xt7r7s7hs151 https://exploreuk.uky.edu/dips/xt7r7s7hs151/data/mets.xml   Kentucky Agricultural Experiment Station. 1967 journals 170 English Lexington : Agricultural Experiment Station, University of Kentucky Contact the Special Collections Research Center for information regarding rights and use of this collection. Kentucky Agricultural Experiment Station Progress report (Kentucky Agricultural Experiment Station) n.170 text Progress report (Kentucky Agricultural Experiment Station) n.170 1967 2014 true xt7r7s7hs151 section xt7r7s7hs151 J!
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UNIVERSITY OF KENTUCKY • AGRICULTURAL EXPERIMENT STATION • PROGRESS REPORT I7O

 PROGRAMS FOR I967 ANIMAL SCIENCES FIELD DAYS
DAIRY FIELD DAYS
June I9, I967 Western Kentucky University Farm, Bowling Green
June 20, I967 University Coldstream Dairy Center, Lexington
·· Demonstrations and exhibits of recommended practices and current problems Facing
the dairy industry beginning at IO a.m .
·· Lunch provided by American Dairy Association of Kentucky, Mammoth Cave
Production Credit Association, Dairy Products Association, Aubrey Feed Mills,
Kyana Milk Producers, Inc ., Sealtest Foods and Southern States Cooperative.
- Address -- "The Business Side of Dairying" - Mr. L. P. Lango, author in "Hoard's
Dairyman" and dairyman, Glastonbury, Conn.
LIVESTOCK FIELD DAYS
July I2, I967 University Coldstream Farm, Lexington
July I4, I967 Western Kentucky Substation Farm, Princeton
- Conducted tours showing beef, sheep and swine research at regular intervals
beginning at 9 a.m.
· Lunch provided by Bluegrass Stockyards, Lexington,and Field Packing Co. and
Owensboro Milking Co. , Owensboro.
- Address ·- "Can We Produce Enough?" - Dr. A. L. Neumann, head, Department
of Animal Science, New Mexico State University, University Park, New Mexico.
TI-IE COVER ILLUSTRATION shows a model of the proposed layout of the University of Kentucky Agricultural
Research Center. Included are the existing Agriculmral Science building with auditorium (upper left) and
greenhouses (upper right), a new Animal Sciences building to be constructed (center), and projected additional
laboratory, office and parking facilities (lower right). The sum of $4 million has been allocated for construction
of the new Animal Sciences building , which will contain approximately 110,000 square feet of floor space.
Preliminary program requirement plans have been prepared , architectural design has been begun, and occupancy
is forecast for the fall of 1970.

 KENTUCKY
ANIMAL SCIENCES RESEARCH REPORTS
1967
PROGRESS REPORT 170
Jxme 1967
" UNIVERSITY OF KENTUCKY
AGRICULTURAL EXPERIMENT STATION

 CONTENTS
_ Page `
ANIMAL NUTRITION
Abomasal Nitrogen in Steers Fed Soybean Meal or Urea ............. 5
Plasma Amino Acids in Steers Fed Urea Supplements .............. 6
Source of Nitrogen for Supplementing Ground Ear Corn Rations for `
Feedlot Cattle - 1966 ............................. 8
Vitamin A Turnover in Steers Fed Adequate Vitamin A ............. 11
Influence of Low Dietary Protein on Vitamin A Turnover in Steers ....... 12
Effect of Vitamin E on Pre—Intestinal Disappearance of Vitamin A ....... 14
Effects of Thiabenzole, Injectable Vitamin A and Level of Diethylstilbestrol
Implant on Steer Performance ........................ 15
Evaluating Forage Crops for Beef Production .................. 16
Pre-Abomasal and Post-Abomasal Cellulose Digestion in Steers ........ 20
Digestion of Starch Infused Into the Abomasum of Steers ............ 21
Digestion of Purified Corn Starch in Wethers ................... 23
Action of Cattle, Sheep and Swine Amylase on Various Starches ......... 24
Digestion of Starch in Wethers as Influenced by Dietary Level of Grain ..... 26
Pancreatic Amylase Secretion by Sheep Fed Different Levels of Grain ..... 27
Response of gVitro Starch Digestion by Rumen Microorganisms to
Different Levels and Sources of Sulfur .................... 28
Volatile Fatty Acid Utilization Studies with Rats ................. 29
Plasma and Urine Changes in Vitamin A—Deficient Sheep ............ 30
Effect of Reducing Soybean Protein Solubility by Dry Heat in the Protein
Utilization of Young Lambs .......................... 33
Effect of Protein Level and Solubility on Young Lamb Performance ....... 35
A Technique Employing the Doppler Shift for Measuring Portal Blood
Flow and Portal—Carotid Differences for Absorption from the
Gastrointestinal Tract ............................ 37
How Rate of Stocking and Rate of Grain Feeding Affected Grazing
Results on Two Kinds of Pasture ....................... 39
Voluntary Feed Intake, Milk Production, Rumen Content and Plasma
Free Amino Acid Levels of Lactating Cows on Low-Sulfur and
Sulfur Supplemented Diets .......................... 39
Progress on Assay for Fescue Toxicity ...................... 41
Effects of Nitrate and Nitrites in Feed on the Utilization of Carotene ·
in Swine .................................... 42
Effects of Protein Level and Source on the Serum Protein Profile of · `
Sows and Their Pigs ............................. 45
(2)

