TEXAS AGRICULTURAL EXPERIMENT STATION
A. B. CONNQZERECTOR,
‘IVOEEWUIC: , 

T’ OLLEGE _
BULLETIN N0. e59 OF fiQIXrQEMBER 1944

SORGHUM SILAGES AND DEHYDRATED ALFALFA
LEAF MEAL AS SOURCES OF CAROTENE IN
BEEF CATTLE FATTENING RATIONS

J. H. JONES, J. M. JONES, G. S. FRAPS,
A. R. KEMMERER, R. E. DICKSON,
C. E. FISHER AND N. R. ELLIS

Division of Range Animal Husbandry

 

AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS
GIBB GILCHRIST, President

E17-944-4M-L1 80

[Blank Page in Original Bulletin]

Carotene as contained in dehydrated alfalfa meal was
apparently better utilized for vitamin A activity than carotene
in either sweet sorghum or grain sorghum silage. Carotene
as contained in the two sorghum silages seemed to be about
equally utilized. Sweet sorghum silage such as sumac or red
top cane silage contained approximately twice as much car-
otene as the grain sorghum silages such as kafir, milo, and
hegari silage. The dehydrated alfalfa leaf meal contained
much more carotene than the sorghum silages.

Night blindness occurred when levels of ab0ut2000 __IIliQLQ;__\\

gramswof carotene daily per 100 pounds live weightwere sup-
plied regardless of source. At the same levels steer__calves of 330
pginds initial weight showed higher degree of night blind-
ness than steer yearlings of 570 pounds initial weight. Steer
calves became depleted of vitamin A reserves more quickly
than yearling steers, as indicated by the earlier appearance
of night blindness. Thisjndicated that young cattle may need
somewhat larger amounts of i“?cagterfiidrrwisual-fattening
periods than older cattle largely because they are likely to
have lower reserves of vitamin A than the older cattle.

The work indicates that sorghum silages when fed as the
sole roughage in fattening rations for cattle may be expected
to protect the animals from the effects of vitamin A de-
ficiency for feeding periods of about 200 days. Approximately
one pound of good quality sweet sorghum silage fed daily per
100 pounds live Weight may accomplish protection but 2 to
3 pounds of grain sorghum silage may be necessary to
secure the same result.

\

‘CONTENTS

PAGE
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Cattle . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -. . . . . . . . . . 6

Feeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T

Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '7

Sampling Feeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Carotene and Moisture Content of Feeds . . . . . . . . . . . . . . . . . . . . . . .. 9

Carotene Intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

Average Rations Consumed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11

Feedlot Gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15

Night Blindness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15

Carotene Content of Plasma and Livers . . . . . . . . . . . . . . . . . . . . . . . .. 17

Condition of Steers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23

Marketing and Slaughter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26

SORGHUM SILAGES AND DEHYDRATED ALFALFA LEAF MEAL
AS SOURCES OF CAROTENE IN BEEF CATTLE
FATTENING RATIONS

J. H. Jones} J. M. Jones,'—' G. S. Fraps," A. R. Kemmerer} R. E. Dickson,‘
C. E. Fisher“ and N. R. Ellis?

Texas Agricultural Experiment Station and Bureau of Animal Industry,
United States Department 0f Agriculture, cooperating.

Dehydrated alfalfa leaf meal, the better grades of alfalfa hay, and green
forages are excellent sources of carotene for cattle. While such feeds
vary widely in carotene content, only small amounts are required in
fattening rations to prevent vitamin A deficiency. Silages also contain
carotene in varying amount, but their vitamin A potency may be low
as shown by the occasional occurrence of vitamin A deficiency among
cattle fed silage as the principal roughage in fattening rations (1).
Such deficiency has been observed when the carotene content of the
silage would indicate according to the results secured from the use of
alfalfa as a source of carotene (2) that the cattle were receiving
sufficient carotene to prevent vitamin A deficiency. It has been reported
by Ward, et al., (3) that the adequacy of the carotene depends upon
the source of carotene and that higher levels of carotene are necessary
to prevent vitamin A deficiency when the carotene is supplied by silage
than when it is supplied by alfalfa.

Recent work by Kemmerer and Fraps (4, 5) has shown that the crude
carotene as currently determined contains impurity A, neo-beta-carotenes
B and U, in addition to beta-carotene. The crude carotene of dehydrated
alfalfa may contain from 26.4 to 75.3 per cent of beta-carotene (4); The
crude carotene content of sumac silage contained, on an average, 51%
of impurity A, 14.2 and 5.9% respectively of neo-beta-carotenes U and B,
28.9% beta-carotene and had a beta-carotene equivalent of only 31.8% (6).

The work reported here was planned to gain information on silages as
sources of carotene and to determine the comparative value of carotene
from dehydrated alfalfa leaf meal, sweet sorghum silage and grain
sorghum silage.

_ ‘Animal Husbandman, T.A.E.S.

A "Chief, Division of Range Animal Husbandry, T.A.E.S.

sChief, Division of Chemistry, T.A.E.S.

‘Chemist, T.A.E.S.

‘Superintendent, Substation No. T, Spur, Texas, T.A.E.S.
"Agronomist, Substation No. T, Spur, Texas, T.A.E.S.

‘Principal Chemist in Charge Animal Nutrition Investigations, Bureau of Animal In-
dustry, U.S.D.A.

s BULLETIN NO. s59, TEXAS AGRICULTURAL EXPERIMENT STATION
PROCEDURE

The materials compared were fed to separate groups of steers in fattening
rations to supply approximately 2000* micrograms of carotene daily
per 100 pounds live weight. At this intake, a slight degree of night
blindness is expected when dehydrated alfalfa leaf meal is used as the
source of carotene (2). Three groups of steers were fed for 196-day
periods during each of the 1941-42 and 1942-43 feeding seasons. Three
criteria were employed to determine the relative value of utilization
of carotene from the different sourcesz. (a) the length of time required
for night blindness to occur, (b) the degree of night blindness, and (c)
the carotene and spectro-vitamin A content of livers and the carotene
content of blood plasma.

