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STORAGE AND UTILIZATION OF DISTILLERS
AND BREWERS WET GRAINS IN DIETS FOR
LACTATING DAIRY COWS

By
Colin O.L.E. Johnson

A DISSERTATION
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Animal Science

1985

ABSTRACT

STORAGE AND UTILIZATION OF DISTILLERS
AND BREWERS NET GRAINS IN DIETS FOR
LACTATING DAIRY CONS

By
Colin 0.L.E. Johnson

In tests of methods of preserving distillers and brewers wet grains
(OMB and BHG), feeding values for cows were compared.

In Experiment I, DNG were treated with NH3 at 0, 1.57, 3.14, or
5.71% of dry matter (DM), compacted in polyethylene bags, and exposed
to aerobic storage at 15.6, 26.7, or 37.8% for 14 days. Intermediate
and high NH3 reduced temperature increases, mold growth and spoilage,
and improved recoveries of dry matter of the stored grains. Increasing
storage temperatures hastened appearance of mold growth and spoilage
for untreated and low NH3 grains.

In Experiment II, lactating Holstein cows were fed a basal diet
(corn silage, haylage, alfalfa hay, ear corn, and a nfineral-vitamin mix)
supplemented with DHG (13.78% of total DM) treated with NH3, or soybean
meal (58", 10.12% of total DM) for 70 days. Dry matter intakes tended
to be lower for cows fed DNG. Although milk yields and composition did
not differ significantly between treatments, cows fed DNG produced more
milk per kg DM intake than those fed SBM (1.42 vs 1.25). Income over
feed costs was greater for DNG than for SBM.

In Experiment Ia, BN6 were treated with NH3 at 0, 2, or 4% of DM.

Portions of the treated grains were compacted in plastic pails and exposed

Colin 0.L.E. Johnson

to aerobic storage for 3, 7, or 10 days. From the same treated grains,
portions were compacted in polyethylene bags, sealed with twine, and
left to ensile for 7, 14, or 28 days. During aerobic storage, water
soluble carbohydrates increased in grains treated with high NH3 but
decreased for no and low NH3. Mold growth and spoilage were inhibited'
by high NH3. During ensiling, NH3 delayed increases of lactate, presumably
by restricted fermentation. Butyrate was evident only with no and low
NH3. High NH3 was most effective in preserving the wet grains during
ensiling. Other grains lost their original color and had a strong acid
odor.

In Experiment IIa, lactating Holstein cows were fed the basal diet
of II supplemented with either 14.3% SBM, 25.6% fresh BN6, 26.3% ensiled.
BN6, or 14.7% fresh BN6 plus .72% urea for 70 days with daily DM intakes
of 25.2, 21.9, 20.8, and 22.8 kg. Differences for actual milk (29.3,
29.4, 27.7, and 29.0 kg/day) and milk composition were not significant.
Feed efficiencies and income over feed costs were greater for BN6 diets
than for SBM.

0N6 and BN6 can be preserved effectively for 2 wk or more when treated
with NH3 at 3 to 4% of DM. NH3-treated 0N6 and forms of BN6 studied

were equal to and more profitable than SBM as protein supplements.

DEDICATION

To the memory of my beloved mother,

Edna W. Johnson, 1922-1980.

ii

ACKNOWLEDGEMENTS

The author wishes to express his sincere gratitude to
Dr. J.T. Huber for his invaluable assistance, encouragement
and guidance as major professor. Special thanks are also
extended to the members of his guidance committee: Drs. w.
G. Bergen, D.R. Hawkins and F.J. Peabody.

Special thanks also go to all those who aided his
cause, particularly the Department of Animal Science for
their support and facilities provided during his graduate
studies.

Finally, warm thanks to his loving and devoted wife,
Paulette and son, Owen, for their patience and encourage-
ment throughout his graduate studies. In addition, the
author wishes to express his sincere gratitude to his wife

for typing this manuscript.

iii

TABLE OF CONTENTS

Page

LIST OF TABLES O O O O O O O C O O 0 vi
INTRODUCTION . . . . . . . . . . . 1
LITERATURE REVIEW . . . . . . . . . . 3
Distillers Net Grains . . . . . . . 3
Production . . . . . . . . . . 3
Preservation . . . . . . 4
Feeding Value For Ruminants . . . . 8
Lactating Dairy Cattle . . . . . 8

Growing Beef Cattle . . . . . . 10
Finishing Beef Cattle . . . . . 12

Sheep 0 o o o o o o e o 12

Brewers Wet Grains . . . . . . . . 13
Production . . . . . . . . . . 13
Preservation . . . . . . . . 14
Feeding Value For Ruminants . . . . 16
Lactating Dairy Cattle . . . . . 16

Beef Cattle and Sheep . . . . . 18

summary 0 O O O O O O O O O O O 19
MATERIALS AND METHODS . . . . . . . . 21
Distillers Net Grains . . . . . . . 21
Experiment I . . . . . . . . . 21
Aerobic Storage . . . . . . 21
Stability Measurements . . . . . 21
Laboratory Analyses . . . . . . 22
Statistical Analysis . . . . . 22
Experiment II . . . . . . . . . . 23
Lactation Trial . . . . . . . . 23
Laboratory Analyses . . . . . . . 26
Statistical Analysis . . . . . . 26
Brewers Net Grains . . . . . . . . 27
Experiment 18. o o e o o o o o 27
Aerobic and Anaerobic Storage . . 27
Laboratory Analyses . . . . . . 28
Statistical Analysis . . . . . 29
Experiment Ila . . . . . . . . 29
Lactation Trial . . . . . . . 29

iv

Laboratory Analyses .
Statistical Analysis

RESULTS AND DISCUSSION . . .

Distillers Net Grains

Experiment I . . . . .
Stability During Aerobic
Summary . . . . .

Experiment II . . . .
Lactation Trial . . .
Summary . . . . .

Brewers Net Grains . . . .

Experiment Ia . . . .

Stability During Aerobic
Anaerobic Storage . .
Summary 0 o o o 0

Experiment IIa . . . .
Lactation Trial . . .
Summary . . . . .

GENERAL SUMMARY . . . . . .
APPENDICES O O C O O O O
BIBLIOGRAPHY . . . . . .

Storage
and

O

9.

10.

LIST OF TABLES

Chemical composition of corn, distillers
wet grains and soybean meal . . . . .

Pre-treatment milk and milk composition
data (Experiment II) . . . . . . .

Ingredient composition of experimental
diets (Experiment II) . . . . . . .

Ingredient composition of pre-treatment
and experimental diets (Experiment IIa) .

Stage of lactation, milk yield and milk
composition of cows on pre-treatment
(Experiment IIa) . . . . . . . . .

Temperature of distillers wet grains as
affected by added levels of ammonia (NH3)
and days of aerobic exposure at different
storage temperatures . . . . . . .

Dry matter recovery of distillers wet
grains as affected by ammonia treatment
and storage temperature after 14 days of
aerobic exposure . . . . . . . .‘ .

pH of distillers wet grains as affected by
added levels of ammonia (NH3) and days of
exposure at different storage temper-
atures O O O O O O O O O O O 0

Total nitrogen in distillers wet grains as
affected by added levels of ammonia (NH3)
and days of exposure at different storage
temperatures . . . . . . . . . .

Water soluble nitrogen in distillers wet
grains as affected by added levels of
ammonia (NH3) and days of exposure at
different storage temperatures . . . .

vi

Page

24

25

3O

31

35

39

41

43

Table Page

11. Ammonia nitrogen in distillers wet grains
as affected by added levels of ammonia
(NH3) and days of exposure at different
storage temperatures . . . . . . . 44

12. Chemical composition of experimental diets
(Experiment II) o o e e e o o o o 47

13. Dry matter intake, milk yields and persis—
tencies of cows fed the experimental diets
(Experiment II) . . . . . . . . . 48

14. Milk composition, feed efficiency and
average daily gain of cows fed the experi-
mental diets (Experiment II) . . . . . 50

15. Economic evaluation of the experimental
diets (Experiment II) . . . . . . . S1

16. Changes in temperature and dry matter of
brewers wet grains as affected by ammonia
treatment and days of aerobic exposure . 54

17. Dry matter of brewers wet grains as
affected by ammonia (NH3) treatment and
days of ensiling . . . . . . . . . 56

18. pH of brewers wet grains as affected by
ammonia (NH3) treatment and days of
aerobic exposure or ensiling . . . . . 58

19. Lactic acid in brewers wet grains as
affected by ammonia (NH3) treatment and
days of aerobic exposure or ensiling . . 6O

20. Residual water soluble carbohydrates in
brewers wet grains as affected by ammonia
(NH3) treatment and days of aerobic
exposure or ensiling . . . . . . . 62

21. Acetic acid in brewers wet grains as
affected by ammonia (NH3) treatment and
days of aerobic exposure or ensiling . . 64

22. Total nitrogen in brewers wet grains as

affected by ammonia (NH3) treatment and
days of aerobic exposure or ensiling . . 66

vii

Table Page

23. Water soluble nitrogen in brewers wet
grains as affected by ammonia (NH3) treat-
ment and days of aerobic exposure or
enSj-ling O O O O O O O O O O O 68

24. Ammonia nitrogen in brewers wet grains as
affected by ammonia (NHB) treatment and
days of aerobic exposure or ensiling . . 69

25. Chemical composition of experimental diets
(Experiment IIa) . . . . . . . . . 72

26. Chemical composition of fresh and ensiled
brewers wet grains during the experimented
periOd O O O O O O O O O O O O 73

27. Undegraded and water soluble nitrogen in
the experimental diets (Experiment IIa) . 75

28. Dry matter intake of cows fed the experi-
mental diets (Experiment IIa) . . . . 77

29. Milk yields, persistencies and milk com-
position of cows fed the different protein
supplements (Experiment IIa) . . . . . 78

50. Body weight gains and feed efficiencies of
.cows fed the different protein supplements
(Experiment IIa) . . . . . . . . . 80

31. Influence of protein supplement on income
over feed costs of experimental diets
(Experiment IIa) . . . . . . . . . 81

_Appendix Tables
1. Butyric acid in brewers wet grains as
affected by ammonia treatment and days of
aepobic exposure or ensiling (Experiment
Ia O O O O O O O O O O O I O 86

2. An example of an analysis of variance with
orthogonal polynomial contrasts . . . . 87

viii

INTRODUCTION

Large quatities of distillers and brewers wet grains
are becoming available from the production of alcohol by
distilleries, breweries and gasohol plants. Traditionally,
these by-products have been utilized in the dried form as
feed ingredients for livestock. However, increased costs
associated with drying the by-product has caused renewed
interest in feeding these feedstuffs in their wet form. On
a dry matter basis, the nutritional value of the wet grains
is comparable to the dried grains. A key problem in the
utilization of these by-products, however, is the rapid
molding and spoilage after production, especially during
warm weather.

