ANIMAL HUSBANDRY RESEARCH 39
of improving productive efficiency and carcass quality of beef cattle
under different environmental conditions.
The weaning weight of the calf is an important factor in evaluating
cow performance. The Oklahoma station (coop. USDA) found that
selection for weaning weight could be made more effective by correcting
for the effects of certain environmental factors. The age and sex
of the calf, the age of its dam, and the year in which the calf was
raised were important factors governing weaning weight. Cows
tended to repeat their performance, which indicates that females can
be culled for mothering ability on the basis of their first calf record.
The New Mexico station (coop. USDA) demonstrated that calf
grade at weaning age is not associated with subsequent gain in the
feed lot or carcass grade. Yearling feeder grade had a low but significant
influence on carcass grade. On the other hand, the gains made
by cattle on feed were found to be closely related to the live grades
and carcass grades of fat cattle. The results of the New Mexico study
give additional proof that selection of cattle for gaining ability can
benefit both the breeder and feeder.
The Montana station (coop. USDA) learned that heifer progeny
groups wintered on a good growing ration ranked in the same order
for rate of gain as full-fed steer progeny sired by the same bulls.
Results of a 7-year comparison of feed-lot gains with gains on good
range indicate that the sire progeny that made highest gains on
pasture also gained more in the feed lot. This supports earlier results
at the New Mexico station.
Through the use of performance-tested bulls, the Oregon station
(coop. USDA) has been able to bring about considerable improvement
in the rate and economy of gain in each of their Angus and Hereford
lines within a single generation of cattle, even though some inbreeding
was practiced. The improvement in rate of gain, ranging up to as
much as 30 percent for some bulls, was greater than the improvement
in feed efficiency. In performance testing, bull calves are generally
fed for a period of about 180 days. The station found that records
on feed efficiency of calves can be evaluated more critically when the
animals are fed to make a given amount of gain. For calves fed on
this basis there was a significant correlation between time and feed
required to make the gain, whereas there was no correlation between
gains and feed consumed when calves were fed on a time constant basis.
The Utah station (coop. USDA), found that efficiency of gain is
influenced significantly by weight of the calves at the beginning of
the feeding period as well as by sire and sex. With increase in size,
calves tend to gain faster but less efficiently.
At the Colorado station (coop. USDA) crosses of inbred Hereford
lines resulted in calves that were 12 percent heavier at weaning and
11 percent higher in grade than inbred calves sired by the same bulls
and out of inbred cows. Bulls produced from the crossline matings
were also heavier and graded higher at yearling age than inbred
bulls. In cooperators' herds, inbred sires produced calves that averaged
19 pounds heavier at weaning than the progeny of selected
outbred bulls. If substantiated by later results, these methods should
prove valuable as a means of increasing productivity of beef herds.
United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1953. Washington D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc5989/. Accessed October 9, 2015.