In both years 30 head of Hereford feeder steers were divided as equally
as possible into three groups of 10 head each. They were weighed
individually on three consecutive days at the start and at the close of the
experiment and single individual weights were taken at weekly intervals.
The average of the three weights taken at the start and at the close
formed the respective initial and final weights.

In the first year the steers were fed individually, but in the second
year they were fed in groups. The steers received a basal mixture of
feeds low in carotene to which the carotene supplements were added.
They were fed as much total feed as they would consume twice daily.

Tests for night blindness were begun after 60 days and were then con-
tinued at weekly intervals. The tests for night blindness were made
and the degrees of affected vision were measured according to procedure
developed in previous work (2). With certain modifications as plus and
minus signs the symbols used in recording the observations were as follows:

O—No indication of night blindness.

S—A suspicion of night blindness.

1—Cautious, can see objects 5 feet away.

2—Cauti0us, slow to move but can see objects when close upon them.
3~Cannot see, will bump into obstructions.

In averaging observations, numerical values were assigned to the
symbols as: $2.3; 1.—:.7; 121.0; 1+:1.3; etc.; with 3:30 or
night blind.

Blood samples for plasma, carotene and liver samples from some of
the steers were secured in each year for chemical analysis. Samples of
the feeds used as sources of carotene were collected at 14-day intervals
for the determination of carotene and moisture.

Cattle: The 30 head used in 1941-42 were the heaviest ones in a
group of 104 weaned Hereford steer calves received at the Station feedlot
November 18, 1941. They were uniform in type, were 5 to 6 months of age

and averaged 330 pounds, ranging in weight from 301 to 360 pounds

*An intake of 2000 micrograms daily per cwt., was attempted but the intakes varied,

as explained under Carotene Intake.

SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 7

when started on test December 3, 1941. From November 18 to December
3, they were given a full feed of sumac silage and one pound of cottonseed
meal daily per head. Two weeks after start of test, they were treated with
phenothiazine for stomach worm infestation. A representative group of
the calves is shown in Figure 1.

Figure 1. Representative group of feeder steer calves used in 1941-42.

Thirty Hereford yearling steers averaging 570 pounds at the outset
were used in 1942-43. These steers had been maintained largely on Station
pasturage since their purchase as calves in November, 1941. The thirty
"head were carefully selected from a group of approximately '70 head and
were quite uniform and thrifty.

Feeds: Dehydrated alfalfa leaf meal was secured from the same milling
company in both years. Cottonseed meal of 43 per cent protein content
was purchased locally. The milo heads used in 1941-42 and the threshed
milo used in 1942-43 were locally grown and were of good quality. The
sweet sorghum (sumac) silage was of goodgquality in both years. The
grain sorghum silage used in 1941-42 was kafir and milo. That fed for
the first 126 days was mostly kafir, while that fed during the last
70 days was mostly milo. The milo silage was of poor quality but the
kafir silage was of good quality. The hegari silage used in 1942-43 was
from an excellent, well matured crop, which afforded a silage of high
quality. All of the silages were stored by usual methods in trench silos.
Figure 2 shows a wagon load of 1942 crop hegari bundles.

Feeding: In the 1941-42 experiment Group 1 received dehydrated alfalfa
leaf meal as the source of carotene; Group 2, grain sorghum silage as
already described; and Group 3, sweet sorghum (sumac) silage. Similar

8 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

sources of carotene were used in 1942-43 except for Group 2, which received
hegari as the grain sorghum silage.

The steer calves used in 1941-42 were fed individually. They received
a basal mixture of cottonseed meal, ground milo heads and cottonseed hulls.
At the start this mixture consisted of 1O per cent cottonseed meal, 10
per cent ground milo heads and 8O per cent cottonseed hulls. The per-
centage of concentrates was gradually increased until the mixture con-

Figure 2. Hegari harvested October 1, 1942, and preserved in the trench silo for the
194-2-43 experiment.

sieted of 15 per cent cottonseed meal, 50 per cent ground milo heads and
35 per cent cottonseed hulls. One-tenth pound each of granulated salt
and pulverized oyster shell was added to the daily feed. The calves
were fed as much of the basal mixture as they would consume twice daily,
in addition to the specified carotene feeds.

The yearling steersvused in 1942-43 were group fed. Equal amounts of
dry matter were fed in so far as possible to each of the three groups.
Three pounds of cottonseed meal were fed daily per head as soon as the
steers could be placed on feed. A maximum of 5 pounds of ground threshed
milo was fed daily per head. All groups received the same amount of
concentrates. The silages and dehydrated alfalfa leaf meal fed as sources
of carotene were mixed with the other feeds. Pulverized limestone, 0.1
pound daily per head, was mixed with the feeds. Granulated salt was
supplied as a lick. a

SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 9

Sampling Feeds: Samples of feeds were taken at 14-day intervals for
carotene analyses. When received, the supply of dehydrated alfalfa leaf
meal was divided into numbered lots and stored in a dark room. The
first sample was drawn from Lot 1 and this lot 0f meal was fed until
an analysis was secured of the next lot. Two representative samples of
each silage were drawn from the exposed cross section of the trench silo,
one for carotene analyses and the other for moisture. The samples used
for carotene analyses were preserved in methanol. In the first year the
samples of silage were sealed immediately after they were drawn from
the silo. In the second year the samples were drawn in the afternoon and
were then held until the next morning before sealing. The latter procedure
afforded samples more representative of the silage as it was fed.