 Page
ANIMAL NUTRITION (continued)
Factors Affecting Serum Cholesterol Levels in Swine .............. 47 ‘
Corn Silage for Bred Sows ............................. 49
Influence of Protein Level, Sex and Sire on Performance and Carcass
Characteristics of Swine ........................... 51
Effects of Protein and Iron Sources on Certain Blood Constituents
of Swine .................................... 53
Effect of Implanting Stilbestrol in Pigs Castrated at Birth on Carcass
Characteristics and Performance ...................... 55
GENETICS - PHYSIOLOGY
Metabolism of Labelled Estradiol in Intact, Ovariectomized, and A
_ Hysterectomized Ewes ......,..................... 57
Comparison of Hemocytometer and Coulter Counter for Counting Ram
Sperm Cells .................................. 58
Effects of Hysterectomy in the Anestrous and Prepuberal Ewe ......... 59
Amino Acid Content of Pituitary Glands from Ewes Exposed to
Q Different Photoperiods ............................ 61
Influence of Short-Term Exposure to Continuous or Restricted Light on
Ovulation, Fertility and Embryo Survival Rates in Ewes .......... 62
Effects of Injected Progestogens on the Sexual and Carcass
Characteristics of Boars ........................... 64
Measurement and Selection of Economically Important Traits in
Beef Cattle - 1966 ............................... 66
_ _ Effects of Date of Breeding and Orally Administered Synthetic
Progestogen on Breeding and Lambing Performance of Crossbred
Ewes ...................................... 7 O
Estimates of the Repeatability of Date of Lambing ................ 72
Effect of Induced Cryptorchidism at Different Weights on Performance
~ and Carcass Traits of Lambs ......................... 74
Causes of Variation in Calving Intervals of Dairy Cattle ............. 76
Observations on the Size of Bovine Ova ...................... 76
Causes of Fertilization Failure in Repeat Breeding Cattle ............ 77
Selection for Oxygen Requirements in Chickens ................. 78
Hypoxia in Chick Embryos ............................. 79
(3)

 Page
ANIMAL FOODS
Effect of Fresh Ham Quality on Aged Ham Quality ............... 80
Quality of Aged Hams as Affected by Alternating Aging Temperatures .... 81
Effects of Salt, Moisture and Aging Time on the Viability of
Trichinella spiralis in Dry—Cured Hams ................. 84
Relation of Certain Protein Components and Free Amino Acids to Quality
of Porcine Muscle From Five Different Weights of Hogs ......... 87 ”
Keeping Quality of Whipping Cream and Half-and-Half Obtained at
Retail Outlets ................................ 88
\ Reductive Dechlorination of DDT by Escherichia coli ............. 91
Manufacturing Practices for Chocolate—Flavored Milk and Drink in the
United States ................................ 92
Effect of Filtering and Clarifying Milk on the Catalase and the
Wisconsin Mastitis Test Results ...................... 96
Effect of Chemical Sanitizers on the Wisconsin Mastitis Test ........ 97
Effect of Storage Time on the Wisconsin Mastitis Test ............ 99
Effect of Heat-Shock on the Wisconsin Mastitis Test ............. 100
Factors Which May Influence the Results of the Catalase Test for
Abnormal Milk ............................... 101
Freezing Point of Milk Produced in Kentucky ................. 103
Sour Cream Without Bacterial Cultures .................... 104
Quality Control Programs of Milk Marketing Cooperatives in the
United States ................................ 104
Factors Relating to the Serving of Ice Cream as Dessert with the
Type A School Lunch ............................ 105
(4)

