  BeefTalk:
AI Sire Selection Criteria Aids in Building a Uniform Cow Herd
By Kris Ringwall, Extension Beef Specialist,
NDSU Extension Service
The mature cows are due March 10 and the heifers are well over half done
calving. Although calving is the focus of our energy right now, we are also
planning another breeding season. Our goal is to have the cows in shape and
cycling within 60 days of calving so we can rebreed them within 80 days of
calving.
For those herds in which the cows are bred at a synchronized time, many cows
need to be cycling before the 80 days. While you pencil the nutritional program
and check the condition score of the cows, the you also need to place the semen
order if you plan on artificially breeding any of the cows.
For the past nine years, the North Dakota State University Dickinson Research
Extension Center has artificially bred all cows and heifers primarily to Angus
artificial insemination bulls. Now is the time those AI bulls need to be
selected. In picking bulls, you can begin to understand why numbers, i.e.,
performance records, are not always easy to understand.
Our goal has been to maintain a consistent herd of medium-framed cows that
produce fast-growing calves suitable for retained ownership. The cows are AI
bred to Angus bulls and then naturally exposed to Hereford or Red Angus bulls.
The result of nine years of AI has been a relatively uniform set of cows.
The criteria for bull selection has varied slightly, however. Throughout the
years we’ve stressed acceptable birth weight with moderate growth along with a
positive influence on marbling and rib eye area.
Seventeen bulls have had a significant impact on the brood cow herd, siring
more than 33 percent of the cow herd. These bulls have produced almost 596
calves, with 127 daughters in the herd. All the bulls were originally selected
for birth weight EPDs (Expected Progeny Difference) of less then 2 pounds.
Since EPDs change, two bulls have exceeded the criteria slightly, with the
overall range in birth weight EPDs being a minus 2 pounds to a positive 2.1
pounds. The average calf weight has been 83.8 pounds from the AI sire pool,
while the herd average was 91 pounds in 2002.
We’ve had many conversations about using EPD’s for aiding calving difficulty.
For us, capping Angus EPD birth weight values at 2 pounds has truly aided in
keeping birth weight in line with the management expectations of assisting very
few heifers and no mature cows at birth.
The other criterion, post birth growth, has also been enhanced by good sire
selection. The range of weaning weight EPD values for this same pool of bulls
was plus 24 pounds to plus 48 pounds. The calves from these sires averaged 566
pounds at 205 days of age, while the total herd averaged 558 pounds at the same
age. The resulting calf frame score was a 5, a medium-framed calf.
Often, looking at a set of numbers can be frustrating and the untrained eye
has great difficulty picking out trends or patterns within the data set.
Although the data may be hard to see, the Center's selection criteria for high
accuracy Angus AI bulls has successfully reduced birth weight and increased
weaning weight. Perhaps the real sign of a successful breeding program is that
nothing stands out.
If all the calves and cows blend into the pasture as well as the data set,
that may be the best sign of good selection. The Center considers the AI program
a success, not only in the ability to get cows settled, but, additionally, as a
valuable tool in steering the herd's genetics. Those genetics are the building
blocks of any herd.
Your comments are always welcome at www.BeefTalk.com.
For more information, contact the North Dakota Beef Cattle Improvement
Association, 1133 State Avenue, Dickinson, ND 58601 or go to www.CHAPS2000.COM
on the Internet. In correspondence about this column, refer to BT0133.
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Source: Kris Ringwall, (701) 483-2427, kringwal@ndsuext.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu
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Graphic --
Range in EPD Values and Associated Performance
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Range in birth weight EPDs -2 to +2.1
Average herd birth weight 83.8 pounds
Range in weaning weight EPDs +24 to +48
Average herd 205 day weaning weight 566 pounds
Range in yearling height EPDs -0.1 to +0.9
Average herd frame score 5
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NDSU Research Extension Center using high
accuracy AI Angus Bulls
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