RESULTS

Carotene and Moisture Content of Feeds: The crude carotene was de-
termined by the A.O.A.C. Method ('7) and the pure carotene was de~
termined by shaking the crude carotene with magnesium carbonate as
(lescribed by Kemmerer and Fraps (8). The analyses for pure carotene
and moisture of the materials used as sources of carotene are shown in
Table 1.

The carotene content of the silage declined in general from start
to close of the experiment in 1941-42. The 1942-43 silages varied through-
out but did not show progressive decline in carotene content. The silages
from the 1942 crop fed in 1942-43 averaged higher in both carotene and
dry matter than the silages from the 1941 crop fed in 1941-42. As a
result they had a higher carotene value per pound, as shown in Table 1.
The average carotene content of the silages for two years indicate that
sweet sorghum silage contained approximately twice as much carotene
per pound as grain sorghum silage although containing approximately
10 per cent more moisture.

Carotene Intake: The values for carotene and moisture shown in Table
1 were used to determine the daily allowances of dehydrated alfalfa
leaf meal and of the silages used as sources of carotene. Adjustments
in the allowances were made each week upon the basis of steer weight,
the carotene content of the dehydrated alfalfa leaf meal, and the carotene
and dry matter content of the silages.

The time required for analyses caused the allowances to be controlled
by samples which were collected 2 to 4 weeks earlier. Because of variations
in carotene content between samples in some instances twice as much
silage was fed during some weeksythan was fed in others. With this
situation recalculations were made upon the basis of samples drawn at
nearest dates to actual feeding. For example, in the 1942-43 experiment
the allowances fed were based on the samples collected December 11,
but the carotene intakes as recalculated were based on the samples of

10 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

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SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 11

January 3 and 19. Table 2 shows the values for pure carotene and dry
matter which were used in recalculating the carotene intakes and which
are shown in Table 3.

Table 2. Average values for pure carotene and dry matter used in recalculating
carotene intakes

Carotene Mcgr. per gram
Samples used Dry Basis Dry Matter %
Periods of Date o_f _
Time of collection Dehyd. Sweet Gram Sweet Grain
Alfalfa Sor hum Sor hum Sor hum Sor hum
Leaf Meal Si age Si age Si age Si age
1941-42
Experiment
12/ 3-12/31 12/8,12/22, 1/5.... 276.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
12/ 3-12/31 11/17,12/8, 12/22,
1/5 . . . . . . . . . . . . . . . . . . . . . .. 36.18 20.18 26.55 34 26
12/31- 1/28 1/5, 1/19, 1/31  261.8 23.40 11.53 24.40 32 03
1/28~ 2/25 1/31,2/14,3/2..... 265.3 17.67 7.20 26.30 3O 43
2/25- 3/25 3/2, 3/28 . . . . . . . . . . 259.5 20.35 3.55 26.29 33 80
3/25~ 4/22 3/28,4/11,4/25.... 243.0 29.13 3.60 25.46 37 34
4/22- 5/20 4/25,5/9,5/29..... 208.3 18.70 2.87 24.25 36 39
5/20- 6/17 5/29, 6/6 . . . . . . . . .. 194 0 11.35 1.55 25 62 36 48
1942-43
Experiment
11/11-12/9 12/11 . . . . . . . . . . . . . . . . . . . . . .. 46.00 5.90 27.34 39 32

12/ 9-12/30 12/1, 1/3 . . . . . . . . . . . . . . . . . . .. 39.30 8.40 26.58 38 69

12/30- 1/20 l/3,1/19 . . . . . . . . .. 141.5 37.50 11.40 28.31 38 70

1/20- 2/ 3 1/19, 242 . . . . . . . . .. 140.0 33.50 11.75 32.04 38 91

2/ 3- 2/24 2/2, 2/ 1 . . . . . . . . .. 144.0 21.70 9.85 31.69 39 35

2/24- 3/ 3 2/21, 3/9 . . . . . . . . .. 149.5 31.35 13.80 30.67 34 02

3/ 3— 3/31 3/9, 3/31 . . . . . . . . .. 138.0 39.65 12.10 27.87 38 25

3/31- 4/21 3/21, 4/18 . . . . . . . .. 130.0 28.85 8.45 25 12 44 27

4/21— 5/12 3/31 . . . . . . . . . . . . .. 130.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

5/12- 5/26 4/26,5/7 . . . . . . . . .. 134.0 33.80 13.20 25.17 38.92

The average intakes of pure carotene for each group is shown in Table
3 by designated feeding periods. In 1942-43 compared intakes of carotene
from the different sources were not started until the eighth week of feeding;
however, the average carotene intakes for the first seven weeks are shown.

The average carotene intakes supplied Group 1, which received de-
hydrated alfalfa leaf meal, were rather constant between feeding periods;
but there was much variation in the intakes for Groups 2 and 3, receiving
the silages. This variation for Groups 2 and 3 reflects the variation in
carotene content between succeeding samples of the silages.

Average Rations Consumed: The average rations consumed and the
gains in pounds for designated feeding periods are shown in Table 4 for
both experiments.

