TECHNICAL BULLETIN 667
The Effect of Winter Gains of
Beef Calves on Subsequent
F. M. PEACOCK
W. G. KIRK
E. M. HODGES
A. Z. PALMER
J. W. CARPENTER
AGRICULTURAL EXPERIMENT STATIONS
UNIVERSITY OF FLORIDA, GAINESVILLE
J. R. BECKENBACH, DIRECTOR
REVIEW OF LITERATURE ............................ ................. ........... 3
EXPERIMENTAL PROCEDURE .......... ................................ 4
EXPERIMENTAL RESULTS AND DISCUSSION .......................................................... 9
W inter Performance .................... .............. .......................... ..... ............ 9
Feedlot Performance ................................ ... 9
W inter Plus Feedlot Performance ....................................................... 10
SUMMARY AND CONCLUSIONS ................................................................................... 11
LITERATURE CITED .......................................... ............ 12
THE EFFECT OF WINTER GAINS OF
BEEF CALVES ON SUBSEQUENT
F. M. PEACOCK, W. G. KIRK, E. M. HODGES, A. Z. PALMER,
and J. W. CARPENTER 1
Beef cattle production is affected by many nutritional and
environmental influences, with availability of quality winter feed
a major factor. This is particularly true under range condi-
tions where animals depend on pasture for feed. There is usually
a plentiful supply of feed during spring and summer, but fre-
quently both quality and quantity of forage are reduced as the
growing season progresses. Grass is often inadequate to main-
tain the herd during the winter period, and the cattle need sup-
plemental feed to prevent excessive loss of weight.
Mature cattle are more adapted to winter feed conditions
than calves due to a larger capacity for the utilization of low-
quality forage. Their relatively high nutrient requirement and
limited feed capacity place calves in an unfavorable position
when the whole ration consists only of mature, weather-damaged
forage and mineral supplement.
Feeding trials were planned to determine the effect of dif-
ferent rates of calf gains after weaning on (a) efficacy of nutri-
ents for gains during the winter; (b) subsequent feedlot per-
formance; (c) overall feed efficiency, including both winter and
dry lot periods.
REVIEW OF LITERATURE
Pfander (4)2 wintered steers at average daily gains of 0.04
pound and 1.5 pounds, followed by 103 days on pasture, and
then finished them in the feed lot to a U. S. Choice slaughter
grade. Steers wintered at the lower level of gain required more
time to reach a certain slaughter grade (on-foot) than steers
wintered on the higher levels of nutrition; steers wintered at the
low level of gain had fatter carcasses, but the carcass grade was
lower due to less marbling.
1The authors are (in order named) Associate Animal Husbandman, Vice-
Director in Charge, and Agronomist, Range Cattle Station, Ona; Associate
Meat Scientist and Assistant Meat Scientist, Animal Science Department,
Main Station, Gainesville.
2 Number in parentheses refer to Literature Cited.
Florida Agricultural Experiment Stations
Research on interrupted growth of calves has been carried
out by Winchester and Howe (7) with identical twin calves.
They concluded that beef cattle six to eight months of age
could be carried safely at a maintenance energy level for six
months, if nutritional needs other than those for energy were
supplied. No subsequent loss in efficiency of feed utilization,
meat quality, or the proportion of lean meat in the carcass re-
sulted. However, in most instances animals on the restricted
energy diet required 10 to 20 weeks longer on full feed to obtain
the same slaughter weight and carcass grade as the liberally
fed cattle. This is in agreement with a later study by Win-
chester and Ellis (6) in which growth of calves between three
and six months and four to eight months of age was held to a
Story and Hazel (5) found that calves gaining an average
of 1.37 pounds daily while being wintered on roughage had
higher daily gains and required less feed for gain during the
subsequent fattening period than calves averaging 1.95 pounds
daily. The low winter gaining calves required a longer time to
reach market weight than animals gaining at the higher level.
Carcass grade was higher for the faster gaining winter group.
A preliminary study was made by Gilbreath (2) to determine
the effect of four levels of nutrition of weanling calves during
a 119-day winter pasture feeding period on subsequent feedlot
performance and carcass characteristics. The average daily
winter gains by lots were 0.06, 0.45, 0.82, and 1.11 pounds, while
feedlot gains were 2.08, 2.29, 1.85, and 1.96 pounds per day,
respectively. Lots 1 and 2 had a U. S. Low Good carcass grade
and Lots 3 and 4, U. S. High Good. Animals in Lot 1 dressed
58.14 percent and those in Lots 2, 3, and 4 dressed 60.32, 60.32,
and 61.49 percent, respectively.