Much of the research with distillers and brewers by-
products have focused on protein resistant to ruminal
microbial degradation. From available research, it appears
that these by-product feeds are more resistant to microbial
degradation in the rumen than the commonly fed oilseed meal
from soybeans, cottonseed and linseed. Thus, protein of low
rumen degradability will result in more post ruminal diges-
tion and usually enhance net amino acid uptake by the host
animal. In high producing dairy cows and rapidly growing
beef, microbial protein is insufficient to meet protein

needs for achieving maximum performance; thus, an increase

in protein which will not degrade in the rumen, but will be

broken down postruminally is often benificial.

Presently, nonprotein nitrogen (NPN) is well accepted
in rations for ruminants. Of the total NPN presently
incorporated into ruminant rations, approximately 90% is
urea. However, per unit of nitrogen, the cost of ammonia
(anhydrous form) ranges from 60 to 70% of the cost of urea.
In addition to ammonia furnishing nitrogen for microbial
synthesis in the rumen, ammonia treatment has raised energy
availability of low quality roughages, increased the true
protein of silages and retarded heating and molding of
certain feeds, especially during high ambient temperatures.

The research associated with this thesis was designed
to ascertain:

1) The influence of added levels of ammonia, exposure
time, and storage temperature on the aerobic stability
of distillers wet grains (DNG).

2) The value of ammonia-treated DNG as a protein supple-
ment for lactating dairy cows, and return over feed
costs of DNG relative to soybean meal.

3) The influence of added levels of ammonia on the aerobic
and anaerobic stability of brewers wet grains (BN6).

4) The comparative value of fresh BN6, fresh BN6 + urea,
ensiled BNG and soybean meal as protein supplements
for lactating dairy cows for maintaining milk yields

and return over feed costs.

REVIEW OF LITERATURE

This review will examine the information currently
available on the preservation of distillers and brewers
wet grains, and also evaluate their feeding value in diets

of ruminants, principally dairy and beef cattle and sheep.
Distilleps Net Grains

Production

In the conventional beverage distillery, corn is the
primary grain used in the distillation process. Grains
are ground, slurried with water and cooked to gelatinize
starch. The resulting product is then cooled to a temper-
ature suitable for fermentation, innoculated with yeast
and allowed to ferment for three to five days. For the
commonly used yeast strains, the Optimum fermentation
conditions are 27 to 35°C at a pH of 3.0 to 5.0 (NAP,
1981). During the fermentation process, starch is converted
to alcohol and carbon dioxide. Starch comprises two-thirds
of the original corn grain, and therefore, the concen-
tration of nutrients remaining in the by-products is
increased three-fold. Whole stillage is the by-product
remaining after the distillation of alcohol. This product
typically contains 5 to 14% solids. Grains can then be

separated from the whole stillage by screening, pressing

4
or centrifugation. The result is isolation of distillers
wet grains (DWG) which contains 25-35% solids (NAP, 1981).
Preservation

A key problem in utilization of DWG is rapid molding
and spoilage when exposed to air, especially during warm
weather. Traditionally, the wet grains are dried after
separation from whole stillage in order to facilitate long
term storage and movement through normal feed channels.
However, with increased petroleum prices the cost of drying
the wet grains also increases. Consequently, large distill-
eries as well as operators of farm sized stills have become
interested in alternative methods of usage.

Immediately after separation from whole stillage,
fresh DWG is 71°C, contains 65-75% moisture, and has a pH
to 3.0 to 4.0. (Klopfenstein and Abrams, 1981; NAP, 1981).
Without any preservatives this by-product has a shelf life
of approximately 2 to 3 days at summer temperatures (Waller
gt'al; 1982) and 6 to 8 days or longer in cold weather
(NAP, 1981). In spite of the low initial pH attempts to
store the wet grains for longer than 2 to 3 days in the
summer months have resulted in excessive spoilage, mold
growth and dry matter losses (Rakshit and Voelker, 1981;
Waller 23 al., 1982). Most workers conclude that a pH 4.2
is the critical value at which silages are well-preserved
(Carpintero §£,§l., 1969). However, for high moisture
material such as distillers wet grains, it would appear

that a lower critical pH is necessary for acceptable

5
preservation. Nhittenbury gi‘al., (1967) reported that

Clostridia, implicated in DWG deterioration, can tolerate
high concentrations of organic acids and hydrogen ions
under very wet conditions. Moreover, Zimmer (1971) observed
an inverse relationship between dry matter losses associated
with the storage of high moisture material and the degree

of air-tightness achieved.

Treating fresh DWG with 1% propionic acid (on a dry
matter basis) has eliminated mold growth and reduced dry
matter losses over a seven-week storage period (Rakshit
and Voelker, 1981; Schingoethe §3_§l., 1983). Since mold
growth was eliminated by propionic acid treatment, it seems
likely that the destruction of organic acids, especially
propionate, by other microorganisms is a factor which allows
mold growth in untreated-wet grains. Similar results were
reported for high moisture grains (Jones and.Stevenson,
1970), grass silage (Daniel §£_§;., 1970) and haylages
(Thomas, 1978) treated with propionic acid. In addition to
eliminating mold growth and reducing dry matter losses,
propionic acid also reduced temperatures in fresh DWG
exposed to air (Rakshit and Voelker, 1981; Diallo g£,§;.,
1984). Diallo g: 3;. (1984) reported a linear increase in
days (16 to 19) to reach 10°C above ambient temperature
with increasing levels of added propionic acid, when concen-
trations of propionate ranged from .3 to .6% of the dry
matter.

There is little information available on alkali

6

treatment of fresh DNG. However, in the study reported by
Abrams 23,§l. (1983), fresh DNG averaging 31.1% dry matter
(DM) were treated with O, 1.0, 2.0 or 3.0g calcium hydr-
oxide/100g DM or with O, .309, .618 or .926g ammonium hydr-
oxide/100g DM. In addition, the wet grains were also treated
with O or 5.0g sugar/100g DM and 0 or .3g live microbial
silage inoculant (Streptococcus and Lactobacillus)/100g DM.
The treated or untreated material were packed tightly in
laboratory silos (.946 liter glass jars), sealed and allowed
to ensile for 21 days at 39°C. Results from this study
showed that no fermentation occurred in the absence of
alkali. Such an observation was expected in view of the low
pH of fresh DWG (NAP, 1981). However, alkali additions
resulted in a butyric acid fermentation with small amounts
of acetate, propionate and lactate produced, thereby
suggesting the presence of saccharolytic clostridial
activity (Nhittenbury §§_gl., 1967). In addition, sugar
addition resulted in delayed decreases in pH for ammonium
hydroxide treated grains. According to Rydin gt El- (1956),
added sugar does not always pass through the process of
lactic acid fermentation, but may also be transformed into
butyric acid, acetic acid, etc. This results in a delayed
decrease in pH, thus providing a favorable medium for the
growth of putrefactive clostridia (Nhittenbury, 1968).
Preliminary observations of ammonia-treated DWG exposed to
aerobic storage for 9 days at various temperatures,

indicated that 4.5% ammonia (on dry matter basis) was

7

effective in retarding temperature increase, spoilage and
dry matter losses (Waller 23’§;., 1982; Huber fig al., 1983).
In the study reported by Diallo g£,§l. (1984), DWG were
treated, on a dry matter basis, with .3, .4, .5 or .6%
ammonia and subsequently exposed to air for 24 days. Days

to reach 10°C above ambient temperature increased with
increased ammonia, but were lower than for untreated grains.
The ineffectiveness of ammonia in preventing temperature
rises was due to the low levels of ammonia applied. Other
measures of stability were not reported.

Formaldehyde (F) applied at 2 to 4% by weight of the
dry protein content of DWG also prevented spoilage during
a 28-day ensiling period (Waller g3.al., 1982). Lower F
levels (.3 to .6% of the dry matter) were also effective
in preventing temperature increases of DNG exposed to air
for 24 days (Diallo 33 al., 1984). A mixture of sodium
diacetate and sorbic acid (72% sodium diacetate and 28%
sorbic acid) applied at .3 to .6% of the dry matter also
prevented increased temperatures of DWG exposed to air for
24 days (Diallo 233;” 1984).

Field observations of ethanol plants that fail to
remove all the ethanol from the grains during the distil-
lation process indicate that the storage life of DNG with
at least 0.7% ethanol is longer than that of the wet grains
devoid of ethanol (Waller 23 al., 1982).

Feeding Value For Ruminants:

Typical chemical composition valuesfor corn, DWG and
soybean meal are shown in Table 1. From these values, it
becomes apparent that an energy source (corn) has been
converted to a protein source with higher concentrations
of acid detergent fiber, fat, calcium and phosphorus. A
comparison of DNG with soybean meal reveals lower protein,
but higher concentrations of fiber, fat, phosphorus and
total digestible nutrients (TDN) in the by-product. The
lysine content of protein in distillers grains, however,
is less than half that of soy protein (Satter, 1983). On
the other hand, methionine supply from distillers grains
is distinctly superior to that from soybean meal (Satter,
1983).

The feeding value of DNG for ruminants is based
primarily on its ability to resist microbial degradation
in the rumen. This resistance is probably due to zein, the
major protein in corn, and its by-products, which are not
readily degraded by rumen microorganisms (McDonald, 1954).
However, under certain feeding regimens depending on stage
and type of production, microbial nitrogen is insufficient
to optimally furnish the protein needs of the animal. In
order to achieve maximum performance, post ruminal diges-
tion of some dietary protein is required (Orskov, 1978;
Huber and Kung, 1981; Owens and Bergen, 1983).