There was considerable variation in consumption of the basal feed
mixture between groups in 1941-42. Only small amounts of dehydrated
alfalfa leaf meal were required to supply an intake of 2000 micrograms
of carotene but comparatively large amounts of the silages were required.
As more silage was fed, less of the basal mixture could be consumed.
Group 2, receiving grain sorghum silage, consumed the least amount of

12

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U
O
S

 

14 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

JGOET~OQK@  G@ SuOQ wmww  m0 M. UOTHUQ UGN 99am.  m0 N UOiUhm aQQOKQ mummy  a0 0&0; MUOMhQQ 

Ea o»; ao a Ea 2w H 2a wma aha . . . . . . . . . . . . . . . . . . . .55‘ 2E. wwws><

§m » . . . . . . - . . . . . . . . - . - . . . . ~ ' . . . . . . . ¢ 4 . . . . . - . . . . . . . . - , .  . N  . . . . . . . . . . . . . . . . . . 1 - . -   

3e owh 3a hmh owh 8a ohh hoh . . . . . . . . . . . . . . . ....;..w@=w Eiomxa Hmsaw

hoh~ hNBH QT: 9:: hhhfi 3X: oi: a2: . . . . . . . . . . . . . . . . . . . . . . . 121E hovwcofioU

“oh ooh ooh oo.h oo h ooh ooh main . . . . . . . . . . . . . . . . . . . . . . . 113E uuomcofioU

:4. oo.h oo.h ooh oo.h oaa oo.h ha; . . . . . . . . . . . . . . . . . . 19:5 wmimfifi 32.6
dcooobau oo 355w
mm vmazm flowEswo Esnwhom oQoRm h Q5050
aaa 2.. o hh n aaa E a hhh oh. a 3a . . . . . . . . . . . . . . . . . . dam 2% wwwhv><

hwh S. I a» aw M52 ao h .3. I 3a EM . . . . . . . . . . . . . . . . . . . . dmmmw Eshmhow c650

$€.@ . . . . . . . . . . . . . . . . . . . . . . . . . . . - n u . . . . . . . . . . . . . . . . . I . .   . . . . . . . . . . . I . . . . . . 4 .   

No.3 omi oo 2 32 ho 3 hmhfi 8.5 2.2 . . . . . . . . . . . . . . . . . . . . . . . 221E wmawgaficu

“oh oo.h oo h ooh oo h ooh ooh onh . . . . . . . . . . . . . . . . . . . . . . . 213E woowcofioU

:4. ooh oo h ooh oo h omé ooh am. . . . . . . . . . . . . . . . . . . . .21: @2335 vcsobw
dcvoobwo oo v0.50.“
mm @926 Qbwmonv EDGMuOm CEBU .N Quobw
baa 8.. an a 8a 8 _ Ea 2 .a fia . . . . . . . . . . . . . . . . . . . . 3% 2E. Qwfiwia

§m. . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . . . . . . . . . .  .w&_. . . . . . . . . . . . . . . . . . . . . .Q@.N.ZW Emwgxhow 

 . . . . . . . .    . .   . . . . . . . . . . . . . . . . . . . Ivmflfimsflfiwhnomuvvgw

om. oh. on. hm. ha. hm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . .  .135 om“: n23?

if: hhhfi 2K: 9K: 21: 21: Q1: a_ .2 . . . . . . . . . . I. . . . . . . . . . . 121E wmawaofiou

noh ooh ooh ooh ooh ooh ooh Emu  . . . . . . . . . . . . . . . . . . . IRoE woowcooooU
IQ ooh ooh ooh ooh oaa ooh “N;  wwfioz: E580
dawoobao no
unison ma _NQE F2 minim ufimhwzsufl A asgU
wmczpmoh 53w hi? ocoiioaxm hfiflmwofi
h o h a. h N fi
was“. 2: “fizz
oma~v>< ulooflom
woE-Scewlweion .3 3:52- E ma?» can 2:52- 5 uoiamnao 283E omu~o>< é oEah

  
   
   
   
  
  
 
   
   
 
 
   
  
   
   
   
   
   
   
   
 
   
  
 
 
 
  
  
  

SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 15

3- basal mixture. Group 3, although fed from 2 t0 10 pounds of sweet
'~ hum silage throughout, had strong appetite and consumed almost
1 much of the basal mixture as Group 1 which received small amounts
j the dehydrated alfalfa leaf meal.

_In 1942-43, the steers were full fed and were fed similar amounts of
ncentrates. The rations were kept adjusted to a full feed by use of
 ing amounts of cottonseed hulls. For example Group 2, which received
T considerable amount of grain sorghum silage, was fed a smaller amount
 cottonseed hulls than Groups 1 and 3. Group 3 ate the morning feed
Lich contained the daily allowance of silage more readily than the
 ning feed. Group 1, receiving dehydrated alfalfa leaf meal, was usually
wer in eating than Groups 2 and 3.

"Feedlot Gains: The average weights of the three groups of steers used
k 1941-42 and 1942-43 are shown in Figure 3.

In the first experiment Groups 2 and 3 fed the silages as sources of
 tene had the advantage in gain over Group 1 which received dehydrated
alfa leaf meal as a source of carotene. Near the close of the first
g ~ riment Group 2, fed grain sorghum silage showed symptoms of advanced
 min A deficiency as complete night blindness, staggering and rapid
ppiration. The group also showed a decline in appetite and gain during
 last 5 weeks. Groups 1 and 3 were not as severely affected. In the
 0nd experiment Group 1, receiving alfalfa had the advantage in gain and
ne of the groups were seriously affected by vitamin A deficiency, although
' 1 t blindness appeared.

i. Night Blindness: Tests for night blindness were conducted at weekly
gtervals after the steers had been on feed about 60 days. In the 1941-42
'eriment, night blindness was observed after the calves had been in
' ~ lot for 111 days. The night blindness appeared suddenly and uniformly
7 all groups, the range between individuals being 16 days. Night blindness
creased in all groups rapidly, but most rapidly in Group 2, which
* ived grain sorghum silage as the source of carotene. During the final
ervations, June 17-19 or approximately 102 days after the first ap-
 ance of night blindness all of Group 2 steers would blunder about
dly. Steers in Groups 1 and 3 while night blind, still retained some
se of perception and would avoid familiar obstacles.

