Department of Animal Science Florida Agricultural
Mimeograph Series No. 63-11 Experiment Station
October, 1962 Gainesville, Florida
PRELIMINARY OBSERVATIONS ON EFFECT OF
TEMPERATURE ON VITAMIN A STATUS IN CROSSBRED LAMBS
T. N. Meacham, T. J. Cunha, A. C. Warnick, P. E. Loqgins and R. L. Shirley l/
Recent reports have indicated an increased need for vitamin A by
cattle on feed during the warmer periods of the year (Beeson, 1962). It
is possible that the elevated temperatures encountered may have an adverse
effect on the utilization of vitamin A or that they may cause cattle to
have an increased physiological requirement for vitamin A.
The objectives of this experiment were to determine the effect of
two temperatures, 900 and 550 F,, on blood and liver vitamin A content,
feeding performance and growth rate of lambs fed adequate and low vita-
min A rations. The effect of temperature and low vitamin A on the re-
productive organs of the ewe lambs was also studied.
Twenty-four crossbred lambs were allotted to four treatment groups
of six lambs each on the basis of sex and previous treatment, Six of
the lambs had been in drylot since birth on a marginal vitamin A intake.
These lambs were distributed across all treatments. The remaining 18
lambs had been raised on pasture. The four groups were randomly assigned
to the following treatments:
Group Temperature Ration fed
I 900 F. Low vitamin A
II 90 F. Supplemented with vitamin A
III 550 F. Low vitamin A
IV 550 F, Supplemented with vitamin A
The lambs were maintained in two temperature controlled chambers;
one chamber was held at 550 and the other at 900 F. The lambs were
individually fed ad libitum in metal metabolism racks for the first 11
weeks and then were moved to individual feeding stalls on the floor of
the chambers for the remaining six weeks of the experiment. During
this six-weeks period, the lambs were confined in stalls at 7:00 A.M.,
fed and kept there until 5:00 P.M. when they were released and had access
to the open area of the chambers. Water was available to the lambs at
all times. The animals were weighed every seven days in the morning
i/ Meacham, now at Department of Animal Husbandry, Virginia Polytechnic
S Institute, Blacksburg, Virginia; Cunha, Animal Nutritionist and Head,
Warnick, Associate Physiologist; Loggins, Assistant Animal Husbandman
and Shirley, Animal Nutritionist.
The blood vitamin A levels were determined at three-week intervals
throughout the experiment. Liver vitamin A content was determined from
liver samples taken at the time of sacrifice. Standard analytical pro-
cedures were used in these determinations.
The low vitamin A ration (150 IU of vitamin A activity/lb.) fed
is shown in table 1. The supplemented groups received the same ra-
tion with 2,000 IU of preformed vitamin A added per pound of feed.
The reproductive tracts were taken from the ewe lambs at the time
of sacrifice. Weights of the ovaries, uteri, pituitary glands, number
of corpora lutea and size of follicles were obtained.
Table 1. Ration Fed Lambs on Vitamin A Temperature Study
White corn 59.0
Cob and shuck meal 21.0
Cottonseed meal 15.4
Molasses, cane 3.0
Salt, trace mineralized 0.6
Vitamin mix I
1/ Vitamin mix:
A 2,000 IU/lb. of feed in the supplemented ration only.
D 500 IU/lb. of feed in all rations.
E 10 mg. (IU)/lb. of feed in all rations.
Results and Discussion
Four lambs, two from each of the low vitamin A groups, died or were
sacrificed before the end of the experiment. Three of the lambs had
been raised in drylot since birth and probably had very low vitamin A
storage at the time the experiment started. The two lambs from the 900 F.
chamber were removed 42 and 64 days after the experiment started. The
one lamb in the 550 F. chamber was removed after 52 days. These lambs
displayed the characteristic loss of coordination and inability to stand
associated with a vitamin A deficiency (Lindley et al. 1949). Blood
and liver analyses for vitamin A verified the external symptoms of the
vitamin A deficiency. The average blood vitamin A contents were 1.6 and
1.0 mcg./100 ml. of plasma for the two lambs in the heated chamber and
the one lamb in the cold chamber, respectively. Average liver vitamin A
contents were 0.69 and 0.30 mcg./gram of fresh liver for the two lambs in the
heated and the one lamb in cold chamber, respectively. The other lamb in
the cold chamber that died was a pasture lamb and the cause of death was
not attributed to a vitamin A deficiency as the blood vitamin A level was
14.6 mcg./l0 ml. of plasma just prior to death. This lamb died 45 days
after the start of the experiment.
Blood and liver vitamin A levels, feed intake, feed efficiency
and average daily gain (ADG) values for the four treatment groups are
given in table 2.
Table 2. Effect of Temperature and Vitamin A Levels
on Blood and Liver Vitamin A, Growth and Feeding Performance
90T F. 550 F.