 ..5..
ANIMAL NUTRITION SECTION ·
ABOMASAL NITROGEN IN STEERS FED SOYBEAN MEAL OR UREA
G. D. Potter, C. O. Little and G. E. Mitchell, Jr.
It is well established that ruminal synthesis of protein from nonprotein nitrogen
sources in the ration does occur; however, the objectives in many of the reports on this
subject have been such that little quantitative information has been obtained. The ob-
jective of this study was to identify quantitatively the nitrogenous compounds reaching the
abomasum of steers fed soybean meal (SBM) or urea in a finishing ration.
Procedure
· Four mature steers with permanent abomasal fistulas were used. Rations of
ground ear corn supplemented with soybean meal or urea and containing chromic oxide as
an indicator were fed at 12-hour intervals at a level of 5. 0 kg per animal each day.
» Minerals were added to the urea ration to approximate the composition of the soybean meal
ration. The steers had access to water and a salt, bonemeal, limestone mixture at all
times. Following a IO-day preliminary period, samples of abomasal contents were collected
through the fistulas once in each 12-hour period for 6 days to provide samples taken at each
` 2-hour interval after both the morning and afternoon feedings. A treatment reversal pattern
was followed so that each steer received each ration during the experiment, providing four
observations per treatment at each time.
The nitrogenous components of abomasal fluid were separated into protein and
nonprotein fractions, the latter being further fractionated into free amino nitrogen, bound
amino nitrogen, purine—pyrimidine nitrogen and ammonia nitrogen. Quantities of each
nitrogen fraction reaching the abomasum were calculated by nitrogenzchromic oxide ratios
relative to intake. The amino acid composition of samples of abomasal contents was
determined after complete hydrolysis by ion-exchange chromatography.
Results and Discussion
The quantities of the different nitrogen fractions reaching the abomasum of steers
fed SBM or urea are summarized in Table l. The values reported are averages of all
times for each treatment and, thus, approximate the composition of abomasal contents
throughout the period from one feeding until the next.
Less total nitrogen reached the abomasum of steers when the urea ration was fed
than when SBM was the supplemental nitrogen source. This indicates that more nitrogen
was being absorbed anterior to the abomasum with the urea supplement than with SBM.
Fractionation of the nitrogen constituents in abomasal contents revealed that the difference
in total nitrogen could be accounted for mainly as protein nitrogen. The quantities of non-
protein nitrogen fractions in the abomasal contents with either nitrogen source were
similar.
Analysis of individual amino acids in abomasal contents (Table 2) did not reveal
differences in the amino acid patterns of proteins and free amino acids that reached the

 -6-
abomasum when SBM or urea was fed. The main difference in the nitrogen reaching the
abomasum in steers fed SBM or urea was quantitative, and this quantitative difference was ·
in the protein nitrogen fraction.
Table 1. -—Nitrogen Reaching the Abomasum of Steers Fed Soybean Meal or Urea
Soybean Meal Urea
% of % of
gm/day ration N gm/day ration N
Nitrogen intake 94. 4 90. 4
Nitrogen in abomasal contents
Total N§/ 73.7 77.6 58.6 65.1
Protein N§./ 37.7 39.7 25.9 28.8
Bound aminoN 19.4 20.4 16.9 18.8
Free aminoN 5.0 5.3 4.8 5.3
AmmoniaN 1.0 1.1 1.2 1.3
Purine-pyrimidine N 3. 4 3. 6 3. 2 3. 5
2/Differences between soybean meal and urea significant (P< 0. 05)
Table 2. ——Essential Amino Acids in Abomasal Contents
of Steers Fed Soybean Meal or Urea (molar
percent)
Soybean Meal Urea
Threonine 6 . 01 6. 31
Valine 7 . 49 7 . 26
Methionine 1 . 93 1. 99
Isoleucine 6 . 06 5 . 93
Leucine 10.48 11.69
Phenylalanine 3 . 83 4. 07
Lysine 5. 89 6.34
Histidine 1.78 1.. 95
Arginine 3. 72 3. 95
PLASMA AMINO ACIDS IN STEERS FED UREA SUPPLEMENTS
C. O. Little, N. W. Bradley and G. E. Mitchell, Jr.
There is a continuing effort in research to develop procedures and methods for ‘
measuring the nutritional adequacy of different rations. This is particularly true for
proteins and protein supplements for ruminants. Results of recent work with non-ruminant
species have suggested that plasma amino acids are influenced by the dietary levels and
thus the quantities available for absorption. In previous reports from this station, results

