Report on the Agricultural Experiment Stations, 1954 Page: 59
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inbred lines. In feed-lot performance tests, linecross bulls gained faster and were
superior in live grade at yearling age compared with inbred bulls.
At the Ohio station (coop. USDA), bulls from inbred lines developed by the Department
in cooperation with the Montana and Nebrasks stations are being evaluated in comparison
with non-inbred purebred bulls for improving production in commercial beef herds.
First-year results show that the progeny of Montana line 1 bulls averaged 12 pounds
heavier at weaning than those of outbred bulls, when mated with similar grade Hereford
heifers. In a feeding trial, steer calves sired by the inbred bulls gained 2.42 pounds daily
compared with 2.02 pounds for the progeny of outbred bulls, and consumed less feed per
100 pounds of gain with a saving of about 13 percent in total feed cost. Heifer progeny of
the inbred bulls showed an advantage of 8 percent in daily gain, and 14 percent in feed
efficiency. Progeny of the Nebraska line 1 bulls were superior to those of outbred bulls
in daily gains, with a small advantage in feed efficiency.
Culling low-producing cows
Low-producing cows can be culled from the herd with reasonable accuracy on the
basis of one or two calf crops, studies conducted by the Tennessee station (coop. USDA)
showed, confirming last year's report by the Oklahoma station. The tendency for cows
is to wean calves of similar weight and type in successive years. By adjusting weaning
weights of the calves for the effects of important environmental factors, the accuracy
of selecting breeding stock each year can be improved. In the Tennessee experiments
cows reached maximum productivity at the age of 7 to 8 years. Differences in weaning
weights of calves between 2- and 8-year-old cows were as much as 80 pounds.
Summer gains indicative of heat tolerance
The Texas station (coop. USDA) has been conducting heat-tolerance studies with
beef cattle in an effort to find criteria that may be useful in the selection of breeding
animals adapted to climatic conditions of the southern region. Although Brahman cattle
had significantly lower rectal temperature, respiration rate, and pulse rate than Herefords
under both field and controlled conditions, summer gains on pasture were similar for the
two breeds. Crossbred progeny were intermediate between the parent breeds in rectal
temperature and respiration rate, but they had a higher pulse rate and made greater
summer gains. Estimates of the heritability of summer gains indicate that selection
for this trait should be effective.
Breeding 2-year heifers
Breeding heifers to calve first at 2 years of age instead of the usual 3 years resulted
in about one extra calf per cow at 5 years of age, with no additional feed cost, according
to the Oklahoma station. Different levels of supplemental winter feeding or age at first
calving had little effect on mature body weights of the cows or weaning weights of their
calves, when the cows had access to an abundance of summer and winter pasture. A
combination of early calving and low nutrition retarded somewhat the development of the
cows, but those which calved first at 2 years averaged only 51 pounds lighter at5-1/2
years than cows calving first at 3 years. Total feed and pasture costs for cows wintered
at a high level were 80 percent greater, and those wintered at a medium level were 35
percent greater than costs for cows wintered at the low level.
Beef Animal Rations
Iowa stilbestrol trials
Yearling steers fed a small amount of stilbestrol daily with a fattening ration yielded
an extra 0.83 pound of gainper dayin a 112-day feeding test conducted by the Iowa station.
Steers receiving the hormone gained 3.06 pounds daily compared with 2.23 pounds for the
control lot fed the same rationwithoutthehormone, and they made this gain on 20 percent
less feed per pound of gain. The two lots of steers were comparable in carcass quality,
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1954, book, April 1955; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5988/m1/63/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.