The LiveWiRED project is nearly two and a half years into action. Forty-two
calves have been weaned and are being backgrounded in Missouri with plans for
shipment to a Kansas feedlot in early August. With newly collected weaning
weight data, the project is one step closer to unveiling the power of EPDs for
the genetic improvement of the Red Angus breed as well as the beef industry as
a whole.
About the Project
The initial design of the LiveWiRED project was to evaluate the actual
performance of sires compared to what their EPDs predict. In order to obtain an
accurate assessment of the sires, a Gelbvieh cow named Penny was used as the
sole donor cow for the entirety of the project. By utilizing a single donor cow
as the dam of all the LiveWiRED calves, we can isolate sire-side genetics and
obtain results that accurately portray the performance of multiple Red Angus sires
compared to what their EPDs predicted.
Penny was flushed to five different bulls to produce calves for this
project. Three of these Red Angus bulls rank high in the breed for growth and
carcass traits and are referred to here as “high-growth sires.” The other two
bulls rank poorly in the breed for growth and carcass traits and are referred
to as “low-growth sires.” Throughout the duration of the project, the two sire
groups will be compared in various ways, and, in some cases, calves by
individual sires will also be compared to determine if observed performance differences
match those predicted by the sires’ EPDs.
Project Update—Weaning Weights
Taking a look at the entire calf crop, the heaviest weaned calf stepped on
the scale at 486 pounds while the lightest calf came in at 351 pounds. The
average weaning weight was only 421 pounds after the 205-day adjustment. With
weaning weights being significantly lighter than expected for all progeny, there
is little doubt that non-genetic factors caused reduced growth rates. Sub-par
nutrition took a toll on the calves and they were also affected by drought,
which has been a problem in the area where the calves were raised.
When evaluating bulls and heifer calves in the Red Angus breed overall, the
average weight difference among fall-born calves is 42 pounds, with bulls being
heavier. The LiveWiRED calves showed only a 19-pound difference in 205-day
weights between the sexes (less than half the normal weight difference).
Nutritional/environmental limitations undoubtedly created the lack of spread
between the heifers and bulls across all calves in the project, and also
limited the growth expression of the high-growth versus low-growth sired
calves. Weight differences between the bulls and heifers were ‘compressed’ by
environmental factors, so it is understandable that the sires’ Weaning Weight
EPDs were not fully expressed either.
For the purpose of this discussion and analysis, all calves were adjusted
to a 205-day weaning weight and all heifers were adjusted up 19 pounds to
account for observed sex differences. Sire EPDs are the main factor being
evaluated in the project, since all calves have the same dam. One sire in the
high-growth group, Sire A, sired 16 calves. Six of these calves ranked in the
top 10 for heaviest weaning weight among all project calves. The adjusted 205-day
weights for high-growth Sire A were then compared with the weights from
low-growth Sire B, who sired 11 calves in a simple statistical test. Sire A and Sire B were the top two sires in
progeny count, so it made sense to directly compare their progeny.
The data showed that high-growth sire A calves weighed, on average, 22.6
pounds more than low-growth sire B’s calves. The actual difference in Weaning
Weight EPD between these two sires is 40 pounds, so only a little over half of
this genetic difference was actually expressed due to the aforementioned
non-genetic limitations. Even so, our p-value was 0.04 (p<0.05) in this
analysis, therefore, we can be more than 95 percent confident that a
statistically significant difference in weaning weight occurred between the two
sire groups. The graph below provides a good visual of this data, illustrating the
cause-effect result between Weaning Weight EPDs and actual weaning weights.
The weaning weight data is giving us a great start in comparing Red Angus sire
performance. As these calves continue to grow and perform, as well as change
environments during their transition to the feedlot, a greater spread in weights
between high- and low-growth sires is expected. Even with the smaller weaning
weight spread, we can still clearly see a positive correlation between higher
weaning weight EPDs and heavier actual weaning weights, which is the ultimate
goal of the LiveWiRED project.
Thank you to the Red Angus Foundation Inc. for
sponsoring the LiveWiRED project!
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