk was aerated, in the opinion of the judges, the feed
flavor was sufficiently diminished to be unobjectionable to the ay-
erage consumer. These results show that sweet-clover silage should
be fed only after milking, and the milk should be carefully aerated
while still warm. : When this is done, up to 15 pounds at each feed-
ing may be fed per cow without permanently injuring the commer-
cial value of the product.

EXPERIMENTS WITH SOY-BEAN SILAGE.

Another protein roughage, soy beans, is also sometimes ensiled.
When put in the silo alone soy beans make rank-smelling silage. The
effect of this feed on the flavor and odor of milk is shown in the fol-
lowing experiments.

20 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.
1. FEEDING SOY-BEAN SILAGE BEFORE MILKING.

In feeding this material it was noted that 5 pounds gave the milk
a detectable feed flavor and odor. As the quantity was increased to
15 and 20 pounds, the flavors and odors present increased in intensity.

Taste 11—F fect of feeding 5 to 20 pounds of soy-bean silage once daily one
hour before milking. ; “i

Milk from | Milk from
Result of sampling. cows fed cows not
silage. fed silage.
INEM DeLiOn GxamMIn SblONS so 6 22 oe oo ae cole. ss Soo aie See eae See eres 16 | 16
OPM aVOrsc Seok oo oes Ae skid oh da ab 2 ee eee eee 16 1
INO OfR fla VOR ase oF Cee eee is sas Ss oe Boe oe ere rea 0) 15
OTRO OTS secre a a teins Im Se SIE Soe a= ie enn 16 | 2
IN OvOfMOd OG2 2 cate Ue eo Se ee Se ew ne ee ee ee eee 0 | 14

The milk from cows not receiving soy-bean silage was scored, as
usual, for a check, with the results shown in the table.

2. FEEDING SOY-BEAN SILAGE AFTER MILKING.

In feeding 5 to 20 pounds of soy-bean silage one hour after milk-
ing, it was noted that when the quantity fed reached 10 pounds, a
slight flavor resulted. This was increased in degree as the quantity
of silage given the cows was increased.

Aeration greatly reduced the objectionable flavor, although the
extent of the reduction is not shown in the table. When the quantity
fed after milking was again reduced to 10 pounds, a shght feed odor

vas noted by the judges after aeration.

TABLE 12.—H/ffect of feeding 5 to 20 pounds of soy-bean silage once. daily one
hour after milking. :

Milk from | Milk from

Result of sampling. cows fed -}| cows not

silage. fed silage.
Wumber ohexaminations: cs: he, ee ene 15 16
OPP MAVOR Se Se ee es oe eeaaio cule Sie Se tie e wales a a 12 0
IN(O Of MAVOL ours cere eee ee ee oy 2. 2 ee ere eee 4 16
OMOd OG S24 Fee ee ae cee es otk. 3 Se ae eee 12 0
IN OFOfROM OT Se ee ee ee Nee eS) pee ean 4 16

Again it is shown that the cows not receiving soy-bean silage,
standing in alternate stalls, produced milk not affected by the barn
kb

From the experiments with soy-bean silage it is apparent that
when this feed is fed one hour before milking, even in such small
amounts as 5 pounds per cow, it affects the flavor and odor of the

milk. Increasing the quantity fed increased the feed flavor. It is

a

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 21

evident that the proper way to feed this silage is after milking
and, further, that even when so fed in quantities from 5 to 20 pounds
at a feeding, most of the milk produced has a strong soy-bean silage
flavor and odor.

DISCUSSION OF LEGUME-SILAGE EXPERIMENTS.

The legume silages fed in this work were unusually dark in color
and had rank characteristic odors. The experiments show that they
should be fed only after milking and then in quantities of not more
than 15 pounds to a feed if milk reasonably free from feed taints is
to be dbtained.

Henry and Morrison (5) report that, “as a class, the legumes
have proved disappointing for silage when ensiled alone.” They
state further (4) that while alfalfa has been ensiled with entire
success, “often poor, vile-smelling silage is produced.” In regard
to soy-bean silage, Woll and Humphrey (/7) went so far as to say
that satisfactory dairy products could not be made when cows were
fed this silage. Woodward and McNulty (72) report that silage
made from clover, while palatable, has an objectionable odor ncces-
sitating care in feeding to avoid tainting the milk.

PART PLAYED BY AERATION IN REDUCING SILAGE FLAVORS AND
ODORS.

Silage is a palatable, wholesome feed for milking cows, the feed-
ing of which is generally conducive to economical milk production,
and it will continue to be fed on an increasing number of dairy farms
as its feeding value becomes more generally recognized. Lezumes
likewise will continue to be grown and fed in ‘ncreasing amounts for
much the same reason. Efforts will be made to save the crop by
ensiling just so long as wet seasons prevent its being cured into hay,
or when early frosts threaten its growth. In accordance with the
method of feeding practiced by busy dairymen, corn and legume
silages will continue to-be fed both before and after milking. Thus
cows that eat pasture weeds, such as garlic and ragweed, or are fed
silage, cabbage, or turnips before milking will continue to give
tainted milk. The milk from cows kept during certain seasons of
the year in unventilated, sometimes unclean, barns will continue to
be tainted. These feeding and barn conditions are still more general
than they should be, and, until they are corrected, the milk should be
taken from the stable as soon as drawn and aeration more generally
employed in removing immediately as much of these taints as possi-
ble while the milk is still warm. The experiments have shown that
this can be done easily and with beneficial results.