In the 1942-43 experiment with yearling steers there was evidence
 night blindness after 101 days in dry lot, but it was not appreciable
 all groups until after 136 days. After 136 days there was a definite
3w ase in night blindness in Group 3, fed sweet sorghum silage, and
fislight increase in Groups 1 and 2. At the close on May 26, Group 1,
iving dehydrated alfalfa leaf meal as the source of carotene showed
Q- least night blindness and Group 3 showed the most while Group 2
 iving grain sorghum (hegari) silage was intermediate. No steers
__ me completely night blind and there was much less night blindness
 ughout than for the steer calves used in 1941-42.

 

16 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

dwsmaw

.m QEZU

.65: coficw

.2: .53

A Q5910

 

  
  
 
   
 
  
  
   
  
   
   
  
   
   
 
  
  
  
    
    
   
   
   
 
   
  

SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 17

Carotene Content of Plasma and Livers: In the 1941-42 experiment
blood samples for carotene analyses were drawn at the outset, after 73
days and 110 days; also at the close, or after 196 days, except for
roup 2, fed grain sorghum silage as the source of carotene. Liver samples
ere also secured from Group 1, fed dehydrated alfalfa leaf meal as
urce of carotene, and from Group 3, receiving sweet sorghum silage
source of carotene.

In the 1942-43 experiment, blood plasma samples were drawn after
55 days and at the close, also liver samples were secured from all
 oups. The carotene content of blood plasma and the carotene and
l ctro-vitamin A content of livers and the average of 2 observations of
"ght blindness at the approximate date blood samples were drawn are
“liown in Table 5. The spectro-vitamin A was determined by methods
*‘-- cribed by Fraps and Kemmerer (9).

}At the outset of the first experiment, the average carotene content
 the blood plasma of 9 calves, 3 calves being selected at random from
 h of the three groups, was 1.58 ppm. At this time the calves had
-- in dry lot for approximately two weeks on sweet sorghum silage
J cottonseed meal. The ‘plasma samples for February 14 or 73 days
ter, from 5 head in each group including the steers first sampled,
leraged .56 ppm. of carotene for Group 1; .34 ppm. for Group 2, and
Y» ppm. for Group 3. The greatest decline of plasma carotene had occurred
i Group 2 and the least in Group 3. Night blindness was not evident
l; this time; but two steers in Group 2 showed only .22 ppm. plasma
 otene while later on steers which were completely night blind showed
l her values.

 plasma samples collected in the first experiment on March 23, 1942,
 after 110 days, averaged .49, .30, and .35 ppm. plasma carotene for
 respective groups. As compared to the values found in February or
 days earlier, Group 3 lost .30 ppm. carotene or nearly 50 per cent but
 loss was small for Groups 1 and 2. At this time all groups showed
l‘ appreciable degree of night blindness, although night blindness had
been evident in any individual more than 14 days. At the close,
‘in 18, Groups 1 and 3 averaged .37 and .28 ppm. plasma carotene.
= e out of nine steers in Group 1 and seven out of nine in Group 3
Q completely night blind. As compared to the plasma carotene values
i d in March or 86 days earlier there was a 25 per cent loss of plasma
‘tene in Group 1 and a 20 per cent loss in Group 3. i

_roup 1 livers averaged .71 ppm. carotene and 1.59 ppm. spectro-
 in A while the respective values for Group 3 were .62 and 1.79.
ire was greater variation in Group 1 than in Group 3 in carotene
tent of livers and of blood plasma. Samples of plasma taken at the
 for Group 1 show a distinct separation. Five samples averaged
 ppm. carotene while four averaged .53 ppm. The five steers which
f- low in plasma carotene averaged .63 ppm. carotene in livers and

18 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

c4... c; c; av. m»... cw. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mm

o6. 0d m; 3. vm. Q. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mm

5m mo. ab. ow. ~N. E. mw. mo; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ImQ

mwd m. o; R. Hm. Si . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . mo

. . . . . . . . .. mo;   wwvu m6. 
65:33 Ho 03:3

mm owwzw A3553 Esnmhom fiEBm .m .5050
@.$  . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..OWnw-MU><

o5 Nfi . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. S. 

o5 9m . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. hm. av. EWN 

o5. mmfi . . . . . . . . . . . . . . . . . . . . . . . . . . . . I mm mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

oh mTm . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AK

04m o.w . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. mm. mm ow; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. §

o5 w; . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. flu ma. on; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zww

o6 m; . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mm

o6 o; . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inw

ck. nw. . . . . . . . . .. . . . . . . . . . . . . . . . . .. mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iom

o5 m. . . . . . . . . . . . . . . . . .  . . . . . . . . .. on. om. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Imw
dcfiohwu “o 355m mm

umwmm 3:5 was hind EUJMQOm c850 .m Q5910
   7      . . . . . - . . . - ¢ . . . . . . . . . . . . . - . . . . 

o5 mo; HA mm. mm. mm aw. “m; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z2

o5 mfim m.“ aw. mm. on mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10w

oh o; A; an. an. om. mm. ow; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I5

mw.w m?“ o; aw. wm. um. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iww

5m n; o; aw. mm. an. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mm

5m o.“ n; ma. ma. mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12R

9m mw. fi; “w. om. CH aw. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mm

and n. fi; 3.. fin. mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iwh

mTN no. o...“ w». mm. ow. mo. mTN . . . . . . . . . . . . . .  . . . . . . . . . . . . . . . . . . . . . . Ion
dcfiohwu Mo
3.50m mm 15E Hmmzwbwtm cwfifiwznvO A Q5050
$33 53m
E33 om». 5E zsEcwmxm N732
$323 8.5m?“ <hwwwwmw> @5850 £128 QSNR N133 fiiQmfi
33w
QQuNOQ wmm~o>< mi mQ o
imoquczm Qswwz mvzaimw 33A woEEmm mfimfim