The study reported here involved three years' data in which
144 heifer calves were used in three trials of 48 animals each
to determine the effect of rate of gain during winter on subse-
quent feedlot performance. The 48 calves in each trial, divided
into four groups of 12 animals each, were wintered on low-
quality pasture, and given supplemental feed to produce daily
gains as follows by lots: (a) maintain (no gain) weight; (b)
Winter Gains of Beef Calves
gain 1/4 to 1/2 pound; (c) gain 2/3 to 3/4 pound; and (d) full-fed
for maximum gain.
The calves were approximately 71/2 months of age at the
beginning of each trial with an average weight of 375 pounds.
Breeding of animals was predominantly grade Brahman with a
few grade Shorthorns included. The four groups of calves, sim-
ilar in breeding, weight, and feeder grade, were each placed on
5-acre Bahiagrass pastures in October for the 120-day winter-
ing phase of the trial. Each group was fed during this period
a ration of cottonseed meal and citrus pulp, the amounts being
adjusted periodically to control rate of gain. Weights were
recorded every 28 days. At the end of this phase the four
lots of animals were weighed and graded individually, placed
in drylot, and full-fed for 140 days. The average daily sup-
plemental rations fed to each group of 36 animals during the
winter phase are given in Table 1.
TABLE 1.-AVERAGE DAILY RATION OF CALVES BY WINTER GAIN GROUPS.
Feed 1 2 3 4
Bahiagrass pasture ad lib ad lib ad lib ad lib
Cottonseed meal, 41% protein, lb. 1.06 1.28 1.57 1.73
Citrus pulp, lb. 0.89 1.74 3.96 6.45
Mineral, lb. 0.02 0.02 0.02 0.03
Total, lb. 1.97 3.04 5.55 8.21
t Mineral mixture composed of 28 parts steamed bonemeal, 28 parts defluorinated phos-
phate, 31.21 parts common salt, 3.12 parts red oxide of iron, 0.63 parts copper sulfate, 0.04
par:s cobalt chloride or sulfate, 7.00 parts cane molasses, and 2.00 parts cottonseed meal.
Drylot feeding began in February and ended in late June
or early July each year. Pens were neither paved nor covered,
and the cattle were exposed to rainfall and temperature extremes
on several occasions. Animals were fed once daily a ration
consisting of pangolagrass hay and a mixture composed of the
following, on a percentage basis: cottonseed hulls, 20; cotton-
seed meal (41 percent protein), 19; citrus pulp, 41; corn meal,
14; alfalfa, 5; and complete mineral, 1. The average daily ra-
Florida Agricultural Experiment Stations
tion during the feedlot period for each group is given in Table 2.
A complete mineral mixture was available at all times in addi-
tion to that mixed in the feed. At the completion of the feedlot
period each year, all animals were weighed, graded, and hauled
a distance of 197 miles to the University of Florida Meats Lab-
oratory, Gainesville, Florida, for slaughter.
TABLE 2.-AVERAGE DAILY RATION DURING FEEDLOT PERIOD.
Feed 1 2 3 4
Pangolagrass hay, lb. 2.14 2.16 2.14 2.07
Cottonseed hulls, lb. 3.44 3.65 3.75 3.62
Cottonseed meal (41% protein), lb. 3.37 3.48 3.56 3.48
Citrus pulp, lb. 7.33 7.44 7.62 7.33
Corn meal, lb. 2.35 2.41 2.45 2.46
Alfalfa pellets (17% protein), lb. 0.89 0.91 0.93 0.91
Mineral,t lb. 0.23 0.28 0.27 0.27
Total, lb. 19.75 20.33 20.72 20.14
t Mineral mixture given in Table 1.
Measurements made during the three trials and included in
the analysis of the data were: (a) average winter daily gain;
(b) estimated winter slaughter grade; (c) feedlot average daily
gain; (d) carcass grade; (e) dressing percent; (f) TDN (total
digestible nutrients) per 100 pounds gain ([Morrison (3)]); (g)
total gain for winter plus feedlot; (h) TDN per 100 pounds
gain for winter plus feedlot (winter pasture not included). The
data were analyzed by analysis of variance, and tested for signi-
ficance by using Duncan's "New Multiple Range Test" (1).
The winter data were analyzed statistically to determine
whether the differences in performance were real rather than
by chance as a basis for evaluation of animals' feedlot perform-
TABLE 3.-EFFECT OF LEVEL OF WINTER SUPPLEMENTATION ON RATE OF GAIN,
DRESSING PERCENT, AND CARCASS GRADE.
SUBSEQUENT FEEDLOT PERFORMANCE,
Significance of Differencet
4 1&2 1&3 1&4 2&3 2&4 3&4
No. of anim als ......................--................. 36
Av. initial wt., lb. ...........-...............
Av. final wt., lb. .....................-........