Lactating Dairy Cattle

There is limited information on feeding DNG to dairy

9

Table 1. Chemical composition of corn, distillers wet
grains (DWG) and soybean meal (SBM)a

 

 

Item Corn .DWG SBM
Dry matter (%) 89 25 90
Crude protein (%) 10 30.6 48.9
Acid detergent fiber (%) 1.4 - 18 7.0
Fat (%) 4.4 8.0 5.2
Calcium (%) .02 .16 .28
Phosphorus (%) .30 .79 .75
TDN (%) 88.0 .84.0 81.0

 

aAll composition values other than TDN were taken from
Telplan Program 31 Form 3 (MSU, 1981); TDN values were
taken from NRC (1978).
cattle. In the study reported by Schingoethe gt_§l. (1983),
a switch-back design consisting of three-4 wk. periods was
used to evaluate the feeding value of DWG for lactating
dairy cows. In addition to being fed corn silage ad
libitum and 3.2 kg alfalfa hay daily, cows were fed either
a control concentrate (18.6% crude protein) consisting of
corn, oats and soybean meal at 1 kg/2.5 kg milk produced,
or 13.6 kg distillers wet grains (22% of total ration dry
matter) and a 10.9% crude protein concentrate mix of corn
and cats at 1 kg/2.5 kg milk produced in excess of 11 kg
milk daily. Cows averaged 12 wks. postpartum at the start
of the experimental period. Results from this study

revealed no significant differences in milk or milk

10

composition between the two treatment groups. Also, total
dry matter consumption and body weight gains were similiar
for both groups. Apart from the higher concentration of
rumen propionate for cows fed the DWG, rumen volatile fatty
acids, pH and ammonia were similar for both groups. The
higher concentration of rumen propionate (24.5 vs. 21.9
moles/100 moles VFA) was probably due to miscalculation of
the energy value of distillers wet grains, resulting in
more total concentrate fed in the diet.
EggginggBeef Cattle

Optimum use of preformed protein and maximum use of
nonprotein nitrogen have been the goals of ruminant nutri-
tionists and cattle feeders for many years. As previously
mentioned, distillers grains are more resistant to micro-
bial degradation in the rumen than are the commonly fed
oilseed meals from soybean, cottonseed and linseed (Satter
g£_al., 1977). However, when fed as the sole source of
supplemental protein, lack of degradability of the protein
in the rumen can result in a deficiency of rumen ammonia
for microbial protein synthesis (Taminga, 1979). Since
ammonia is the central compound for protein synthesis in
the rumen (Huber and Kung, 1981), it seems possible that
ammonia can be provided in the rumen by replacing some of
the nitrogen in DWG with urea.

This concept was demonstrated in a cattle growth trial
reported by DeHaan gt,§l. (1982), where urea provided 50%

of the supplemental protein equivalent in rations

11

supplemented with soybean meal or DNG. The control ration

of corn silage and corn cobs was supplemented with only
urea nitrogen. Daily gains were highest for steers fed DNG
and lowest for the urea control. The same trend was observed
for feed efficiency. Protein efficiency, defined as gain '
above the urea control, divided by amount of supplemental
protein intake, was higher for steers on the DWG diet.

In a similar growth trial with steers (Abrams 2: al.,
1983), basal diets consisting of corn silage and corn cobs,
were supplemented with the following protein supplements:
(1) 100% urea; (2) 50, 75 or 100% soybean meal (SBM);

(3) 30, 40 or 50% DNG; or (4) 30, 40 or 50% calcium hydr-
oxide ensiled distillers wet grains (EDNG), with urea
making up the difference. Preformed protein supplements
were combined with the urea supplement to provide incre-
mental levels of test protein, while dietary protein level
(11.5%) remained constant. Except for lower gains by steers
on the 100% urea supplemented diet, no differences in gains
among the steers fed DNG, SBM or EDWG diets were demon—
strated. Feed efficiencies followed the same trend. Because
the protein in DWG or EDWG was fed one-half the level of
SBM protein, steers fed the urea supplemented DNG demon-
strated greater protein efficiency than those fed urea
supplemented SBM or EDWG. Urea supplemented EDWG was
intermediate, probably due to the increased solubilization

of nitrogen during ensiling. Assigning a value of 100% to

12

SBM, the relative values of DNG and calcium hydroxide EDNG
were 282% and 142%, respectively.
Flagshing Beef Cattle

Once feeder cattle approach the finishing stage, the
ability of the rumen to provide protein exceeds the animal's
need (NRC, 1984); thus, research in feeding Due to finishing
cattle for its ruminal undegradable nature would not be
useful. However, feedlot performance, as measured by feed
efficiency and daily gains, was as good or better when fed
diets supplemented with DWG than when fed corn-based diets
(Farlin, 1981; Firkins 33 al., 1985). Best performances
were obtained with 42.5 to 50.0% of the dietary dry matter
as DNG. The fact that DNG contain little or no starch and
a higher fiber content suggests that ruminal pH may not
have been decreased as much as with diets based on higher
amounts of corn, thereby resulting in the improved feedlot
performance reported in these trials. However, results from
these trials suggest that DWG can be utilized effectively
as an energy source by feedlot cattle at levels as high as

50% of dietary dry matter.

Sheep
Studies conducted with sheep in which DNG provided

supplementary nitrogen have been limited. However, Abrams
2£.§l- (1983) reported that lambs gained faster and more
efficiently when DWG and urea provided supplemental

nitrogen than when soybean meal and urea or urea alone

13

were protein supplements. Protein efficiencies (gain above
the urea control, divided by amount of supplemental protein
intake) were also higher for the distillers grain-urea
combination (fresh or ensiled with calcium hydroxide). In
another study with similar treatment combinations, dry
matter intake and digestibility were higher when soybean
meal provided the supplemental nitrogen. Generally, if
nitrogen were limiting the rumen fermentation, then volun-
tary feed intake and digestibility would be depressed. From
the data reported, rumen ammonia levels at 4 and 6 hours
after feeding were lower for lambs receiving DNG compared

to those receiving soybean meal.
Brewers Wet Grains

Production

No two breweries produce beer in exactly the same
manner. Hence, variation exist both in processing and raw
materials used. Nevertheless, the basic cereals used in
U.S. breweries today are barley and either corn or rice.

In the brewing process, the cereals are first mashed
under carefully controlled conditions in order to convert
the starch into more soluble sugars. After mashing is
complete, the material is separated into liquid and solid
fractions by extraction or filtration. The liquid portion
(called "wort") containing the fermentable sugars is added
to brew kettles together with hops to produce beer or ale.

Brewers wet grains (BWG) is the solid fraction remaining

14
after the "wort" is removed. This fraction may either be
fed to animals without further processing or dried to
produce brewers dried grains (BDG).
Pgeservation

A practical concern with the utilization of BN6 is
their keeping quality during storage and subsequent exposure
to air, especially during warm weather. Drying produces a
stable product; however, due to costs associated with
drying, alternative methods are being investigated.

One method of preservation that has been and is
currently being investigated is the application of organic
chemicals to the wet grains to prevent spoilage during
storage and exposure to air. Chemicals most commonly used
are formic acid, propionic acid, formaldehyde and para-
formaldehyde. Effects of these preservatives are well
documented for high moisture crops (Thomas, 1978) and
grains (Jones and Stevenson, 1970; Jones, 1970).

Using test-tube silos (160 ml), Allen and Stevenson
(1975) showed that 0.50 and 0.75% formic acid or 0.75%
formic-propionic acid mixture, applied on a fresh weight
basis, were effective in preserving fresh BN6 during 18
days of ensiling. Lower levels resulted in poorly preserved
grains containing high levels of acetic acid, butyric acid
and ammoniacal nitrogen. Another study (Oleas, 1977) using
250-liter barrels lined with polyvinyl as silos, showed
that 2% propionic acid or 1.4% formic acid plus 0.1% para-

formaldehyde were effective in preserving fresh BN6 during

15
60 days of ensiling. Ethanol and lactic acid were the main
fermentation products. In that study, the barrels were
sealed with plastic bags filled with water.

Storing untreated BN6 in uncovered piles has resulted
in extensive mold growth, discoloration and dry matter
losses (Allen g£_al., 1975). However, a 0.40% formic-
propionic acid mixture was effective in reducing all aspects
of deterioration during a 14-day exposure period. Formic or
propionic acid applied at the same level were effective in
reducing subsurface deterioration, but were unable to
reduce surface spoilage. Sodium chloride, applied at 1.0%
of the fresh weight, reduced spoilage in BN6 exposed to
air (Chase, 1977).

Another method investigated is the application of
fermentation stimulants in the form of carbohydrate sources
or lactic acid forming bacteria to wet grains. Interest in
these methods stems from the fact that most fermentable
carbohydrates, which are substrates for lactic acid
production, are removed from the grains during brewing.
Molasses, the most widely used carbohydrate source, has
successfully improved preservation of high moisture crops
harvested with levels of low soluble carbohydrates
(Dijkstra, 1958; Carpintero 23 al., 1969; McCarrick, 1969).
However, when used with BN6, no improvement over untreated
wet grains was demonstrated under aerobic or anaerobic
conditions (Allen and Stevenson, 1975; Allen 23 §;., 1975;

Oleas, 1977). Negative results were also reported for

16
lactic acid cultures (Oleas, 1977) with no significant

improvement over untreated wet grains. Schoch (1957),
however, reduced dry matter losses in BN6 ensiled with 10
to 15% dried apple residue.
FeedinggValue For Ruminants

As with distillers wet grains, the feeding value of
BN6 for ruminants is enhanced because protein in the grain
resists microbial degradation in the rumen and is available
for digestion and absoption in the small intestine. Based
on ip,vi££g and ip,1ivo estimates, the protein in BN6 was
much more resistant to microbial degradation than that of
soybean meal, although not quite as resistant as that of
the dried grains (Satter and Nhitlow, 1977; Klopfenstein
gt §;., 1977; Santos 23 al., 1984). Apart from its high
protein content (23-39%) and value, the high fiber (23-62%
acid detergent) and energy (66-78% TDN) in BN6 make it a
valuable component in ruminant rations.
Lactating Dairy Cattle