 -7-
with purified rations in ruminants showed a relationship between amino acids in abomasal
fluid and the free amino acids in plasma. Thus, it was of further interest to study the
amino acids in the plasma of feedlot steers fed different finishing rations supplemented with
_ different sources of nitrogen.
Procedure
Plasma samples were collected from 80 yearling steers at the termination of 133-
and 125-day feeding experiments. The steers received different energy feeds with soybean
meal or urea nitrogen supplements during these feeding periods. In experiment I, 40 steers
were fed ground ear corn with 20 receiving soybean meal and 20 urea supplements. In
experiment II, 20 steers received ground shelled corn at 1%% of the body weight and corn
silage Q libitum and 20 steers received ground shelled corn at 1% of body weight and corn
silage ag libitum. Soybean meal was fed to half of the steers on each corn level, and urea
replaced the soybean meal on an equal nitrogen basis in the rations of the others. Plasma
samples were deproteinized with sulfosalicylic acid, and free amino acid levels were
‘ determined by ion-exchange chromatography.
Results and Discussion
Feedlot performance results of these experiments have been previously reported in
"Animal Science Research Reports-1965" (Ky. Agr. Exp. Sta. Prog. Rept. 150). The
concentrations of each amino acid expressed as micromoles per 100 ml are summarized in
Table 1. On the different energy rations, urea supplements reduced total plasma amino
acid levels 8, 7 and 8%, respectively. The individual amino acids most consistently affected
by substitution of urea for soybean meal were: lysine reduced 12, 19 and 18%; isoleucine
reduced 11, 15 and 12%; valine reduced 10, 14 and 12%; proline reduced 19, 10 and 29%
and methionine reduced 8, 13 and 4% on the respective energy rations.
Table 1. —-Plasma Amino Acid Levels (u mol/100 ml) in Steers Receiving Soybean
Meal (SBM) or Urea Supplements
 
Ear Corn@-/ 1%% Corn+Silgge}2/ 1% Corn+Silage}3/
SBM Urea SBM Urea SBM Urea
Valine 27.1 24.3 34.8 30.0 34.3 30.2
Methionine 2.4 2.2 3.9 3.4 2.7 2.6
Isoleucine 11.6 10.2 13.4 11.4 13.0 11.3
Leucine 22.2 18.8 24.8 22.7 21.4 21.5
Phenylalanine 4.6 5.4 6.6 6.0 5. 9 5. 3 ·
Lysine 15.1 13.3 15.6 12.7 15.1 12.4
Histidine 7.6 8.9 12.0 10.5 9.5 9.5
Arginine 14.5 13.1 8.0 8.7 7.7 8.0
Aspartic acid 3.1 2.7 1.0 0.7 1.3 1.8
Glutamic acid 15.5 15.6 11.8 9.8 10.7 12.5
Proline 18.5 15.0 13.3 12.0 22.0 15.6
Glycine 18.8 16.6 29.7 33.5 30.0 28.8
Alanine 26.0 25.8 27.9 28.7 35.2 31.3
Tyrosine 6.1 4.8 7.4 6.5 7.0 7.0
Total 215 199 230 214 236 218
2/Experiment I, 133 days.
ll/Experiment II, 125 days.