Av. daily gain, lb.........................-- .....
Av. slaughter gradeft ..---........-........
Av. initial wt., lb. ...........................
Av. final wt., lb. .................................
Av. daily gain, lb. ........................
Av. carcass grade .............................
Av. dressing percent -......................
TDN per 100 pounds gain ....-..........
Winter + feedlot
Total gain, lb. ............................... 327
TDN per 100 lb. gain --.....--- ---........-- 577
**~ o ***88 ** **
*.* ** ** ** ** **
344 378 399 NS ** ** ** ** NS
585 595 613 NS NS NS NS NS NS
f NS Non-significant; difference significant at the .05 level of probability; ** difference significant at the .01 level of probability.
tt Grades: 3, Low Utility; 4, Utility; 5, High Utility; 6, Low Standard; 7, Standard; 8, High Standard; 9, Low Good; 10, Good.
$ Slaughter weight, Ona, and chilled carcass weight obtained after chilling 48 hours.
Morrison's Feeds and Feeding was used as a basis for calculating TDN values.
TABLE 4.-MEAN SQUARES OBTAINED IN ANALYSIS OF VARIANCE TREATMENT OF DATA.
Degrees of freedom
TDN per 100 pounds gain
Winter + Feedlot
TDN per 100 pounds gain
Source of Variability
Lots Y x L Residual (error)
* Significance at the .05 level of probability.
** Significance at the .01 level of probability.
Winter Gains of Beef Calves
EXPERIMENTAL RESULTS AND DISCUSSION
Adjusting the supplemental ration between groups during
the winter period resulted in highly significant differences for
average daily gains and slaughter grade. Average daily gains
ranged from 0.09 pound for the lowest supplemental group to
1.21 pounds for the animals receiving the most feed. These
variations in gain resulted in slaughter grades, ranging from
U.S. Utility for animals gaining 0.09 pound daily to Low Good
for those gaining 1.21 pounds. Means for average daily winter
gain and estimated slaughter grade along with levels of signifi-
cance are given in Table 3. Mean squares and significance levels
for daily gain and slaughter grade are given in Table 4.
Daily Gain.-Mean squares and significance levels for the
various measures of feedlot performance are given in Table 4.
Differences in average daily gains among winter groups in feed-
lot were significant at the .01 level of probability. Lot 1, gain-
ing 0.09 pound daily during winter, was the highest gaining
group in feedlot, while Lot 4, making 1.21 pounds daily, was the
lowest gaining group in feedlot. There was a negative relation-
ship between estimated winter slaughter grade and feedlot gains.
This was probably the result of animal utilization of nutrients,
as Morrison (3) has shown that less nutrients are required for
gains represented by growth than for gains resulting from the
deposition of fat. Daily gain means and test of significance among
means are given in Table 3.
Carcass Grade.-U. S. carcass grades were High Standard,
Low Good, Low Good, and Good for Lots 1, 2, 3, and 4, respec-
tively. There were highly significant differences between car-
cass grades for Lots 1 and 3 and 1 and 4, while the difference
between Lots 1 and 2 was significant at the .05 level of prob-
ability. There were no significant differences in carcass grades
among Lots 2, 3 and 4. The two primary factors influencing
carcass gradability were conformation and degree of marbling,
as animal age and carcass maturity were similar among lots.
The small increase in carcass grade, based on the beginning es-
timated slaughter grade, for animals in Lot 4 during the feedlot
period indicated a limitation in the ability of the animals in this
10 Florida Agricultural Experiment Stations
experiment to grade above U. S. Good. The small variations in
carcass grades were probably the result of this limitation. Lot
1 had the lowest carcass grade, which was probably due to lack
of time in drylot. Means and test of significance among means
for carcass grade are given in Table 3.
Dressing Percent.-Means for dressing percent and test of
significance among means are given in Table 3. There were
highly significant differences between Lots 1 and 3, 1 and 4, and
2 and 4. Differences between Lots 1 and 2 and 3 and 4 were sig-
nificant at the .05 level of probability. There was no significant
difference in dressing percent between Lots 2 and 3. There was
an increase in carcass yield as the animals improved in condition.