There is limited information on the relative feeding
value of BN6 compared to the dried grains in diets for
lactating dairy cows. However, the studies by Conrad and
Rogers (1977) suggest that BN6 are used more efficiently
for milk production than the dried grains. Although dry
matter intake was depressed when wet grains were fed at
20% of total dietary dry matter, milk production was
similar to cows receiving the same dry matter from BDG. In
the same report cows fed rewetted BDG at 20% of total

dietary dry matter also showed depressed feed intakes, but

17

similar milk production to the group receiving dried grains,
suggesting that the moisture in wet grains could limit
intake. This is supported by the findings of Davis 22.2l'
(1983) who observed a depression in dry matter intake by
1.5, 2.6 and 4.9 kg/cow/day when BN6 containing 31% dry
matter supplied 20, 30 or 40% of total dietary dry matter.
Murdock gt_al. (1981), using cows in the first 140
days of lactation, found no differences in milk production,
milk composition, rumen volatile fatty acids or rumen pH
when BN6 (25.6% dry matter) replaced all the supplemental
soybean meal and barley in corn silage-alfalfa hay based
diets. Brewers wet grains comprised 15 and 30% of total
dietary dry matter. The characteristic depression in intake
with high levels of BN6 in the diet was not observed in
this study. However, with cows past peak lactation, Davis
gt gl. (1983) observed depressions in both milk production
and dry matter intake when BN6 replaced soybean meal and
comprised greater than 20% of total dietary dry matter in
corn silage-based diets. Surprisingly, cows also lost
weight on the diets supplemented with BNG. Weight losses
were progressively greater with increasing levels of BN6.
No change in body weight was observed for cows on soybean
meal supplemented diets. Using cows in a similar stage of
lactation, Santos gi‘gl. (1984) demonstrated greater
absorption of total amino acids from BN6 diets than on
soybean meal diets. Each test protein supplied approxi-

mately 50% of the total dietary protein in corn

18

silage-alfalfa hay based diets. Although milk production
was not measured, the results of this study and those
reported by Murdock pp Q. (1981) and Davis 33 3;. (1983)
suggest that the feeding of a protein source that is
relatively undegradable in the rumen will not always
improve milk production.

Beef Cattle and Sheep

Unlike distillers wet grains, there is limited infor-
mation available on the feeding value of BN6 for beef
cattle and sheep. The study reported by Linton (1977),
comparing the relative feeding value of fresh BN6 to stored
(untreated) BN6 in diets for growing steers, showed no
significant differences in cumulative feed intake, weight
gains or feed efficiency when fresh or stored grains
comprised 25 or 50% of total dietary dry matter. However,
'the tendency was for better animal performance with the
lower level of BN6. Except for a vitamin-mineral supple-
ment (0.23 kg/head/day), corn silage was the only other
ingredient in the diets fed.

Available evidence on the feeding value of BN6 for
sheep is lacking. However, in the report by Satter and
Nhitlow (1977), sheep were used as models to determine
amino acid flow to the intestine from diets in which the
major portion of dietary test protein (nitrogen) was
provided by Starea (commercial product composed primarily
of urea and starch), soybean meal, dried brewers grains

or wet brewers grains. The diets were formulated to be

19

isofermentable and to allow adequate ammonia production

for maximum microbial growth rates. Results from the study
revealed that a larger portion of the brewers grain diets
were digested post-ruminally, with the dried grains higher
than the wet grains. The flow of amino acids to the intes-.
tine was about 30% higher with the brewers grains than
other diets. Similar results have been reported by Santos

.22.§l- (1984) with growing steers.

Summary

Both distillers and brewers wet grains have desirable
characteristics that make them suitable components in
ruminant rations. However, a practical concern with their
utilization is rapid molding and spoilage after production,
especially during exposure to air and in warm weather. In
order to prolong their keeping quality until they can be
effectively incorporated into ruminant diets, several
additives such as organic acids, carbohydrates and lactic
acid bacteria have been added to wet grains. The effective-
ness of organic acids in reducing or preventing spoilage
was shown to vary with the level of application and the
mixtures used. Carbohydrates and lactic acid bacteria were
less effective than organic acids in preventing spoilage.

There is limited information on the relative feeding
value of distillers wet grains in diets of dairy cattle.
However, available information from beef cattle and sheep

studies suggest an equal feeding value to soybean meal

20

when a combination of urea and distillers wet grains
supplied the supplemental nitrogen.

Unlike distillers wet grains, few studies have been
reported on the relative feeding value of brewers wet
grains for beef cattle and sheep. Nith dairy cattle, some
studies indicate an equal feeding value to soybean meal
and dried brewers grains, while others indicate a depres-
sion in animal performance when fed at more than 20% of
dietary dry matter.

Our studies were designed to test various methods of
preserving distillers and brewers wet grains, and to deter-

mine their feeding value for dairy cows resulting from these

methods.

MATERIALS AND METHODS
Distillers Net Grains
Experiment I. Aerobic Storagg

Fresh distillers wet grains (31.2% dry matter),
provided by an ethanol producing plant in Michigan, was
apportioned into four-50 kg batches to facilitate mixing
and application of treatments in a stainless steel feed
mixer equipped with a horizontal ribbon mixer. Each batch
was treated on a dry matter basis with 0, 1.57, 3.14 or
4.71% ammonia (NH3) equivalent from ammonium hydroxide
(29.4% NH3)' After each treatment, temperatures of the
grains were taken with a 20.32cm. temperature probe and
samples representative of day zero were frozen immediately.
Thereafter, duplicate samples (5.5 kg each) were compacted
in double-lined polyethylene bags and exposed to aerobic
storage at 15.6, 26.7 or 37.800 for 4, 9 and 14 days. For
the low and intermediate temperatures, constant temper-
atures were maintained in egg-holding rooms, and a forced-
draft incubator was used for the high temperature storage.
Stability Measurements

Changes in temperature and appearance of visible mold

in the stored grains were monitored daily. Changes in pH,

21

22
dry matter, total nitrogen, water soluble nitrogen and
ammonia nitrogen were also determined as measures of
stability.

To faciliate calculation of dry matter recovery, bags
were weighed before and after removal of samples for labo-
ratory analyses. All samples were frozen at - 10°C until
analyzed.

Laboratory Analyses

Samples were thawed and ground before analysis in a
Hobart chopper. Dry matter was determined on 40g portions
of the ground samples by drying in a forced-air oven at
65°C for 48 hours. Aliquots of the ground samples were also
used for the determination of total nitrogen by macro-
Kjeldahl. Water soluble nitrogen was determined by macro-
Kjeldahl on the supernatant after 15g of the ground sample
was homogenized with 100 ml distilled water for 2 min. in
a Sorvall Omnimixer, strained through four layers of cheese-
cloth and centrifuged at 27,000x g for 10 min. Ammonia
nitrogen was determined on the supernatant by methods
described by Chaney and Marbach (1965). The pH was deter-
mined on the water extract before centrifugation by using
a standard glass electrode connected to a pH meter.
Statistical Analysis

Statistical analysis of the data was according to
procedures described by Genstat V (Lawes Agricultural
Trust, 1980) and involved partitioning of the main effects

and interactions in the analysis of variance into

23
orthogonal polynomial contrasts.
Experiment II. Lactation Trial

Prior to treatment, 20 lactating Holstein cows were
fed a complete ration (15% crude protein) consisting of
corn silage, alfalfa hay, high moisture ear corn, soybean
meal and a vitamin-mineral mix for 14 days. Cows were
subsequently blocked for pretreatment milk yield and
randomly assigned to one of two treatments for 70 days.
Pretreatment milk and milk composition data are in Table 2.
At the start of the 70 day trial, cows averaged 79 days in
lactation.

Treatments consisted of furnishing the protein supple-
ment in a typical midwestern ration for lactating cows as
soybean meal or ammonia (NH3)-treated distillers wet grains
(Table 3). Diets were formulated to be isonitrogenous
(15% or) and isocaloric (1.65 Mcal/kg dry matter).
Distillers wet grains was supplied biweekly from the same
source as in Experiment 1. Upon arrival, the wet grains
were treated on a dry matter basis with 4-5% ammonia
equivalent from aqua-ammonia (25%“NH3) mixed in a feed
truck equipped with scales and horizontal ribbon mixers,
and stored on the concrete floor of a hay barn.

Diets were fed twice daily with a weekly adjustment
of the amounts fed to allow for 5-10% refusal. Feeds and
feed ingredients were sampled three times per week, and
weekly composites frozen at - 10°C until analyzed. Feed

intakes and milk production were monitored daily, and

24

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26

a daily composite milk sample (AM and PM) was taken for
composition analysis biweekly. Cows were weighed for 2
consecutive days during the second and last week of treat-
ment to determine changes in body weight.
Laboratory Analyses

pH, dry matter and total nitrogen determinations of
feeds and feed ingredients were as in Experiment 1. Acid
detergent fiber (ADP), acid detergent insoluble nitrogen
(ADIN) and neutral detergent fiber (NDF) were analyzed
according to methods described by Goering and Van Soest
(1970). An alpha-amylase preparation was used during NDF
analysis to remove interfering carbohydrates (Robertson
and Van Soest, 1981). Milk samples were analyzed for fat,
protein, lactose and total solids by infrared analysis
(A.0.A.C., 1975).
Statistical Analysis

Data were analyzed as a randomized complete block
design utilizing Genstat V (Lawes Agricultural Trust, 1980).
Treatment means were adjusted by covariance analysis for

pretreatment measurements.

27

Brewers Net Grains

The brewers wet grains (BN6) used in the following
experiments were supplied weekly by Murphy Products Company,
Inc., Detroit Michigan.

Experiment Ia. Aerobic and Anaerobic Storage

Upon arrival, fresh BN6 (22% dry matter) was appor-
tioned into three-59 kg batches to facilitate mixing and
application of treatments in a stainless-steel feed mixer
(as used in the DN6 stability study). Temperatures of the
wet grains were recorded before and immediately after each
treatment using the afore-mentioned temperature probes. Each
batch was treated on a dry matter basis with O, 2 or 4%
ammonia (NH3) equivalent from ammonium hydroxide (29.4%
NH3)' After each treatment, samples respresentative of day
zero were frozen immediately to - 5°C.

For the aerobic study, approximately 3 kg portions of
the treated material were compacted in 3 1 plastic pails
that were exposed to air at room temperature for 3, 7 or
10 days. Temperature probes were positioned at the 1.5 1
level in each pail to monitor daily changes in temperature
of the treated grains. Appearance of visible mold was also
monitored on a daily basis.

For the anaerobic study, approximately 5.5 kg portions
of the treated material were compacted in double-lined
polyethylene bags, sealed with twine, packed into a 100 l
garbage container and left to ensile at room temperature

for 7, 14 or 28 days. In both studies, 2 replicates were

28

made for each treatment and period of storage.

