Select Sires

Sire Fertility, Part 2
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired Sept. 23, 2004
With Jeff Stephenson,
Professor of Animal Sciences,
Kansas State University

This week' Reproductive Moment is with Jeff Stephenson, Professor of Animal Sciences at Kansas State University. We are picking up where we left off last week where we were talking about the original sire estimate program, ERCR, or estimated relative conception rate and a new sire fertility option that is now offered by a dairy records-processing system in Visalia, California known as AgriTech Analytics.

Like the ERCR, they are provided in terms of a ranking from the most fertile to the least fertile sire and you read them just like you would a proof if you are looking for sires for milk production or various types of type traits. You simply look at the ranking from the top to bottom, and you can choose bulls that are above average or below average, in terms of their fertility.

What’s different, then, using this as opposed to the ERCR?

It is a very similar type of system, but it just provides more accurate estimates of the actual sire fertility. The rankings that are provided in the two systems are going to come out just about the same. One thing that some people forget about is that our dairy sires are a highly select population. When you start playing with averages, you have to realize that they can get you into trouble.

If you can take an average group of cows, like we have on our DHI test, and decide you are going to cull the ten bottom cows, then once you do that and take a new average, you still have some cows for below average. It doesn’t matter what populations you take. You take a population of college professors who supposedly may be a little brighter than the average people, but if half of them retire, and you take an average of what is left, you are still going to have people below average or above average.

You have to be careful when using these types of rankings. You have to realize that these sires have been highly discriminated, highly tested and they represent a very select population of bulls that are very, very capable in terms of siring offspring, that have the kind of genetics that we want for dairy cattle today and that are very highly discriminated in the bull studs to determine those bulls that we think are the very best in terms of having a normal semen quality, and so forth and so on. When you look at a list like that, even the ones on the bottom of the list, which would be considered on average to be less fertile, the real spread between the lowest and highest is only about eight or ten percentage points. That can be considered to be quite a bit, but even the ones on the bottom still offer some real value to the dairy producer in terms of the genetics for milk production and so forth. But they tend to be, on average, a little bit less fertile than the other sires that are available.

The important thing to remember is that sire fertility is only one of the many puzzle pictures that make up the fertility picture, and we don’t want to overemphasize the importance of sire fertility when there are so many other factors that are important in contributing to the success of an A.I. program. It is just one of the factors. Many of the factors we have more control of on the farm in terms of semen placement, thawing semen correctly, feeding cows properly, identifying cows that are not cycling and that have uterine problems that would contribute to lower fertility. It is just one of the puzzle pieces that we have to keep that in mind when considering sires as mates for our lactating cows.

Jeff Stephenson, Professor of Animal Sciences at Kansas State University.

Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751