5 30>: we 2-353 0:305“. us: < EEu:>.c.£uonm UGG n32- flfllohz. i» uEuaE v.53 mo 2-356 0:333 0.5m

53w :5 mEauucuum-u

6 Q33.

19

SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS

o.~ m o.w_ mw._ Hm. v_._ . . 4 4 . . . . . . . . ‘ . . . , . . . 4 . 4 . . . . . ‘ . . . . . . . . . . . . . . . 4 . . . 4 . . . . . . . . . 4 . .4ww
n. n m.m mm.~ hm. mm. . . . . . . , . , . . . . . . . . . . . . . . . 4 . . . . . ‘ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..nw
n ~ v.mm wm._ om. ow. . . . . . . ‘ . . . . 4 . . . . . 4 . . ‘ . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..oh
.o=w~opwu Mo wopzow

mm 322i AUNESmV Essmhow 325m é nzobU

$0.? 6x.   xi.  . . . . . . . . . . . . . . . . . . . . . . . v . . . . . . . . . . . . . . . . . . . . . . - . . 

m.m m.m w.m mo." we mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . ‘ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._h

o.N N." v.N mm. ow mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..mn

w.~ H._ mmm oo._, mm mm. . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..wn

m.~ w. w.m o_._ ww . mm. . . . . . . . . . . . . . . . . . . . . . . . ‘ . ‘ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..wm

m. n. m.v_ wm._ Hm um. . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...m

w. w. m.w~ om.“ on mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..w

w. m. m.~m wv.~ hv. v_. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 _ . . . . . . . . . . . . . . . . . . . . . . ..hn

m. w. a.m mo._ hm mm. . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..wn

n. v. m.> mm. mm mo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..mh

m. n. N.n no.~ No vw. . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..n<
.@:u~o~wo we wohzom

mm umwzw Q@mm@;v_::zm~o».:w~U .N Q=¢uC
wx mo. ww.@ m¢._ @m. xa. . . . . . . . . . . . . . . 4 . . . . . . . . . . . ‘ . . . , . . . 4 . . . . . . . . . . . . . . ..¢umL@><

m.N m. c.m om._ mm mm. . . . . . . . . . . . . . . , . . . . . . , . . . . . . . ‘ . . . . . , . . . . . . ‘ . 4 . . . . . . . . . . . . . . . ..c_

m._ w. w.m_ wN._ mm mo. . . . . . . . . . . 4 . . . . . . . . . . . , . . . . . , . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,.ov

m._ w. a.m mN._ mm o~._ . . . . . . . . . . . . . . . . . . . . . . . . . ‘ . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..vm

o.~ o.~ m.@ ow._ an aw. . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..on

m. Q. w.¢ om.~ mm mo.~ . . . . . . . . . . . . . . . . 4 . . . 4 , . . . . . . ‘ . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~m

w. w. *o.o¢ *mw.h mm mm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . ..@m

¢. n. N.om mw.N mw._ @¢.H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..mm

n. w. w.m~ mw.~ oN.~ ¢H.~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..¢>

m. w. w.w mfi ~ hm. No.~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..m~

m. m. m.w~ wn N m~.~ we.“ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..wo

.@=v~o~mo we
uohsom mm 13E F2 wrmbw uvamuvzswfi A Qsotu

mi wfi m mi m1 q mi 1w mi m5 m mi mi w
wmsmimoz $3»
ncson ohm ngrs Qcucigoaxfl m¢*~¢@_

AE-i-N   N%&. IN.  ££-  4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

o.m m~.N ~.~ mm wfi. mm. . . . . . . . . . . . . . . . . . . , . 4 ‘ . . . . . . . . . . . , 4 , , . . . ‘ . . . . . . . . . . . . . . . . . , . .._n

c.n m_.~ m.~ ¢m. mm. fin. no wa _ , . . . , . . . . . . . . . 4 . . . 4 . . , . . . . . . . . . . . . . . . . . . ..mm

o.m m.m v.~ we wm mm. mm . . . , . . . . . . ‘ ‘ , . . . . . . . . . . . . , . , . . ‘ . . . . . _ . . . . . . . . . . . . . ..ww

o.n mm. o._ aw mm. mm. om . . . . . . . . . . 4 4 . , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 _ . . . ..vw

c.m uw._ n._ no vs. nu. oo. an _ . . . . . . . . ‘ . , . . . ‘ . . ‘ . . . . . . . . . . . . . . . . . . . . . . ..ox

dwEE/m E v3.32: 602*

   

.. _. W H W A
3..  S. w f: Ev Q; 2... . E. . . . . . . . . . . . . . . . . . . .  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..a::@><

4N m P». E i _ Ma;  W i. .
w  E w w m _ mm _ Z. _ 2..

. . . 1 . o. _ u... . m. ..
9». _ Q4.  <9 E xm; ma. . h... _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . z$
b; x. c.c_ oofi as. W _x. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I:
N; M... f: _ m»... S. W 2+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . i“.
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20 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

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SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 21

the four high ones averaged .81 ppm. Because of almost complete night
blindness there was no measurable difference in night blindness between
the steers so divided in respect to plasma and liver carotene.