At the specified time intervals, replicates were
removed from storage and analyzed immediately for pH, dry
matter and total nitrogen. Water soluble extracts were also
prepared. For the aerobic samples, all surface mold was
discarded and the remaining portion was thoroughly mixed
before sampling.

Laboratory Analyses

Determination of pH, dry matter and nitrogen fractions
were as described for the DN6 experiments. Nater soluble
carbohydrates and lactic acid were determined on the
supernatant (as prepared for water soluble nitrogen)
according to methods described by Dubois 23 gl. (1956) and
Barker and Summerson (1941), respectively. Concentrations
of volatile fatty acids in the samples were determined on
the supernatant by gas chromatography. Prior to injection,
1 ml of supernatant was acidified with 0.2 ml of 88% formic
acid. Injection volume was 2.5 ul. The column was glass
(76.2 cm long with an internal deameter of 4 mm) packed
with carbopack C and maintained at 120°C. Inlet port and
detector temperatures were maintained at 20000. A hydrogen
flame ionization detector was used, and nitrogen (50 ml/
min) was the carrier gas. Peak areas were measured via an
electronic integrator and concentrations in samples
calculated by comparing to peak areas of standard mixtures

of volatile fatty acids.

29

Statistical Analysis

Data were analyzed as a 2-factor completely randomized
design (Gill, 1978a) with the partitioning of the main
effects and interactions of the analysis of variance into
orthogonal polynomial contrasts using Genstat V (Lawes
Agricultural Trust, 1980).
Experiment IIa. Lactation Trial

Thirty-six.Holstein cows in early to mid-lactation
were originally fed a pretreatment standardization diet
(15% crude protein) consisting of corn silage, haylage,
high moisture ear corn, soybean meal and a vitamin-mineral
premix in a total mixed ration for 2 weeks. Cows were
subsequently blocked for pretreatment milk production and
randomly assigned to one of four treatments. However, due
to the rapid decline in milk production in the first week
of treatment for cows on BNG diets, all cows were restan-
dardized for an additional 2 weeks. During this period,
fresh and ensiled BNG plus urea were gradually increased
in three pretreatment diets (Table 4) which were fed in
sequential order for 7, 3 and 4 days. Cows were subse-
quently blocked for pretreatment milk production (latter
2 weeks) and randomly assigned to one of four treatments
for 70 days. Pretreatment milk and milk composition data
are in Table 5.

To the basal diet consisting of corn silage, alfalfa
hay, high moisture ear corn and vitamin-mineral premix

(Table 4) one of the following protein supplements was

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32

added at the percents listed: soybean meal (SBM), 14.3%;
fresh brewers wet grains (EBNG), 25.6%; ensiled brewers
wet grains (EBNG), 26.3%; or 14.7% FBNG plus .72% urea
(FBNGU). Diets were formulated to be isonitrogenous (15.5%
CP) and isocaloric (1.6 Mcal/kg dry matter).

There were two sources of ensiled brewers wet grains.
One was ensiled in a fabricated-box structure and fermented
for 3 months before feeding. The other was ensiled in a
commercial plastic bag silo (Ag-bag) and fermented for 1
month before feeding. Most of the EBNG in the box was used
up by the second week of the experimental period. The FBNG
was delivered weekly and stored on the concrete floor of a
horizontal silo.

Diets were fed twice daily, and the amounts fed
adjusted weekly to allow 5-10% refusal. Feed intakes and
milk yields were monitored daily. A daily composite milk
sample (AM and PM) was taken biweekly for analysis of fat
protein, lactose and total solids. Cows were weighed on 2
consecutive days during the second and last week of the
experimental period to determine changes in body weight.
Complete diets were sampled every other day and weekly
composites frozen until analyzed. Fresh and ensiled brewers
wet grains were also sampled on alternate days and analyzed
individually rather than as composites in order to deter-
mine day to day variation in composition associated with
exposure to air. Other feed ingredients were sampled

biweekly and monthly composites frozen until analyzed.

33

Laboratory Analyggg

Feeds, feed ingredients and milk samples were analyzed
as previously described. Ash was determined on air dried
samples by standard A.0.A.C. (1984) methods. Rumen unde-
gradable dietary nitrogen was determined on air dried feed .
samples according to procedures described by Poos 23,§l.
(1979), which employed a proteolytic enzyme degradation
system.
Statistical Analysis

Animal performance data were analyzed as a split-block
repeat-measure design (Gill, 1978b) using Genstat V (Lawes
Agricultural Trust, 1980). Treatment means for milk produc-
tion and milk composition were adjusted by covariance
analysis for stage of lactation and other related pretreat-
ment measurements. Bonferroni contrasts (Gill, 1978a) were
used to compare differences between dietary means, and a
combination of Bonferroni and orthogonal polynomial
contrasts (Gill, 1978a) to compare differences in response
when there were significant interactions between diets and

periods.

RESULTS AND DISCUSSION
Distillers Net Grains
Experiment I. Stability During Aerobic Storage

Table 6 shows temperature changes of distillers wet
grains (DNG) as affected by increasing levels of added
ammonia and days of aerobic exposure at three storage
temperatures. Changes in temperature in response to the
imposed variables were not consistent within or across
storage temperatures. Heating, however, as evidenced by
increases above storage temperatures, was greater for
untreated and low ammonia-treated grains than for those
treated with intermediate or high ammonia, especially at
the high temperature. For untreated, low, intermediate and
high ammonia treatments, peak increases above the high
storage temperature averaged (00) 11.11, 6.66, 3.89 and
2.22, respectively. At intermediate and low storage temper-
atures, peak increases were less than 10°C, suggesting
that heating is not independent of storage temperatures.
However, the fact that increases in temperature were
decreased with increasing levels of added ammonia suggests
that heating could also be due to aerobic microbial meta-
bolism. Other studies have reported similar results for

ammonia-treated DNG stored under aerobic conditions

34

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36
(Naller g3 gl., 1982; Huber §£_§I., 1983; Diallo 22 gl.,
1984). Increased storage temperatures resulted in a general
decrease in days to equal or exceed that specified temper-
ature, which were 14, 9 and 4 for low, intermediate and
high storage temperatures, respectively.

Changes in appearance of the stored grains during
aerobic exposure were not tabulated. However, grains treated
with intermediate or high ammonia showed no visible mold
growth during aerobic storage at any of the specified
temperatures, probably due to the anti-fungal action of
ammonia (Bothast 23 gl., 1973; Britt and Huber, 1975; Huber
g3 gl., 1979b). In contrast, substantial mold growth during
storage was observed for untreated and low ammonia-treated
grains, especially at intermediate and high storage temper-
atures. Similar observations were reported for DNG treated,
on a dry matter basis, with less than 3% ammonia (Waller
23 gl., 1982), suggesting that low levels of ammonia might
serve as a nitrogen source for fungal growth, since many
fungi including most Penicillia and Aspergilli utilize
ammonium salts as a nitrogen source (Bothast g3 gl., 1973).
Days until appearance of visible mold on the untreated and
low ammonia treated grains also decreased with increasing
storage temperatures. Average days at low, intermediate
and high temperatures for untreated and low ammonia treat-
ments were 10, 11; 7, 6; and 4, 4, respectively.

Dry matter recoveries of DNG as affected by ammonia

treatments and storage temperatures after 14 days of

37

aerobic storage are shown in Table 7. As expected, dry
matter recoveries decreased with increasing storage temper-
atures, probably because of dependent temperatures increases
in the stored grains (Table 6) resulting in enhanced aerobic
microbial activity (Mo and Fyrileiv, 1979). The similarity .
in recoveries for untreated grains at intermediate and high
temperatures cannot be readily explained. However, recov-
eries were higher with increased ammonia. The improved
recoveries with intermediate and high ammonia was probably
due to the anti-fungal action of ammonia in suppressing
aerobic degradation and consequent heating, as evidenced

in Table 6. The relationship between dry matter recovery

and the combined effects of increasing ammonia additions

and storage temperatures can best be described as being
linear by linear, linear by quadratic or quadratic by
quadratic.

Ammonia additions to the wet grains resulted in
substantially higher initial pH levels than in the untreated
grains (Table 8). However, with the exception of the
untreated grains, decreases in pH to day 14 were slow and
also inversely related to level of ammonia at intermediate
and high temperature. This inverse relationship was
probably due to the increased efficacy of ammonia at
higher concentrations in inhibiting aerobic microbial
activity (Bothast 23 gl., 1973; Britt and Huber, 1975)
shown to be associated with increases in pH (Mo and

Fyrileiv, 1979). For the untreated grains, pH by day 14 at

38

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39

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40

low, intermediate and high storage temperatures were 0.58,
3.71 and 3.72 units higher than the initial level of 4.15,
which is not surprising in view of the observed temperature
increases (Table 6) and the substantial mold growth at
intermediate and high storage temperatures. Even with the
low pH of 4.73 by day 14 at the low storage temperature,
mold growth was not inhibited in untreated grains.

Apart from the initial increases in total nitrogen
from ammonia additions at day 0, changes in total nitrogen
during aerobic exposure appeared to be influenced mainly
by storage temperatures (Table 9). With the untreated
grains, total nitrogen increased from 4.07% (of the dry
matter) at day 0 to 4.39, 5.23 and 5.83% at day 14 for low,
intermediate and high storage temperatures, respectively,
probably due to loss of CO2 during storage. A similar
response was observed at low and intermediate storage
temperatures for low ammonia-treated grains, but at high
temperature total nitrogen decreased from 5.10% at day 0
to 4.19% by day 14, probably due to volatilization of added
nitrogen (Fox and Fenderson, 1978). Unlike untreated and
low ammonia (except at high temperature)-treated grains,
total nitrogen (at day 14) decreased with increasing
storage temperatures for grains treated with intermediate
or high ammonia, with decreases greater for high than for
intermediate ammonia. However, the fact that decreases did
not result in concentrations less than 4.07% (total

nitrogen of untreated grains at day 0) suggests that the

41

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42
decreases were due to volatilization of some of the added
nitrogen.

