Did you notice something different when you looked at the latest sire proof data?
If not, you should have. The new Sire Conception Rate (
The tool also features data from three of the four major dairy records-processing centers — a major enhancement from previous evaluations that makes the evaluation national in scope.
Combine that with a tweaked computer model, and the tool offers increased accuracy in bull-fertility measurements — and a means to improve the fertility of your overall reproductive program. Here's how to use it.
1. Generate bull list
Using your selection criteria, like net merit, generate a list of bulls to evaluate. Rank them according to how they fit your dairy's (and individual cow) needs.
2. Evaluate bull fertility.
Next, take a look at how well the bulls score using the
You use this measurement similarly to how you used ERCR. The exception is that
To put this in conception-rate terms, a bull with an
3. Select bulls
Now that you know what these bulls will do for your herd's fertility, select bulls to use on your dairy that fit your overall selection criteria and offer increased fertility. Remember that while this tool will help improve your reproductive program, you must still follow proper semen storage, handling and breeding techniques.
Which bulls will receive a
The new sire conception rate scores will be available for bulls that have active A.I. status and are less than 13 years old.
Return rate vs. conception rate
Previously, bull fertility evaluations were based on 70-day non-return rates. that means, if a cow was not resubmitted for insemination 70 days after that first breeding, she was assumed pregnant. These data were factored into a bull's Estimated Relative Conception Rate.
One problem with this is that a cow may be returned for insemination after day 70, like day 72, for example. However, the initial mating was still considered a success because she had not required breeding before day 70, says Duane Norman, research leader with the USDA Animal Improvement Programs Laboratory in Beltsville, Md.
The new Sire Conception Rate uses cow conception rate as the basis for its analysis, which increases data accuracy. "A cow must be pregnant using this measurement," says
The two traits are highly related when derived from the same cows, so the change won't affect bull fertility rankings too much, he adds, but the additional inseminations do increase data reliability considerably.