In the second experiment the average carotene content of plasma
samples collected on April 15 were .98, .50, and .61 ppm. for the respective
groups. At the close, 41 days later, the respective values were .96, .58,
and .59 ppm., being practically unchanged for Groups 1 and 3 but
increased for Group 2. Within this period all groups increased in night
blindness. The carotene intakes during the period were near the average

Figure 4. Group 3 (1941-42) at close of 196-day feeding period after being fed an average
of 4.39 pounds of sweet sorghum (sumac) silage as source of carotene.

supplied during the entire test. The carotene content of livers, Steer 29 in
Lot 1 not included, were 1.62, 1.12, and 1.42 ppm. for the respective
groups. There was less variation in carotene content of livers in Groups
2 and 3 than in Group 1. On the average, the steers within groups which
showed the least night blindness had higher content of plasma and liver

carotene than those showing the most night blindness. This trend was.

most evident in Group 1. There was wide variation in spectro-vitamin
A content of livers in all groups.

22 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

Night blindness and the values found for plasma and liver carotene
are in agreement that Group 1, receiving alfalfa, was better supplied with
carotene than Groups 2 and 3. There was less night blindness in Group 2,
fed hegari silage as the source of carotene but livers and plasma showed
slightly lower content of carotene than Group 3 receiving sweet sorghum
silage.

The yearling steers showed much less night blindness and had larger
amounts of carotene in blood plasma and livers than the calves used
in the first experiment. This result was expected, although the intakes
of carotene were approximately the same for Group 1 in both experiments
and only slightly higher for Group 3 in the second experiment than
in the first; because the yearlings were on the test intakes only 147
days as compared to 196 days for the calves and in addition should have
had larger reserves of vitamin A potency at the outset than the calves.

It has been reported (2) (10) that .20 to .25 ppm. plasma carotene
is a critical level at which marked symptoms of vitamin A deficiency
may occur. This was strongly confirmed in the first experiment with

Figure 5. Steer 98, Group 2 (1941-42), fed grain sorghum (kafir and milo silage) as_source
of carotene, at close of 196-day feeding period. Note rough coat and slugglshness

SOURCES OF CAROTENE IN BEEF CATTLE F-ATTENTNG RATIONS 23

calves ‘in which 10 head showing complete night blindness, averaged
.28 ppm. plasma carotene. The same 10 head, three out of Group 1 and
seven out of Group 3, averaged .60 ppm. liver carotene. The blood plasma
and liver carotene levels at which slight degree of night blindness may
persist seem to be much higher. For example in the second experiment with
yearlings, slight to moderate degree of night blindness was evident in
Group 1 which showed averages of .96 ppm. plasma carotene and 1.62
ppm. liver carotene.

Condition of Steers: In the first experiment, 1941-42, Groups 2 and 3
had the advantage over Group 1 in flesh at the close and Group 3 was
more attractive than Group 2. Group 3 is shown in Figure 4. All groups

Figure 6. Group 2 (1942-43), at close of 196-day feeding period. Note good appearance and
finish.

showed evidence of vitamin A deficiency being less than normally alert.
The deficiency condition was most evident for Group 2.

Four steers in this group had unsteady gait, most hair coats were
rough and lifeless and one steer was obrgerved for four convulsions. This
steer is shown in Figure 5.

With one exception the yearling steers used in the second experiment,
1942-48, fattened and did not show external evidence of vitamin A de-
ficiency. A representative group is shown in Figure 6. Steer v29 in Group

>24 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

1- showed poor condition and had a marked fullness in the shoulder
region, but was only slightly night blind and had a much higher content-
of both carotene and spectro-vitamin A "in liver than any other steer.
This steer is shown in Figure 7.

Figure 7. Steer 29, Group 1, (1942-43) at close of 196-day feeding period. Note poor ap-
pearance and fullness in shoulder region. This steer showed 7.83 and 40.0 ppm.
carotene and spectro-vitamin A content of liver while the average of his 9 fellows
in Group 1 was 1.62 and 9.48 ppm. respectively.

Marketing and Slaughter: The steers were trucked from the Spur
Station to the Fort Worth market, a distance of 250 miles, both years.
rkrrivingat market some 36 hours before slaughter they were allowed water
and prairie hay. ‘

The calves sold at an average price of $12.38 per cwt. on June 22, 1942;
and the yearlings, except for one head, sold at market top, $16 per cwt.
on May 31, 1943. In both years all steers passed Federal meat inspection
requirements. A few of the yearling steers were noted for small amounts
of calculi in the bladders.

Carcass grades favored Group 2 each year and Group 3 had slight
advantage over Group 1. External fat covering the carcasses was notably
white for all steers.

“Asummary of the principal results of the two experiments is shown
in Table 6.

25

SOURCES OF CAROTENE IN BEEF. CATTLE FATTENING RATIONS»

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26 BULLETIN NO. 659, TEXAS AGRICULTURAL EXPERIMENT STATION

ACKNOWLEDGMENT

Dr. H. Schmidt, Chief, Division of Veterinary Science, T.A.E.S.; W. H.
Black, Senior Animal Husbandman, Beef Cattle Investigations, Bureau of
Animal Industry, U.S.D.A.; J. K. Riggs, Associate Professor of Animal
Husbandry, Substation No. 7, Spur, Texas, T.A.E.S., (on leave in U. S.
Navy) and P. T. Marion, Animal Husbandman, Substation No. 7, Spur,
Texas, T.A.E.S., (on leave in U. S. Army) assisted in planning and con-
ducting the work reported here.

SUMMARY .

