  BeefTalk:
Data Collection Gives Accuracy to Trait Selection in Beef Cattle
By Kris Ringwall, Extension Beef Specialist,
NDSU Extension Service
Beef cattle breeding creates many possibilities. Each cell contains 60
chromosomes or trains that need to be running smoothly to have a healthy animal.
It is easy to see why such a wide variance exists in traits across and within
breeds.
Collecting data can minimize risk when it comes to selecting new herd sires.
Perhaps the simplest example of this is in horned or polled cattle. If a bull
has horns, for all practical considerations the genetic expression is the same
as his genes. The bull carries two copies of the horn gene. However, if a bull
is polled, he could sire a horned calf or a polled calf. Just by looking at a
polled bull, you do not know.
Once you use the bull on cows, you can develop some confidence if he has one
copy or two of the polled gene. If all of his calves are polled, especially when
bred to horned cows, we know he carries two copies of the polled gene and no
horn gene. If he sires a horned calf, he carries one copy of the polled gene and
one copy of the horned gene. You would know this because you recorded the data.
The same process could be used in trait selection like birth weight. A common
question is whether a birth weight expected progeny difference (EPD) with the
value of one is more reliable than an actual birth weight of 80 pounds. Research
shows both are suitable but the EPD appears to be a better indicator. How do I
know? Record-keeping software (like CHAPS) and breed associations’ base
numbers on data collection provide information.
A producer cannot see the master cargo list for the chromosome trains in
bulls but the actual birth weight of the animal, his siblings and his parent are
indicators of the potential birth weight. These indicators will help a producer
determine if the traits sought are loaded up on those chromosomes.
Many producers do not believe a computer number is a better indicator than
the actual number. Their main concern is that the bull they buy and cow they
have at home will deliver a calf next spring, born without assistance. (Some
breed associations have actually developed alternative EPDs to aid in the actual
selection for calving ease rather than using birth weight as an indicator.)
EPDs fine-tune the ability of the computer to predict based on all data
available. The wider the spectrum of data collected, the more accurate the
outcome--and the greater the likelihood that the chromosomes will be
synchronized according to my liking. In other words, I look at all the data
available to predict whether the package I want is loaded up on the chromosome
train of the bull I’m considering.
This logic may not convert anyone that already does not fully appreciate the
value of a computer-predicted number because there is a penchant in the bull
business: what I see is what I want. In other words, I can see the bull, he was
weighed at birth and he will work.
That’s reasonable thinking, but what you see is not what you always get.
That is why record-keeping systems try to include more data, ending up with one
number to keep the selection process simple, yet predictable.
We would hope we could select a bull (without having to find out for
ourselves) that sires calves that will not need assistance at calving time.
However, birth weight is like buying a polled bull: You are not sure exactly
what the bull will sire. He needs to be tested. Just by looking at a bull’s
head for horns or looking at his birth weight, you can only guess. But if his
ancestors are looked at, at least on paper, plus his other relatives, plus
knowing what the bull himself looks like, you can make a better guess about how
a bull’s chromosome train is loaded and how that load (genetic makeup) will
work for you.
The birth weight EPD is the best estimate of a bull’s effect on birth
weight, or calving ease. Use the numbers and some common sense to predict the
chromosome cargo and beat the odds.
Enjoy your bull buying and may you find all your ear tags.
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 BT0130.
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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
Predicting Genetically Polled or Horned Cattle
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Gene on Gene on Calf
1st Chromosome 2nd Chromosome Predictability
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polled polled high
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polled horns low
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horns horns high
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