The process consists in bringing milk in thin streams into contact
with the air, thus permitting the escape of the volatile taint-bearing

22 BULLETIN 1097, U. S. DEPARTMENT OF AGRICULTURE.

substances. As ordinarily practiced, aeration has a double purpose—
first, to air the milk; and second, to lower its temperature. Russell
(10) reports “the method certainly has no disadvantages.” It
should be borne in mind also that feed and barn taints once re-
moved are removed permanently by the process. Marshall says (9)

“it is best accomplished immediately after milking.”

acid, hydrogen, and sulphid of hydrogen, and supplies the milk with
air so that in all probability the development of certain bacteria is
checked, which otherwise, if the milk had been filled in containers
in a warm and unaerated condition, would have imparted*to the
milk a shen dice guescile taste and adore the milk woul have been

‘smothered.’
PLACE TO USE THE AERATOR.

In aerating milk it should be borne in mind that the same condi-
tions which favor the escape of odors which the milk contains when
drawn from the cow are also conditions which permit the milk to
become tainted with odors from the outside. For this reason, aera-
tion should take place in a milk room in which the air is free from
bad taints or dust, and which is well ventilated.

GOOD FLAVORS AND ODORS IN MILK.

Tt is imaportant that milk have a good flavor and a good odor. It
is probable that some flavors and odors constantly present in milk in
time cease to be objectionable to the individual and are taken as a
matter of course. In some alfalfa sections of the United States the
so-called alfalfa taste is general in milk and in these sections is ac-
cepted without comment.

The work has shown that fine-flavored milk is an individual char-
acteristic of some cows. It may be that whole herds of cows giving
milk of desirable flavor will be assembled in the future, and the
effort made to fix and perpetuate this desirable characteristic by
breeding and selection.

Preventive measures are always best; therefore dairymen should
endeavor, first, to have cows and barns clean; second, to have cow
stables properly ventilated; third, to feed after milking those mate-
rials likely to taint milk; and fourth, to decrease feed and barn taints
by proper and immediate aeration. Finally, prompt cooling and
storing of milk at a low temperature will retard the development of
odors from bacteria] action.

As stated before, the cows used in these experiments produced daily
approximately 10 pounds of milk each. It is possible that with cows
of greater or less production different amounts of silage might be
fed with varying results as regards intensity of the flavor imparted

According —
to Ernst (2), “the aeration of milk permits the escape of carbonic -

A

3

EFFECT OF SILAGE ON FLAVOR AND ODOR OF MILK. 23

to milk. It is believed, however, that the conclusions state funda-
mentals which will have equal importance under all conditions.

CONCLUSIONS.

There is a wide variation in the flavor and odor of the milk from
individual normal cows receiving the same feeds.

While silage-tainted. barn air may have some effect on the flavor
and odor of milk, it is of relatively small importance under average
and even under extreme conditions.

The flavor and odor of silage are largely imparted to milk through
the body of the cow.

Silage which is fed one hour before milking is so quickly avsorbed
that its taint is discernible in the milk.

Silage should be fed immediately after milking.

Not over 15 to 25 pounds of corn silage or 15 pounds of legume
silage can be fed twice daily after milking without imparting a dis-
cernible flavor and odor to the milk of cows of similar productive
capacity to those used in this experiment.

Legume silage affects the flavor and odor of milk to a greater
extent than an equal amount of corn silage.

Careful and prompt aeration of the warm milk will permanently
remove silage flavors and odors from slightly tainted milk and
will reduce the degree of more pronounced silage flavors and odors.

Moderate quantities of corn silage fed after milking and the
milk promptly aerated may in some cases actually improve the flavor
of milk that would otherwise have a flat or insipid taste.

While silage odors in the barn air have only a shght effect on the
flavor and odor of milk, it is best to provide adequate ventilation an¢|
exercise other sanitary measures to insure the finest possible flavors.

The feeding of badly decomposed or moldy silage imparts to
milk undesirable flavors. :

Cream from silage-tainted milk possesses and retains silage flavors

and odors to a greater extent than the milk from which it is taken.

Condensed milk made from silage-tainted milk has a less per-
ceptible silage flavor and odor than the milk from which it is made.

LITERATURE CITED.
(1)

1905. How does ensilage flavor get into milk? Jn Hoard’s Dairyman,
v. 36, No. 8, p. 228.

(2) Ergnst, WILLIAM.

1914. Textbook of milk hygiene. p. 149.
(3) FARRINGTON, E. H.

1905. Silage odor in milk. /n Hoard’s Dairyman, v. 36, No. 2, p. 32,
(4) Henry, W. A., and Morrison, F. B.

1917. Feeds and feeding. 16th ed. p, 228.

24

(9)
(6)
(7)

(8)

(9)

(10)

(11)

(12)

BULLETIN 1097 U. S. DEPARTMENT OF AGRICULTURE.

Same, p. 258.
Same, p. 355. >
Kine, F. H.
1897. The construction of silos and the making and handling of silage.
Wis. Agr. Expt. Sta., Bul. No. 59, p. 25-27.
KNISELY, A. L.
1903. Feeding silage to cows. Jn Oregon Agr. Expt. Sta., 15th Ann,
Rpt., p. 4445. ;
MARSHALL, C. H.
1902. Aeration of milk. Mich. Agr. Expt. Sta., Bul. No. 201, p. 216.
RUSSELL, H. L.
1897. Tainted or defective milks, their causes and methods of preven-
tion. Wis.- Agr. Expt. Sta., Bul. No. 62, p. 23-24.
Wott, I. W., and HumpHrey, G. C. ;
1904. Soy bean silage as a food for dairy cows. In Wis. Agr. Expt.
Sta., 21st Ann. Rpt., p. 67-74.
Woopwarp, T. E., and McNutty, J. B.
1914. The making and feeding of silage. Jn U. S. Dept. Agr. Farmers’
Bulletin, No. 578, p, 5 (1914 edition).

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