TDN per 100 Pounds Gain.-Efficiency of feed utilization for
gain was calculated on a lot basis because animals were group
fed. Cattle which gained least during winter utilized feed more
efficiently in the feedlot. Other lots decreased in efficiency as
prior winter gains increased, and differences among means were
highly significant. Means and levels of significance among means
are given in Table 3. These variations in amount of feed re-
quired for gain were considered to be a reflection of body utiliza-
tion of nutrients. As animals become more mature, gain is in-
creasingly the result of the deposition of fat, and growth plays
a secondary role in producing weight increase. More nutrients
are required for weight gain represented by fat deposition than
by growth; therefore, apparent efficiency of feed utilization is
dependent upon the stage of maturity and degree of fatness of
Winter Plus Feedlot Performance
Total Gain.-Mean squares and significant levels for winter
gain plus feedlot gain and TDN per 100 pounds gain are given
in Table 4. Combining winter gains and those made during the
feedlot period resulted in Lot 1 gaining an average of 327 pounds
per animal and Lots 2, 3, and 4 gaining 344, 398, and 399 pounds,
respectively. There were no significant differences between Lots
1 and 2 and 3 and 4. Highly significant differences were found
between Lots 1 and 3, 1 and 4, 2 and 3, and 2 and 4. Since winter
and feedlot gains were inversely related, there was a tendency
for the total gain between groups to balance for the two periods.
Means and levels of significance for winter plus feedlot gains are
found in Table 3.
Winter Gains of Beef Calves
TDN per 100 Pounds Gain.-There were no significant dif-
ferences among means when supplement TDN was combined for
both the winter and feedlot period. Efficiency of feed utilization
for the winter period and feedlot period were inversely related,
resulting in the variations to be minimized when the two periods
were combined. The average means are shown in Table 3.
SUMMARY AND CONCLUSIONS
The effect of winter supplemental feeding of calves on their
gains and subsequent feedlot performance was measured in
three trials, 1958-59, 1959-60, and 1960-61. Heifer calves with
an estimated Standard slaughter grade were wintered for 120
days on pasture at four levels of feeding, making average daily
gains of 0.09, 0.29, 0.77, and 1.21 for Lots 1, 2, 3, and 4, respec-
tively. These levels of gain resulted in a Low Utility slaughter
grade for the calves in Lot 1, gaining 0.09 pound daily, ranging
up to Low Good for Lot 4, gaining 1.21 pounds.
An average daily gain of 0.77 pound per day was required to
maintain the animals' slaughter grade for the four-month period.
The maintenance ration did not appear to affect skeletal growth
but resulted in an excessive loss of condition. There was a posi-
tive relationship between rate of gain and efficiency of feed utili-
zation during the winter period. An increase in gain resulted
in a higher percentage of feed used for gain and also improved
the condition of the animals above that of the maintenance level.
Daily gains during the 140-day feedlot period were inversely
related to the winter gains. The animals in Lot 1, making the
lowest gain during winter, made the highest gains in feedlot.
An increase in winter gains resulted in lower feedlot gains, with
Lot 4 gaining the highest during the winter and the lowest during
the feedlot period.
Dressing percent was positively related to winter gain, total
gain, and carcass grade, but inversely to feedlot gains.
Differences among means for efficiency of feed utilization for
gain during the feedlot trial were highly significant; efficiency
was highest for the maintenance winter group and reduced as
winter gains increased.
The total gains for the winter plus feedlot periods ranked the
same as for winter gain with highly significant differences among
all means except Lots 1 and 2, and 3 and 4.
Florida Agricultural Experiment Stations
Efficiency of feed utilization for gain for the entire trial, in-
cluding both the winter and feedlot periods, showed no significant
lot or treatment differences.
Weanling calves can be wintered at a maintenance level of
gain without adversely affecting their ability to gain weight
and improve in condition during the following growth period
with adequate nutrition. If the normal rate of gain for growing
animals is interrupted for a short period of time without affect-
ing skeletal growth, there is a tendency to equalize weight gains
later under optimal conditions.
Rate of gain and efficiency of feed utilization for gain are
dependent in part upon the maturity and degree of fatness of an
animal during the feeding period. Rate of gain and degree
of fatness of calves during thp winter have a significant influence
upon performance during the following feeding period.
1. Duncan, D. B. Multiple range and Multiple F. tests. Biometrics, Vol.
2. Gilbreath, R. L. The effect of supplementation during wintering of
calves on subsequent feedlot performance, slaughter and carcass char-
acteristics. M. Science Thesis, Univ. of Fla. 1959.
3. Morrison, F. B. Feeds and feeding. 22nd ed. Morrison Publ. Co. Ithaca,
N. Y. 1956.
4. Pfander, W. H. Effect of plane of nutrition on quality of beef. Mo.
Agr. Exp. Sta. Bul. 652. 1955.
5. Story, C. D., and A. J. Hazel. Wintering calves for summer fattening
in drylot. Col. Agr. Exp. Sta. General Series Paper 671. 1957.
6. Winchester, C. F., and N. R. Ellis. Delayed growth of beef cattle USDA
Tech. Bul. 1159. 1956.
7. Winchester; C. F., and P. E. Howe. Relative effects of continuous and
interrupted growth of beef steers. USDA Tech. Bul. 1108. 1955.