As expected, water soluble nitrogen (NSN) increased
with ammonia additions (Table 10). However, during aerobic
exposure, increases to day 14 were greater for untreated
and low ammonia-grains than for grains treated with inter-
mediate or high ammonia. At low, intermediate and high
storage temperatures, NSN increased 2.3-, 21.4- and 24.8
fold for the untreated grains, whereas with low ammonia,
concentrations increased 2.8-, 3.5- and 2.4 fold. Nith
intermediate ammonia treatment, concentrations of NSN were
lower than the initial levels at low and intermediate tem-
perature, but increased 1.18 fold during exposure at the
high temperature. Unlike the other treatments, concentra-
tions of NSN for high ammonia were never higher than ini-
tial levels, irrespective of storage temperatures, thus
indicating decreased proteolysis with increasing ammonia
additions. Similar results were reported for ammonia-
treated corn silage (Johnson g: gl., 1982). The tendency
for increases in NSN with intermediate and high ammonia
during aerobic exposure was probably due to lower nitrogen
retention by unfermented material (Huber 33 gl., 1979a).

Ammonia nitrogen (NH3-N) concentrations also increased
with ammonia additions (Table 11). However, for untreated
grains, no NH3-N (except for trace amounts which were less
than 0.001% of the dry matter) was detected at the low

storage temperature, but with increasing temperatures

43

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45

(storage), days to exceed initial concentrations were
reduced from 9 to 4 days. In addition, although the rate

of increase was greater at high than at the intermediate
temperature, concentrations were about the same by day 14
(0.57 vs. 0.59% of the dry matter), indicating a catalytic
effect of increasing temperatures on deamination activity.
With the ammonia treatments, changes in NSN concentrations
during aerobic exposure were less consistent across storage
temperatures. However, based on the added levels of NH3-N
(1.29. 2.58 and 3.87%) rather than the levels of added
ammonia (1.57, 3.14 and 4.71%), essentially all of the
increases in NHg-N for ammonia treatments could be accounted
for by increased solubilization of added ammonia, assuming
that some ammonia was incorporated into microbial protein
and that a portion of such protein was solubilized through

proteolysis (Huber gt gl., 1979a).

Summar

The results from this study have shown that treating
fresh distillers wet grains (FDNG) with 3 to 4% (of the
dry matter) ammonia not only improves the aerobic stabil-
ity of the material during increasing ambient temperatures,
but also retards heating, eliminates mold growth, improves
dry matter recovery and reduces proteolysis and deamination
over a two-week period. It was also shown that treating
FDNG with 1.6% (of the dry matter) ammonia, results in an

unstable material which deteriorated faster than untreated

grains.

46

Expggiment II. Lactation Trial

Treating the fresh DNG with 4-5% (of the dry matter)
ammonia resulted in adequate preservation of the wet grains
during bi-weekly deliveries. No mold growth or extensive
temperature increases above ambient temperatures (10-2700)
were observed in the treated grains during storage and
feeding out. Dry matter was reduced from 31 to 28% with
ammonia treatment, but crude protein was increased from
27 to 39.5% (range was 37-42%) of the dry matter.

Table 12 shows the chemical composition of the diets
(Table 3) that were fed during the experimental period.
The DNG diet was lower in dry matter, but higher in the
detergent fractions (acid detergent insoluble nitrogen,
acid detergent fiber and neutral detergent fiber) than the
soybean meal (SBM) diet. The greater pr0portions of corn
silage and haylage together with the ammoniated DNG (Table
3) could account for these differences. Differences in
crude protein, estimated net energy of lactation (NEL)
and pH between the diets were small.

Dry matter intakes, though not significantly different
between groups, tended to be lower for cows fed the DN6
diet (Table 13). This was probably due to the higher
moisture content and/or the higher detergent fractions of
the total diet. Actual, fat and solids corrected milk with
their corresponding efficiencies tended to be higher for
cows fed the DN6 diet, but due to the large associated

standard errors, no significant differences were detected

47

Table 12. Chemical composition of the experimental diets

 

 

 

‘, Dietsa___
Item SBM D 6
Dry matter (%) 46.1 39.4
Crude protein (% of DM) 14.5 14.4
Acid detergent insol. N (% of total N) 5.9 11.4
Acid detergent fiber (% of DM) 21.5 23.4
Neutral detergent fiber (% of on) 35.7 42.3
Estimated NEL (Mcal/kg pm)b 1.61 1.64
pH 5.1 5.4

 

aSoybgan meal (SBM) and ammoniated-distillers wet grains
DNG .
Net energy of lactation (NEL) was calculated from Telplan

Program 31 Form 3 (MSU, 1981).

48

Table 13. Dry matter intake, milk yields and persistencies
of cows fed the experimental diets

 

 

Dietsa
Variable §Efi"“‘DWO' SE Effect
Dry matter intake (kg/d) 19.4 17.6 5.74 NSd
Milk yields (kg/d)b
Actual 27.1 27.9 1.30 NS
Fat-corrected 23.8 24.8 1.10 NS
Solids-corrected 23.9 24.7 1.49 NS
Persistencies (%)c
Actual 90.9 94.3 5.61 NS
Fat-corrected 88.0 91.4 4.69 NS
Solids-corrected 85.8 88.5 6.46 NS

 

aSoybean meal (SBM) and ammoniated distillers wet grains

(DNG).

:Adjusted by covariance analysis. .
d(Treatment milk/ re-treatment milk)x 100.
Not significant {P > .05).

49

between treatment groups. Similar results were reported by
Schingoethe §3_§l. (1983) for cows (averaging 84 days
postpartum) fed DNG or SBM supplemented diets.

Milk composition, feed efficiency and average daily
gains of cows fed the experimental diets are in Table 14.
Milk fat, protein and solids-not-fat were not significantly
different between treatment groups. The tendency, however,
for lower milk protein for cows on the DN6 diet was probably
due to a greater proportion of the dietary nitrogen being
tied up as acid detergent insoluble nitrogen (Table 12).
Similar results were reported for distillers dried grains
and extruded and heat-treated soybean meal (Kung §t_§l.,
1983; Satter and Stehr, 1984), all of which undergo some
degree of heating. However, cows fed the DN6 diet were more
efficient (P‘<.05) in converting feed to milk. This improved
feed efficiency was probably due to more efficient utiliza-
tion of the nutrients in the DN6 diet than those in the SBM
diet, since there were no significant treatment differences
in average daily gains.

Table 15 shows the profitability of the experimental
diets. The costs of the various feed ingredients used in
the diets are representative of the prices paid by farmers
in Michigan in 1985. Based on these prices and actual milk
yield and feed intake data, lower feed costs and greater
income over feed costs were realized when ammoniated DNG
supplied the supplemental protein to basal diets. Both DNG
and SBM supplied approximately 40% of the dietary protein.

50

Table 14. Milk composition, feed efficiency and average
daily gains of cows fed the experimental diets

 

 

Dietsa

Variable SBM DNG SE Effect
Milk composition (%)b

Fat 3.19 5.27 .166 NSC

Protein 3.17 3.07 .102 NS

Solids-not-fat 8.55 8.63 .537 NS
Feed efficiency

(kg 4%-FCM/kg DM) 1.25 1.42 .139 .05
Average daily gain (kg/d) .41 .42 .251 NS

 

aSoybgan meal (SBM) and ammoniated distillers wet grains
DWG .

:Adjusted by covariance analysis.

Not significant (P >.05).

51

Table 15. Economic evaluation of the experimental diets

 

 

 

_ Dietsa _

Item S NG
Milk yield (kg/day)a 27.1 27.9
Milk income (3/cow/day)b .7.17 7.38
Feed intake (kg DM/day) 19.38 17.56
Feed price (s/M ton DM)c 126.09 113.94
Feed cost ($/cow/day) 2.44 2.00
Income over feed costs

($/COW/day) 4.73 5.38

 

aSoybean meal (SBM) and ammoniated distillers wet grains

b(Dwo). '

cAdjusted by covariance analysis.

dMilk price @ 812/cwt or $0.2646¢/k .
Price of ration ingredients (3/ton : corn
alfalfa hay, 80; corn 107 ($3.00/bushel);
soybean meal, 160; distillers wet grains,
ammonia, 250; vitamin-mineral mixes, 300.

silage, 22;
haylage, 35;
30; anhydrous

52

Summary
Ammonia treatment of fresh DNG (at 4-5% of the dry

matter) provided adequate preservation of the wet grains
during feeding out of bi-weekly deliveries. The treated
grains (DNG) were equal to soybean meal in maintaining
milk yields and milk composition of cows fed these supple-
ments to supply approximately 40% of their dietary protein
in total-mixed diets. Dry matter intakes on the DN6 diet
were 1.8 kg lower than on the SBM diet, but cows were more
efficient in converting feed to milk. In addition, economic
evaluation of the diets showed a greater return over feed
costs when DNG supplied the supplemental protein to total-
mixed diets consisting of corn silage, haylage,alfalfa

hay, high-moisture ear corn and a vitamin-mineral mix.

nggggs Net Graygg
Eyperiment Ia.

Stability During Aerobic and Anaerobic Storage

An interaction (P $.05) between ammonia additions, and
days of aerobic or anaerobic (ensiling) storage was indi-
cated by the analysis of variance for each response vari-
able in this study, with the exception of dry matter
(anaerobic only - Table 17) and acetic acid (aerobic and
anaerobic - Table 21) for which main effect means are
presented in addition to the treatment combination means.

Changes in temperature and dry matter of brewers wet

grains (BN6) during aerobic storage are shown in Table 16.

53
Ammonia treatment of the wet grains (at day 0) resulted in
an immediate decrease of the initial temperature (52.22 vs.
41.11 and 41.6700). Since the initial temperature of the
wet grains is a residual effect of the brewing process, it
is theorized that the mechanism of action of ammonia in
decreasing this initial temperature might be through a
cooling effect of ammonia on the wet grains, rather than
the anti-fungal action of ammonia (Bothast 23 gl., 1973;
Britt and Huber, 1975) in suppressing aerobic microbial
activity and thus preventing temperature increases. However,
though inconsistent, temperatures decreased during storage
with less drastic differences between treatments, probably
due to adequate compaction of the wet grains in the plastic
containers. Ambient temperatures fluctuated between 22 and
29°C.

Initial dry matter concentrations of BN6 appeared less
affected by ammonia additions (Table 16), probably due to
volatilization of some of the added ammonia during dry
matter determination by oven drying (Fox and Fenderson,
1978). However during aerobic exposure, dry matter decreases
(% of initial dry matter) to day 10 averaged 3.7, 4.3 and
1.7% for untreated, low and high ammonia treatments.

Mold growth and spoilage data for BN6 during aerobic
storage are not tabulated. However, these were evident
only in the untreated and low ammonia-treated grains.