 ..8...
These results suggest that plasma amino acids, both individual concentrations and
total level, are affected by sources of dietary nitrogen. Whether this is a reflection of .
quantity of specific amino acids or total amino acid nitrogen that is passing from the rumen
available for absorption from the small intestine was not determined. However, the
possibility of using these parameters to estimate the nutritional adequacy is encouraged
and is being investigated in greater detail.
SOURCE OF NITROGEN FOR SUPPLEMENTING GROUND EAR CORN
RATIONS FOR FEEDLOT CATTLE - 1966
G. H. Brown, J. R. Overfield, N. W. Bradley and C. O. Little
Previous trials with ground ear corn rations have shown variable results when a
part of the natural protein supplement was replaced with urea. In most experiments gains
have shown a slight depression and additions of trace minerals, alfalfa meal or complex
supplements have not improved feedlot performance. During 1966 this station reported an
experiment in which a slightly greater depression of steer performance was found when
urea replaced all the supplemental nitrogen in ground ear corn rations. However, addition
of 0. 5 lb per head daily of molasses to these urea rations appeared to reduce these de-
pressions until performance was nearly comparable to natural protein sources.
The economic feasibility of using urea in beef finishing rations would be greatly
increased if small inexpensive ration additions could be found that would improve the
efficiency of utilization similar to that of plant proteins.
One hundred and twenty yearling steers, weighing an average of 684 lb, were
divided into replicated lots of 10 steers each to evaluate the following rations:
1. Ground ear corn + soybean meal
2. Ground ear corn + soybean meal + sulfur
3 . Ground ear corn + soybean meal + molasses
4. Ground ear corn + urea
- 5. Ground ear corn + urea + sulfur
6. Ground ear corn + urea + molasses
Urea replaced all the soybean meal on an equivalent crude protein basis in rations
4, 5 and 6. Flowers of sulfur was added at the rate of 0.1% in rations 2 and 5 and molasses
was added to rations 3 and 6 at a rate to provide 0. 5 lb per head daily. The complete
ration composition is shown in Table 1.
All rations were fed to all lots of steers on a free-choice basis during a 119-day
feeding period. Combined soybean meal and urea ration results for the feedlot trial are
summarized in Table 2. The individual ration results are shown in Table 3.
Replacing all the soybean meal with urea significantly decreased average daily gains
by 0.32 lb and feed efficiency by 92 lb per 100 lb of gain. These results are in agreement H
with results reported in 1966 when gains were reduced by 0.29 lb per day and feed `
efficiency by 159 lb per 100 lb of gain when urea replaced all the supplemental nitrogen.
In the current experiment steers consumed significantly less feed per day on urea
rations than with soybean meal rations. These steers also weighed significantly less at

 ...9-
slaughter. However, soybean meal rations produced carcasses with significantly more fat
as demonstrated by a larger percent kidney fat, fat covering the carcass and a smaller
percent of lean cuts.
Table 1. —-Composition of Rations Used in Feedlot Trial
 
Ingredients, lb/ton Ration No.
1 2 3 4 5 6
 
Ground shelled corn 1430 1428 1365 1590 1590 1538
Ground corn cobs 358 358 358 358 358 358
Soybean meal 44% 186 186 204 — - —
Urea 281 - - — 26 26 28
Flowers of sulfur — 2 - — 2 -
Blackstrap molasses - - 46 — - 46
Ground limestone 7.2 7.2 7.2 7.2 7.2 7.2
. Plain salt 20 20 20 20 20 20
2/Vitamin A was added to provide 30, 000 I U per head per day.
W1- Soybean meal
2- Soybean meal plus sulfur
3- Soybean meal plus molasses
4- Urea
5- Urea plus sulfur
6- Urea plus molasses
Table 2. —-Feedlot Performance and Carcass Data of Steers
Fed Two Sources of Nitrogen for a 119-Day Trial
Performance Data Soybean Meal Urea
No. of steers 60 6OI
Initial average weight, lb 685 683
Average daily gain, lb2 2. 233 1.91b
Average daily feed consumed, lb 21 . 73 20.4b
Feed/100 lb gain, lb 976 1068
Carcass Data
Weight at slaughter 9433 905b
· Cold carcass weight2 590 562 _
Percent cooler shrink I . 4 1 . 5
Dressing percent 62. 6 62.1
Percent kidney fat 2. 8a 2. 7b
Marbling score 5. 8 5.7
Conformation grade 13. 6 13. 5
Carcass grade 13.0 13.0
Ribeye area (sq. in.) 11.41 11.25
Fat thickness, in. .533 .46b
Percent estimated retail cuts 50. Og 50.6b
1Average values were calculated for one steer removed
V due to illness.
2Means on the same line not bearing the same superscript
are significantly different. (P< 0. 05).