Plus Low Plus Low
Vitamin A Vitamin A Vitamin A Vitamin A
No. of animals 6 6 6 6
Blood vitamin A,
mcg./100 ml. plasma
Initial 35.52 31.21 35.85 31.45
Final 28,52 26.60a 40.45 32.70a
Av, per temperature group 27.56** 36.57
Liver vitamin A,
mcg./g. fresh liver 11.82 20.25a 14.75 10.97a
Feed intake, lbs./day 1.83 1.61b 2.04 2.50b
Av./temperature group 1.72* 2.27
Feed/lb. of gain, lbs. 14.76 22.05 10.25 12.50
Av. daily gain, lbs. 0.124 0.073 0.199 0.200
P<0- r^7o5- -I ---- -
a M-in of the four lar~. s su:zviving in each low vitamin A group.
b HWighted means including the four lambs which did not complete the
Statistical analysis of the data indicates that the vitamin A con-
tent of the blood of the lambs in the heated chamber was significantly
lower (P< .05) than that in the lambs in the cold chamber. These values
were 27.56 and 36.57 mcg./100 ml. plasma, respectively. There was, however,
no significant difference between the two dietary levels of vitamin
A on blood vitamin A levels. The vitamin A supplemented groups tended
to be higher at both temperatures. This is in agreement with the
work reported with cattle in which the elevated temperatures lowered
blood vitamin A levels (Beeson, 1962). The fairly high level of vitamin
A maintained in the blood of the lambs on the low vitamin A rations was
probably due to ample liver storage of vitamin A.
Analysis of the livers for vitamin A content at the end of the ex-
periment revealed widely varying concentrations in all treatment groups
as shown in table 2. The liver storage at the start of the experiment
is not known; therefore, the changes which may have taken place due to
the treatments cannot be evaluated. It is obvious, however, that the
experimental period of 118 days was not long enough to deplete the livers
of vitamin A. Lindley et al. (1949) report that as long as 250 days
may be necessary to comp-Te-ely deplete sheep of vitamin A.
The 900 F. temperature significantly decreased the feed intake
(P<.05) as compared to the intake at the 550 F. Again, the supple-
mental vitamin A did not significantly increase feed intake. There
was, however, an interaction (P<.05) between temperature and vitamin
A supplementation. The low vitamin A group in the cold chamber con-
sumed more feed per day than the supplemented group, while the reverse
was true at the high temperature (table 2). The reason for this re-
There were no significant differences in the ADG between any of
the treatments, although the gains tended to be higher in the cold
chamber. This is to be expected since the feed intake was greater in
these groups also. The lambs receiving the vitamin A supplementation
gained slightly more than those on the low vitamin A rations. The
considerable variation in performance within treatment groups accounted
for the failure to obtain statistical significance.
The feed efficiency values were not analyzed statistically due to
the negative gains made by some of the lambs. The efficiency did,
however, tend to be greater at the cold temperature and also greater
for the vitamin A supplemented groups.
No gross abnormalities were observed in any of the lambs at the
end of the experiment.
The average weight and sizes of the reproductive organs of the
eight ewe lambs sacrificed are given in table 3. Neither the tempera-
ture nor the level of vitamin A appeared to influence growth or activ-
ity of the ovaries, uteri or pituitary glands (table 3.)
Table 3. Effect of Temperature and Vitamin A on Reproductive Tissues
No. No. Size Weight
Ewe Ovary Uterus Recent Old Largest of
Group No. Weight Weight C.L.a C.L. Follicle Pituitary
(gms.) (gms.) (Mm.) (gms.)
Cold 550 F.
Control 7 1.0 27.5 1 2b 5 0.4
25 1.4 18.1 1 0 5 0.3
10 1.5 28.2 2 1 3 0.6
Av. I 2 T T1 43 0.4
Low Vit. A 21 2.1 30.9 2 0 8.0 0.3
24 2.0 30.8 2 0 7.0 0.2
Av. T0T 08 7 T1 72
Heat 900 F.
Control 18 1.6 21.3 1 0 5.0 0,8
1 1.9 22.8 1 1 5.0 0.7
Av. 1.7 22,0 1 0.5 5.0 0.7
Low Vit. A 19 2.4 21.5 1 1 6.0 0.6
a C.L. = Corpora lutea.
b Represents two different ovulations or previous estrus cycles.
Twenty-four crossbred lambs were used to study the effect of two
environmental temperatures, 900 and 550 F., and two levels of vitamin
A intake on the growth, feeding performance and vitamin A levels in
the blood and liver.
The high temperature lowered feed intake (P<.05) and blood vita-
min A (P<.01). Supplemental vitamin A tended to increase feed intake,
gains and blood vitamin A levels, but the increases were not statisti-
cally significant. The three lambs which had been on a marginal vita-
min A intake prior to the start of the experiment died or were sacri-
ficed after 53 days on the low vitamin A ration.
Due to the short experimental period, liver vitamin A stores were
not sufficiently depleted to show any treatment effect.
The two temperatures and vitamin A levels had no apparent effect
on the development and activity of the reproductive glands of the ewe
lambs used in the experiment.
1. Beeson, W. M. 1962. Personal Communication.
2. Lindley, C. E., H. H. Brugman, T. J. Cunha and E. J. Warwick.
1949. J. Animal Sci. 8:590.