Visible mold was evident in the untreated grains at day 6,

54

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55

and in the low ammonia-treated grains at day 9. Of the 18
cm of compacted grains, spoilage by day 10 averaged 2.5,
1.3 and 0 cm from the surface for untreated, low and high
ammonia-treated grains. The delayed spoilage with increased
ammonia was due to the anti-fungal action of ammonia.
Bothast gt El- (1923) reported that both external and
infecting molds and yeast were eliminated in high moisture
corn treated with .5 or 2% of the dry matter as ammonia.

Changes in dry matter concentrations of BWG during
ensiling are shown in Table 17. Dry matter concentrations
of the wet grains were more stable during ensiling than
when subjected to aerobic exposure. This difference could
be attributed to the decreased oxygen tension in the ensiled
grains. Zimmer (1971) demonstrated an inverse relationship
between dry matter losses associated with the storage of
high moisture material and the degree of air-tightness
achieved. However, despite the improved stability under
anaerobic (ensiling) conditions, low ammonia addition
resulted in decreased dry matter concentrations when com-
pared to untreated and high ammonia treatments. Since the
interaction between ammonia treatments and days of aerobic
exposure was not significant, the relationship between dry
matter changes and ammonia additions can best be described
as being quadratic (P'<.O1). Day effect was not significant,
as indicated by the contrasts.

Table 18 shows the pH changes of BWG during aerobic

56

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57

storage and ensiling. As was expected, ammonia treatments
increased initial pH values (5.10 vs. 9.69 and 10.03, for
untreated, low and high ammonia treatments), but resulted
in delayed decreases in pH during aerobic storage and
ensiling. Under aerobic storage, initial pH of untreated
grains decreased to a low of 4.07 by day 7, followed by a
slow increase to 4.40 by day 10. These changes were prob-
ably associated with the production and destruction of
organic acids. With the ammonia treated grains, pH values
by day 10 were still alkaline (8.20 and 9.62 for low and
high ammonia treatments), presumably due to the higher
initial pH and restricted fermentation. For the ensiled
grains, pH values for the untreated grains decreased to a
low of 3.68 within the first week of ensiling, followed by
a slow increase to 4.46 by day 28. The low pH of 3.68
suggests that fermentation was complete by the first week
of ensiling; whereas, the increased pH thereafter could be
associated with clostridial activity (No and Fyrileiv,
1979). For the ammonia treatments, pH decreases were greater
with low than with high ammonia; average decreases from
days 0 to 28 were 4.11 and 0.35 pH units, respectively,
indicating greater fermentative activity with low ammonia.
The pH values for the untreated ensiled grains are in
agreement with those reported by Allen and Stevenson (1975)
for untreated BWG ensiled in laboratory silos.

Ammonia treatments resulted in delayed increases in

58

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59

lactic acid production (Table 19). Lactic acid concentra-
tions at day 0 for untreated, low and high ammonia-treated
grains were: 1.02, 0.51 and 0.66% of the dry matter. The
reason for the lower concentrations in the ammonia-treated
grains is not apparent. However, during aerobic storage
lactic acid production peaked at day 7, with concentrations
greater for the untreated than the ammonia-treated grains
(3.43 vs. 0.70 and 0.83%), probably due to the lower pH
levels in the untreated grains (Table 18). At the end of
the aerobic storage period (day 10), lactic acid concentra-
tions were 52, 70 and 68% of the levels observed at day 7
for untreated, low and high ammonia treatments, suggesting
greater stability for ammonia treatments under aerobic
exposure. During ensiling, lactic acid production also
peaked at day 7 with concentrations of lactic acid higher
in the untreated than in the ammonia treated grains (3.53
vs. 0.76 and 0.70%). This difference is also related to the
more favorable pH‘levels in the untreated grains (Table 18)
for lactic acid producing bacteria. However, with increasing
days of ensiling lactic acid decreased, with concentrations
at day 28 averaging 8.2, 14.5 and 71.4% of the levels
observed at day 7, again suggesting greater stability for
ammonia treatments during extended periods of ensiling

(or anaerobic storage). The lower lactic acid levels with
ammonia treatment are characteristic of ammonia additions
in excess of 1% of the dry matter (Britt and Huber, 1975;
Huber gt al., 1979a; Johnson gt El: 1982).

6O

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61

Residual water soluble carbohydrates (WSC) concentra-
tions were higher in the ammonia-treated than the untreated
grains (Table 20). Average concentrations at day 0 for
untreated, low and high ammonia treatments were: 6.39, 8.42
and 7.19% of the dry matter. The increased concentrations
with ammonia treatments were probably due to the action 0f
ammonia in hydrolyzing hemicellulose (Harbes 23 al., 1982).
During aerobic storage, WSC concentrations decreased in
untreated and low ammonia-treated grains, but increased in
grains treated with high ammonia probably due to decreased
utilization for lactic acid production coupled with the
residual action of ammonia in hydrolyzing hemicellulose.
The rapid decrease in concentration of WSC for low ammonia
treatment between days 7 and 10 is surprising, since there
was no corresponding increase in lactic acid production
(Table 19), which suggests that the rapid decrease could
be due to the production of other organic acids (Whittenbury
§§.§;., 1967), or to utilization by aerobic microbes (Mo
and Fyrileiv, 1979). During ensiling, WSC concentrations in
the untreated grains were lower than the initial concentra-
tion, probably due to partial utilization for lactic acid
production. However, as was observed during aerobic storage,
there was a tendency for small increases in WSC in the
untreated grains, which was probably due to the slow
hydrolysis of hemicelluose by organic acids at the lower

pH (Woolford, 1972; Ohyama and Masaki, 1977). For low

62

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way OHHmHumsw .AHV HamsHH

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Ho. Ho. Ho. Ho. Ho. Ho. cmHHmsm
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oxno oxH cdxco coxn cho ng "ompmMHpcoo
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ma cmpomHHm mm musnm pm: mpmsmhp :H mmpmnchzonHMc mHQsHom Hmpmz Hmschmm Amw oHpme

63

ammonia-treated grains, WSC concentrations decreased with
increasing days of ensiling, which is indeed surprising in
view of the decreasing concentrations of lactic acid with
increasing days of ensiling (Table 19). The pH decline
(Table 18) between days 14 and 28 was optimum for lactic
acid producing bacteria, which suggests that lactic acid
was produced, but was converted to other organic acids by
clostridial microbes (Mo and Fyrileiv, 1979). For the grains
treated with high ammonia, WSC concentrations increased to
day 7 (7.19 to 9.76%), then showed a slight tendency to
decrease with increasing days of ensiling.

Acetic acid concentrations were generally higher during
ensiling than during aerobic storage (Table 21). The
interactions between ammonia treatments and days of aerobic
storage or ensiling were not significant. However, during
aerobic storage, acetic acid production increased, with
concentrations greater in the ammonia-treated than in the
untreated grains. The reason for the greater concentrations
with ammonia treatments is not apparent, but it can be
speculated that there was probably greater stimulation of
the homofermentative acetic acid bacteria (Mo and Fyrileiv,
1979) which are known to produce acetic acid from ethanol
in the presence of oxygen. Ethanol production was not
measured in our study, but its presence in BWG was confirmed
by Oleas (1977). For the ensiled grains, acetic acid
production also increased with increasing days of ensiling,

but concentrations were greater for untreated and low

64

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m2 mo mpommmm ADV guano cam Aoov oupmpemsa .Agv semen;
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pamEHanp A mzv chosem an cmpommmm mm msHmHm pm: mnmzmnn :H cHom 0Hpm0< .HN mHnme

65

ammonia treated grains than for grains treated with high
ammonia. This difference was probably due to the restricted
fermentation with high ammonia treatment, since acetic acid
production is usually looked upon as a normal process during
ensiling (Whittenbury gt al., 1967). .

Except for butyric and acetic acids, no other volatile
fatty acids were detected in any of the sampled grains.
Butyric acid values are not tabulated. However, under
aerobic storage, butyric acid was detected at day 10 only
in the untreated grains; the concentration was 0.16% of the
dry matter. For the ensiled grains, butyric acid was
detected only for the low ammonia treatment. At day 14,
concentrations averaged 0.53% of the dry matter, but
increased to 4.18% by day 28. The fact that lactic acid
(Table 19) and WSC (Table 20) concentrations decreased "
drastically during the same time interval, suggests that
they were utilized by saccharolytic clostridia (Whittenbury
gt,§;., 1967; Mo and Fyrileiv, 1979), thus resulting in the
production of butyric acid.

Changes in total nitrogen (N) concentrations during
aerobic storage and ensiling are shown in Table 22. As was
expected, initial concentrations were increased with ammonia
additions; average concentrations were 4.41, 5.45 and 6.65%
of the dry matter for untreated, low and high ammonia treat-
ments. During aerobic storage, average N concentrations by
day 10 were 10.7, 12.5 and 5.6% greater than initial concen-

trations at day 0. These differences could be attributed to

66

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mzv mHnossm an nmpommmm mm msHmnw Hm: mnmzmhp :H ammoHpH: HmHoe .NN oHnme

67

the dry matter losses as reflected in the decreases in dry
matter percent (Table 16). For the ensiled grains, total
nitrogen also increased during ensiling. By day 28, average
concentrations for untreated, low and high ammonia treat-
ments were 10.2, 21.5 and 4.4% greater than initial concen-°
trations. The greater increase in total nitrogen concentra-
tion for low ammonia-treated grains was probably due to
the increased production of butyric acid which often results
in large losses of dry matter (Mo and Fyrileiv, 1979).
Water soluble nitrogen (WSN) concentrations also
increased initially with ammonia additions (Table 23).
Initial concentrations for untreated, low and high ammonia
treatments were 3.28, 33.09 and 46.42% of total nitrogen.
During aerobic storage and ensiling WSN concentrations
increased in the untreated grains, suggesting increased
proteolysis of the grain protein. Average WSN concentra-
tions by day 10 and 28 for aerobic storage and ensiling,
respectively, were 18.9 and 71.6% greater than the initial
concentration. For the ammonia-treated grains, there was
no consistent change in WSN concentrations during either
storage system, the reasons for which are not apparent.
Ammonia additions resulted in initial increases in
ammonia nitrogen (NHB-N) concentrations (Table 24). For
untreated, low and high ammonia, 0.79, 7.79 and 8.50% of
total nitrogen (or .04, .42 and .56% of the dry matter)
was NBS-N. During aerobic storage, NHB-N increased with

concentrations by day 10 averaging 5.48, 17.22 and 21.01%

68

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.Amhmcn

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.Nmm.H cam mom. ohm mm m>Hpom mop “Ho.v m I mnHHHmsm Ho

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m

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69

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70

of total nitrogen (or .17, 1.05 and 1.48% of the dry
matter). During ensiling, NHB-N also increased with concen-
trations by day 28 averaging 1.74, 25.25 and 25.82% of total
nitrogen (or .08, 1.67 and 1.79% of the dry matter). Based.
on the levels of added NHB-N (0, 1.65 and 5.29%) rather than
added NH3 (0, 2 and 4%), it is suggested that the increases
with time in NHB-N with high ammonia treatment were due to
solubilization of added N which was initially bound in the
water insoluble form (Huber gt al., 1979a). For the low
ammonia treatment, it seems reasonable to conclude that the
increases in NHB-N were due to solubilization of added N
plus deamination of amino acids (Johnson gt gl., 1982).
Whereas, with the untreated grains, the increases in NHB-N
could only be due to deamination of amino acids. Moreover,
this activity appeared to be greater during aerobic storage
than during ensiling, probably because of a slower decline
in pH during aerobic exposure (Table 18).