 ..10-
Sulfur additions to rations 2 and 5 did not appear to contribute any consistent
improvement in feedlot performance or carcass traits. `
Molasses additions to rations 3 and 6 significantly increased ration consumption for
both sources of nitrogen and this would appear to be correlated with average daily gains.
These results are in close agreement with a similar experiment reported by this station in
1966. .
The results of these experiments would seem to indicate urea can be successfully
used as the only supplemental source of nitrogen for ground ear corn finishing rations;
however, steer gains may be reduced by as much as 0.3 lb per head daily.
Additions of molasses to these finishing rations would appear to increase feed intake
and at least partially account for increased steer gains when included in such small amounts.
Table 3. —-Feedlot Performance and Carcass Data Summarized for Steers Fed Two Sources
of Nitrogen With Ration Additions for a 119-Day Trial
Feedlot Data Soybean Meal Urea
1 2 3 4 5 6
No. steers 20 20 20 20 20l 20
Initial av weight, lb 685 688 683 685 680 685 `
Av daily gain, lb 2.133 2.189·b 2.37b 1.79d 1.87Cd 2.07aC
Av daily feed, lb 21.09·d 21.3% 22.9b 19.73 19.32* 22. 2bC
Feed/cwt gain 987 974 966 1098 1030 1074
Carcass Data
Weight at
slaughter, lb 932 937 959 894 896 925
Cold carcass
weight, lb 586 584 602 554 562 570
Cooler shrink, % 1.45 1.49 1.38 1.50 1.38 1.55
Dressing, % 62.9 62.2 62.7 61.9 62.7 61.6
Kidney fat, % 2.8 2.7 2.9 2.7 2.7 2.8
Marbling score 6.2 5.4 5.7 5.5 5.6 6.0
Confor. grade 13.9 13.4 13.5 12.9 13.8 13.9
Carcass grade 13.5 12.5 13.0 12.6 13.2 13.3
Rib eye area
sq. in. 11.26 11.70 11.26 11.33 11.27 11.16
Fat thickness, in. . 57 . 45 .57 . 44 . 41 . 53
Est. retail cuts, % 49. 7 50. 8 49. 5 50. 8 -50. 9 50. 0
lAverage values were calculated for one steer removed from experiment due to illness.
2Means on the same line not bearing the same superscript are significantly different.
(P< 0 . 05).

 ..11-
VITAMIN A TURNOVER IN STEERS FED U
, ADEQUATE VITAMIN A
B. W. Hayes, G. E. Mitchell, Jr. and C. O. Little
A study reported in "Kentucky Animal Science Research Reports-1966" (Ky. Agr.
Exp. Sta. Prog. Rept. 164) indicated that liver vitamin A reserves in sheep are in a
dynamic state, even when the animals are receiving adequate dietary vitamin A. Average
half-time for tritium-labeled vitamin A in livers of six ram lambs receiving alfalfa hay
and corn was estimated to be 75 days. The results reported here are from a similar
experiment using steers .
Procedure
A Six Hereford steers, averaging 170 kg, each received jugular injections of tritium-
labeled vitamin A acetate. Daily rations consisted of alfalfa hay and minerals fed free
choice and 1.4 kg of ground shelled corn supplemented with 10, 000 I. U. of vitamin A
palmitate per steer. Liver samples were taken by aspiration biopsy on the 9th day after
treatment and then at 3-week intervals. Jugular blood was sampled at the time of each liver
biopsy, and feces and urine were collected for a 24-hour period immediately prior to each
liver biopsy.
Liver samples were saponified with alcoholic potassium hydroxide and these along
with serum samples were extracted with petroleum ether. Vitamin A was then determined
with trifluoroacetic acid, and tritium activity was determined with a liquid scintillation
counter.
Results and Discussion
Average tritium activities of daily eliminations of urine and feces are shown in
Table 1. Similar amounts of tritium activity were excreted in the urine and in water soluble
products of the feces. Considerably less activity was recovered from the ether extractable
portion of the feces, and only trace amounts of tritium could be detected in either the water
or ether extracts of the feces 72 days after treatment.
Table 1. —-Tritium Activity (105DPM) Recovered- From
Daily Excreta of Steers
 