Dehydrated alfalfa leaf meal, grain sorghum silage, and sweet sorghum
silage were compared as sources of carotene in rations for fattening
steers in two dry lot feeding trials. Steer calves of 330 pounds initial
weight were on test for 196 days in the first experiment, while yearling
steers of 570 pounds initial weight, although fed for 196 days in the
second experiment received the compared sources of carotene only during
the last 147 days.

There was much variation in pure carotene content of samples of the
sorghum silages taken at diflerent times. There was much less variation
in the pure carotene content of samples of dehydrated alfalfa leaf meal.
The carotene content of the silages declined in general from start to
close of the first experiment, 1941-42, but did not show this general
decline in the second experiment, 1942-43.

Sweet sorghum silage contained more carotene per pound in natural
state, although higher in moisture than grain sorghum silage. In the
first experiment, one pound of sweet sorghum silage contained on the
average as much carotene as 1.9 pounds of grain sorghum silage, but
toward the close of the feeding period the relation became one pound to
4.5 pounds. At this time calves could not consume enough grain sorghum
silage to receive an intake of 2000 micrograms of carotene.

A carotene intake approximating 2000 micrograms daily per 100 pounds
live weight did not prevent night blindness in either experiment. Ad-
vanced symptoms of vitamin A deficiency were observed for the light feeder
calves on test for 196 days in the first experiment. The yearling steers
used in the second experiment were less seriously affected although showing
partial night blindness during the latter part of the test period of 147 days.

In both experiments, Group 1, fed dehydrated alfalfa leaf meal as the
source of carotene, was less affected by vitamin A deficiency at the close
and showed more carotene in blood plasma and liver than the groups re-
ceiving silage. This indicates under the procedure followed that carotene
in alfalfa was more available than carotene in sorghum silages.

In the first experiment Group 2, fed grain sorghum silage as the source
of carotene, was more seriously affected by vitamin A deficiency than
Group 3, receiving sweet sorghum silage, but received only 59 per cent

 

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SOURCES OF CAROTENE IN BEEF CATTLE FATTENING RATIONS 27
as much carotene. In the second experiment this group received approx-
imately 12 per cent more carotene and while showing less night blindness
than Group 3 showed lower values for plasma and liver carotene. The
data do not warrant any distinction between the two silages in regard
to the availability of contained carotene. The general results in gain,
finish and marketability of steers show that either kind of silage may
supply sufiicient carotene in fattening rations to prevent injury from
vitamin A deficiency.

As judged by night blindness and other external evidence of vitamin A
deficiency within the respective groups, blood plasma and liver carotene
content appear to be about equally reliable and more reliable than
spectro-vitamin A content of liver as indicators of degree of vitamin
A deficiency. As between groups the values seemed to be less reliable
as indicators for both experiments, Group 1 steers, receiving alfalfa,
had a higher content of both liver and plasma carotene than similarly
night blind steers in the silage groups.

The plasma carotene level at which night blindness may occur was
not clearly defined, but it appears that a slight degree of night blindness
may persist in groups averaging 1.0 ppm. plasma carotene. Marked
symptoms of vitamin A deficiency occurred in the first experiment when
the carotene content of blood plasma averaged 0.28 ppm.

The carotene values found indicate that under practical Texas conditions
one pound of good quality sweet sorghum silage daily per cwt. may
prevent ill effects from vitamin A deficiency in fattening periods for
steers of about 200 days. From 2 to 3 pounds of good quality grain sorghum
silage may be necessary to secure the same result. Such amounts are not
expected to prevent varying degrees of vitamin A depletion, but when
added to the body reserves of vitamin A potency with which steers
usually enter the dry lot, should afford ample protection.

LITERATURE CITED

1. Jones, J. M., Keating, F. E., Jones, J. H., Black, WV. H., and Howe, P. E., Full and
limited feeding of fattening steer calves. Texas Agricultural Experiment Station
Progress Reports 628 and 629, (1939).

2. Jones, J. H., Schmidt, H., Dickson, R. E., Fraps, G. S., Jones, J. M., Riggs, J. K.,
Kemmerer, A. R., Howe, P. E., Black, W. H., Ellis, N. R., and Marion, P. T.,
Vitamin A studies in fattening feeder calves and yearlings, Texas Agricultura
Experiment Station Bulletin 630, (1943).

3. Ward, R. E., Bechdel, S. I., and Guerrant, N. B., Carotene and Vitamin A in the
nutrition of growing dairy cattle, Journal of Dairy Science, Volume 23: 115-124,
(1940).

Kemmerer, A. R., and Fraps, G. S., Constituents of carotene extracts of plants, Ind.
Eng. Chem. Anal. Ed., 15, 714-716, (1943).

Kemmerer, A. R., and Fraps, G. S., Nature of carotenes in alfalfa,
Chem. Soc., Volume 66: 305, (1944).

. Kemmerer, A. R., Fudge, J. F., and Fraps, G. S., Constituents of the crude carotene

of some forages, Journ. Amer. Soc. Agron., (In press 1944).

. Asso(cl. Oflicial Agr. Chem., Ofiicial and tentative methods of analyses, 5th ed., p. 369,
940

J ourn. Amer.

. Fraps, G. S., and Kemmerer, A. R., Improved method for estimation of carotene in

feeds, Journ. Assoc. Ofl’. Agr. Chem., Volume 22: 190-194, (1939).

. Fraps, G. S., and Kemmerer, A. R., The relation of the spectro-vitamin A and carotene
content of butter to its vitamin A potency measured by biological methods, Texas
Agricultural Experiment Station Bulletin 560, (1938).

. Davis, R. E., and Madsen, L. L., Carotene and vitamin A in cattlel blood plasma and

observations on reproductive performance at restricted levels of carotene intake,

Journ. of Nutrition, Volume 2: 135-146, (1941).

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