At the end of the ensiling period, untreated and low
ammonia~treated grains had a bleached-like appearance and
a strong acid smell. Whereas, with the high ammonia-treated
grains, there was still the brown appearance (from ammonia

treatment) and a strong ammonia odor.

Summar
The results obtained in this study, indicate that the
mechanism influencing the stability of EWG during aerobic

and anaerobic storage is complex and not determined by a

71

single factor. However, greater quality retention was shown
for anaerobic (ensiling) than aerobic stroage. Also, the‘
high ammonia treatment (4% of the DM) was most effective

in preserving the quality of the wet grains during aerobic
and anaerobic storage.

Experiment Ila. Lactation Trial

In the following tables, the abbreviations SBM, FBWG,
EBWG and FBWGU will be used to designate the diets supple-
mented with soybean meal, fresh brewers wet grains, ensiled
brewers wet grains and fresh brewers wet grains plus urea,
respectively.

Table 25 shows the average chemical composition of
diets fed during the experiment. Dry matter content of the
brewers wet grains (BWG) diets were generally lower than
the SBM diet. Also, acid detergent fiber was higher in FBWG

and EBWG diets than in SBM and FBWGU diets. These differ-
Vences were due to the relative proportions of BWG added to
the diets (Table 4). Diets were formulated to be isonitro-
genous (15.5% GP); however, crude protein (0P) analysis for
the respective diets were 0.77, 0.15, 0.59 and 0.27 units
lower than intended. In addition, a greater proportion of
the dietary protein (N x 6.25) was acid detergent insoluble
nitrogen in the BWG diets than the SBM diet.

Chemical composition of fresh and ensiled BWG fed
during the experiment is in Table 26. Mean values were simi-

lar for fresh and ensiled grains. However, the increase in

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72

 

 

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74

lactic acid, and the decrease in pH and soluble carbohy-
drates indicate that some fermentation occurred during
storage. The pH and ammonia nitrogen values of the ensiled
grains were within accepted critical limits (a pH of less
than or equal to 4.2 and NHB-N less than or equal to 8%

of total N) suggested for satisfactory preservation
(Carpintero gt §;., 1969).

Percent undegraded (ig_zit£g) and water soluble
nitrogen of the diets fed during the experiment are shown
in Table 27. Undegraded nitrogen at zero hours, which
corresponds to the solubilization of the more rapidly
degradable fraction of the feed protein, was highest for
FBWG (69.5%) and least for FBWGU (55.8%). These differences
could be accounted for by the relative proportions of water-
soluble nitrogen (% of total N) in the respective diets.
However, after 1 hour of incubation, which is closely
related to the relative rate of degradation in the rumen
(Poos gt al., 1979), undegraded nitrogen values were 45.2,
40.5, 55.8 and 28.6% of the total N for EBWG, FBWG, FBWGU
and SBM diets, respectively. These values are in agreement
with in_zi1g estimates of undegradable protein in diets
supplemented with soybean meal or brewers wet grains
(Santos _ej; a” 1984).

Analysis of variance for dry matter intakes indicated
an interaction (P4<.01) for diet by period. In view of this,

period means for the different treatments are presented

75

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76

(Table 28). Dry matter intakes were consistently higher
for cows fed the SBM diet. This trend was reflected by a
greater difference in linearity (P.<.005) when SBM was
compared with FBWG + FBWGU or with EBWG. The higher intakes
on FBWGU than the FBWG diet (though not significant) pro- '
bably resulted from replacing approximately 45% of the
fresh brewers wet grains with its crude protein equivalent
_from urea and its energy from corn (Table 4). The relatively
lower intakes on the EBWG diet probably resulted from more
of the dietary protein being tied up as acid detergent
insoluble nitrogen (Table 25), coupled with the low level
of water soluble nitrogen in the diet (Table 27). When the
unavailable protein (ADIN) was subtracted from the total
protein, the remaining dietary protein for EBWG was 13.5%
of the dry matter which was below recommended requirements
(NRC, 1978). Although dry matter intakes were relatively
lower on the brewers wet grains diets, others (Murdock gt
gl., 1981) have reported similar intakes for cows fed
brewers wet grains at 15 or 50% of dietary dry matter.
However, depressed intakes were reported for cows fed
greater than 50% of dietary dry matter as brewers wet grains
(Davis 22 gl., 1985).

Table 29 shows milk yields, persistencies and milk
composition of cows fed the experimental diets. The inter-
action for diet by period was not significant, thus only

treatment means are presented. There were no significant

77

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79

treatment differences in yields of milk, 4% fat-corrected
milk (FCM) and solids-corrected milk (SBM). Also, treatment
differences for persistencies and milk composition were not
significant.

Body weight gains and feed efficiencies are shown in
Table 50. The interaction for diet by period was not signif-
icant (P 7.05), thus only treatment means are presented.
Body weight gains and feed efficiencies (milk/kg DM intake)
were numerically greater for the FBWG and EBWG than the
other diets, but differences were not significant for any
of the contrasts (shown in the foot-notes). The reason for
the improved feed efficiencies for cows fed the BWG diets
is not apparent. However, since the cows were weighed only
during the second and last week of the experiment, any
losses in body weight in support of milk production could
have been negated by greater gains (in body weight) between
the second and last week of the experiment. Davis gt gt.
(1985) reported improved feed efficiency for cows fed
brewers wet grains diets, but the apparent increase in feed
efficiency, compared to cows fed the soybean meal diet, was
accounted for by losses in body weight.

The relative profitability of the different protein
supplements is presented in Table 51. Income over feed
costs was lowest for SBM and greatest for FBWGU. The reason
for the higher profit on the brewers grains diets compared

to SBM, was the lower cost of protein supplement and the

80

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higher feed intake on the SBM diet with only small differ-
ences in milk yields. Even if intakes had been equal for
all the diets, the SBM diet would have still been the least
profitable. An additional savings was also realized when
part of the fresh brewers grains was replaced with urea and
ear corn. However, a different set of feed prices could
have changed the relative rankings of the diets, but these
were the prices the author felt as representative of the
feeds in Central Michigan during 1985.
Summary

The results obtained in this study indicate that the
forms of brewers wet grains studied were equal as replace-
ments for soybean meal in diets for lactating dairy cows.
In addition, greater income over feed cost were realized

on the brewers wet grains than on the soybean meal diet.

GENERAL SUMMARY

The results obtained from the DWG stability study
indicated that the wet grains can be effectively preserved
for 2 weeks or more when treated with ammonia at 3 to 4%
of its dry matter. At these application rates, dry matter
recovery was improved, mold growth and spoilage were
inhibited and temperature increases above storage temper-
ature were reduced. For untreated and low ammonia treated
grains, mold growth and spoilage increased with increasing
storage temperature. Based on the intensity of mold growth
during storage, the average shelf life of untreated and
low ammonia-treated grains was 11, 7 and less than 4 days
at 166 (15.600), intermediate (26.700) and high (37.800)
storage temperatures.

In the DWG lactation trial, ammonia-treated DWG (4-5%
of the DM) were equal to soybean meal in maintaining milk
yields and milk composition of cows fed these supplements
to supply approximately 40% of the dietary protein in total
mixed diets. Intakes were higher on the SBM diet, but cows
fed DWG were more efficient in converting feed to milk. In
addition, greater income over feed cost was realized on
the DWG diet.

For the aerobic and anaerobic (ensiling) stability

studies with BWG, the results obtained indicated that BWG

83

84

can be effectively preserved during aerobic storage and
ensiling when treated with 4% of its dry matter as ammonia.
Visible mold growth was evident in the untreated grains at
day 6 and in the low ammonia (2% of DM) grains at day 9,
during aerobic storage. Subsurface spoilage was also greater
for untreated than low ammonia grains during aerobic
storage. At the end of the ensiling period, high ammonia
grains retained its original color, but had a strong odor
of ammonia; whereas, with untreated and low-ammonia treated
grains, the original color had faded and there was a strong
acid odor.

In the BWG lactation trial, the forms of brewers wet
grains studied were equal to soybean meal in diets for
lactating dairy cows. By reducing the amount of brewers
wet grains fed, and replacing its crude protein equivalent
with urea and its energy with corn, greater dry matter
intakes were achieved. Ensiled brewers wet grains in the
diets of lactating dairy cattle resulted in about 7% lower
dry matter intakes than fresh brewers wet grains. A longer
adaptation period to the diet probably might have improved
intakes. However, ensiling can be practiced as a method for
storage of brewers wet grains. In addition, incorporation
of brewers wet grains into diets for lactating dairy cows
should be a gradual process to allow cows to adjust to the
new diets.

The fresh brewers grains were more profitable than

85

soybean meal, and ensiled grains were intermediate. Use of
urea with fresh brewers grains resulted in greatest income
over feed costs, and appears to be a desirable alternative
to soybean meal as a protein supplement for high producing
dairy cows.

Future studies are needed to clarify the mechanism of
action of ammonia in increasing the soluble carbohydrates
in brewers wet grains during aerobic storage and ensiling.
Such studies will be useful in evaluating the potential
digestibility and energy value of the wet grains for

ruminants.

APPENDICES

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