Feces
Day Urine Ether Extract Water Extract
 
9 50 6 73
30 21 1 15
51 11 1 10
7 2 7 - -—
93 6 — —-
 

 ..12-
Liver and serum data are presented in Table 2. While the concentration of vitamin
A in the liver was relatively constant, tritium activity decreased with time. This apparent `
continuous decrease in tritium activity of the liver and the detection of tritium in the blood
throughout the trial provide strong evidence of continuous turnover of vitamin A stores.
From the specific activity of vitamin A given in Table 2, the half-time for vitamin A in the
liver of these steers is estimated to be 49 days, which is somewhat less than the half-time
of 75 days estimated previously for sheep. .
Table 2. -—Vitamin A and Tritium Activity of Liver and Serum of Steers
Liver Specific Activity Serum
Liver Tritium of Liver Tritium
Vitamin A Activity Vitamin A Activity
Day (Meg/gm) (103DPM/gm) (102DPM/mcg) (10 DPM/mi)
9 62. 2 229 41 28
30 55 . 4 175 29 14
51 59. 5 137 23 7
7 2 60 . 1 102 17 4
93 59. 4 80 13 4
INFLUENCE OF LOW DIETARY PROTEIN ON VITAMIN A
TURNOVER IN STEERS
B. W. Hayes, G. E. Mitchell, Jr. and C. O. Little
The level of dietary protein has been reported to influence the status of liver vitamin
A reserves in most animals studied. Dietary protein deficiency usually decreases the
storage of vitamin A in the liver and increases the rate at which stored vitamin A is
depleted. Protein is also known to be involved in normal vitamin A transport. These
observations suggest that protein status may affect the turnover rate of vitamin A stores.
The present study was designed to test the possible influence of low dietary protein on the
turnover of vitamin A in the liver of steers.
Procedure
Six Hereford steers with previously established hepatic stores of tritium-labeled
vitamin A were randomly divided into two groups. The steers averaged about 240 kg and
each received 5. 4 kg of feed daily. During the first 56-day trial, steers in group I
received a ration (52% corn and 48% cobs) containing 6% crude protein; those in group II
received a ration (17% soybean meal, 35% corn and 48% cobs) containing 12% crude protein.
The rations were supplemented with sufficient vitamin A palmitate to maintain the steers'
liver vitamin A reserves, and the steers had free access to minerals. The study involved
four trials. Prior to the second, third and fourth trials, the rations were reversed.
Sampling and analytical procedures were similar to those described in the preceding paper.
Results and Discussion
Excretion of tritium activity was mainly through the urine. Only traces of radio-
activity could be detected in fecal samples during the first trial and none was detected

 ..13..
· during the second, third and fourth trials. Average tritium activity of the daily excretion of
urine is presented in Table 1.
Table 1. -—Average H3-Activity (105 DPM) of Daily Urine
Excretion of Steers Receiving Rations Containing
6% or 12% Crude Protein
Ration
Trial 6% Crude Protein 12% Crude Protein
I 4 5
II 4 2
III 3 4
IV 1 1
_ Average vitamin A and tritium activity of serum samples are given in Table 2.
A Vitamin A in the serum remained relatively stable, whereas tritium activity declined for
both treatments. This would be expected in view of the continuous decline of labeled vitamin
A in the liver. Treatment did not significantly alter total plasma protein, plasma albumin
or plasma globulin fractions.
Table 2. -—Average Serum Vitamin A and H3—Activity of Steers
i Receiving Rations Containing 6% or 12% Crude Protein
Ration
6% Crude Protein 12% Crude Protein
Vit A DPM/ml Vit A DPM/ml
Trial (mcg/ ml) (mcg/ ml)
I 0 . 58 313 0 . 51 302
II . 49 82 . 52 89
I I I . 48 31 . 54 50
IV . 46 23 . 50 17
Half-times for labeled vitamin A in livers of the steers are shown in Table 3. Steers 4
receiving the ration containing 6% crude protein appeared to exhibit a longer half—time for
vitamin A in the liver tha.n steers on the 12% crude protein ration; however, the difference
was not statistically significant.
When the actual values for different treatments are compared with each other and
with the values presented in the preceding report, it is apparent that the turnover rate for
vitamin A in the liver of steers is highly variable. Within the limits studied, differences
in protein intake do not appear to account for a major portion of this variation.

