Reproductive Management Goals
(Part One)
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired Oct. 6, 2005
With Ray Nebel,
Extension Specialist and Professor of Reproductive Management,
Virginia Tech
Ray, this week we are talking about reproductive goals. Let's start out at goals of days to first service.
Ok, Bill. Normally we start the reproductive process with calving with a voluntary waiting period. How long are we going to give her to recover? Traditionally there have been two voluntary waiting periods, either 45 days from calving to when you want to start, or sixty days. When you look at those two voluntary waiting periods we normally add ten to fifteen days. So if you have a 45-day voluntary waiting period, our average day at first service should be somewhere around 60. And if we have a 60-day voluntary waiting period our average day to first service is going to be about 75.
And looking at the conception rate to first service?
Our conception rate at first service is usually our highest conception rate because it includes the whole herd, which has hopefully predominantly normal cows. We have that group of problem cows that have become a bigger proportion of the second and third services when we get the normal cows bred. So first service is our indicator of how well we can do in an A.I. program. And there are really two different goals: a goal for small herds, and a goal for large herds. I guess a small herd is a changing target, but I would say in today’s U.S. dairy industry that’s 200 cows and smaller. And the goal I would put there would be 40-45 percent, and the large herds, especially out west, when we talk about thousands of cows, the goal there is probably 30 percent. And the difference is really the amount of time we can spend, labor-wise, per cow. It really changes when the cow numbers change.
It probably would be the same for pregnancy rate, two different goals there?
Right. Pregnancy rate is our number of cows that are eligible to get pregnant in a 21-day period, and how many of those cows actually do become pregnant. So it's really a combination of conception rate in our submission rate, where we are talking about heat detection or timed A.I. So, how many cows are eligible to get pregnant? And how many do get pregnant in a 21-day period? For the smaller herd we are looking at a goal of 20 percent or higher pregnancy rate, and for the larger herd we are looking at a pregnancy rate of about 18 percent. That two percent might sound like it's not very much. It might sound trivial, but it's really a big difference.
Culling plays a part in the goal work as well, right?
Sure. Our turnover for reproduction or reproductive failure, or how many cows we can’t get production from after our attempts at both A.I. and natural service, plays a tremendous role in what our records look like. If we cull out a lot of cows, it really kind of masks what we are getting, or it overrides what we were getting on a true reproductive program. We always should look at what the turnover rate, or what the culling rate is, and traditionally that’s been about a third of the herd totally. For reproductive reasons we would like to keep it under ten percent and ideally under eight percent.
Thanks, Ray. We will continue next week with goals of reproductive performance. That’s Ray Nebel, Reproductive Specialist at Select Sires.
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