 -14-
Table 3. -—Average Half-Times (Days) for H3-Labeled -
Vitamin A in Livers of Steers Receiving Rations
Containing 6% or 12% Crude Protein
 
Ration
Trial 6% Crude Protein 12% Crude Protein `
 
I 36 53
II 80 65
III 108 78
IV 160 155
Average 96 88
 
EFFECT OF VITAMIN E ON PRE-INTESTINAL
DISAPPEARANCE OF VITAMIN A .
R. L. Warner, N. E. Alderson, G. E. Mitchell, Jr. and C. O. Little
Results of previous experiments have indicated that there may be considerable
destruction of the ingested vitamin A before it reaches the small intestine. The usefulness
of vitamin E in protecting vitamin A from oxidative destruction in feeds suggests that it
might be useful in reducing pre-intestinal destruction. This report gives the results of an
experiment conducted to study this possibility.
Procedure
Three mature steers previously fitted with permanent abomasal fistulas were used _
in a multiple switch—back experiment with each steer receiving each treatment twice. Each
steer was fed 5 kg daily of a ground mixed ration containing 20% shelled corn, 76% alfalfa
hay, 3% animal fat, and 1% salt and minerals. A 2-week preliminary period was followed
by recovery trials at 1—week intervals.
Pre—intestinal destruction of vitamin A was estimated by administering approximately
1, 000, 000 I U of vitamin A acetate dispersed in 20 ml of 20% aqueous Tween "80" and 20 gm
of chromic oxide in a gelatin capsule with or without 40, 000 I U of vitamin E. Twenty—four
hours after dosing, abomasal contents were collected through the abomasal fistula and
analyzed in triplicate for vitamin A and chromic oxide. The change in the ratio of chromic
oxide to vitamin A from the ratio administered was used to estimate the percentage of
administered vitamin A reaching the abomasum.
Results and Discussion
Table 1 gives the calculated pre-intestinal disappearance of vitamin A. As previously
observed, a major portion of the administered vitamin A disappeared before reaching the
abomasum. Results for individual steers and individual periods were highly variable. How-
ever, the data give no indication that high levels of supplemental vitamin E significantly
affected the vitamin A disappearance. This suggests that ruminal destruction of vitamin A
may not be an oxidative process.

 ..15-
‘ Table 1. ——Pre-Intestinal Disappearance of Vitamin A, in Percent
Steer Vitamin A Steer Vitamin A and
Week Number Only Number Vitamin E
1 13 53 . 4 17 66. 2
2 17 73 . 2 21 55. 2
3 21 51 . 2 13 44. 7
4 21 57 . 1 13 64. 4
5 17 40 . 7 21 49 . 3
6 13 85. 2 17 81. O
Average 60.1 60.1
EFFECTS OF THIABENZOLE, INJECTABLE VITAMIN A AND
LEVEL OF DIETHYLSTILBESTROL IMPLANT ON STEER PERFORMANCE
D. B. Laster and N. W. Bradley
The objective of this feedlot trial was to determine the effects of vitamin A,
thiabenzole and 24 versus 36 mg of diethylstilbestrol on the average daily gains of steers.
Twenty-four Angus steers were group fed free-choice alfalfa silage with ground ear I
corn added at the time of ensiling. Enough additional ground shelled corn was fed to give
approximately 8 lb of shelled corn per head per day. All steers received 10, 000 I U of
vitamin A daily in the salt and also received steamed—bone meal and water free—choice.
The salt and vitamin A were changed every 7 days to prevent loss of the vitamin.
The steers, averaging 704 Ib each, were randomly allotted, afterblocking for weight,
to eight treatments in a 2 x 2 x 2 factorial arrangement with 3 steers per treatment.
The primary treatment comparisons were; 24 or 36 mg DES; 1 million I U vitamin A
intramuscularly or no vitamin A; and three thiabenzole boluses or no thiabenzole. The
steers were subjected to these treatments at the beginning of the trial.
During the 155-day feedlot trial individual steer weights were taken every 28 days. ,
The steers were individually weighed on and off the experiment after a 12-hour shrink off
feed and water.
Each group of steers received one of the following treatment combinations: