Select Sires

Solutions to Improve Reproduction
(Part One)
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired June 16, 2005
With Jeff Stephenson, professor of animal sciences,
Kansas State University

Today’s Reproductive Moment is with Jeff Stephenson, professor of Animal Sciences at Kansas State University. Jeff, this week we are talking about solutions to improve reproduction. One of those is the individual fertility of the cow.

Many of the factors related to getting cows pregnant are related to individual cow fertility, because every cow has inherent fertility that may be different from another cow. That inherent fertility sometimes makes her more capable of conceiving than some of her herd mates.

Also her A.I. mate.

That is something we are starting to look at in more detail these days. We know that there are differences in sire fertility. There are a number of different systems out there that estimate sire fertilities. Some are based on non-return rate. Some are actually based on confirmed pregnancies. Basically, what we are seeing is that there is about an eight to ten percentage point spread in sire fertility. We have some sires that are capable of producing higher conception rates than other sires, so one ought to consider using those higher-fertility sires when he has an opportunity to do so. When looking at two bulls that have equal merit for the important traits we are going to select for -- for example, milk yield -- if they are equal there and one is a high-fertility bull, then you choose that sire which has the higher fertility.

We have talked, in past Reproductive Moment sessions, about proper semen handling. What can you tell us about that?

There is not anything really new about proper semen handling, but what is important to think about there is whether we are thawing semen correctly, and protecting those thawed sperm cells from the cold-shock that occurs even in summer temperatures. When you thaw the semen at 95 degrees and it is 60 to 70 degrees out, there is still the potential for the sperm cells to cool down if one doesn’t protect them and try to maintain them at that thawing temperature until they are inside the cow. The proper handling -- moving straws of semen from one liquid nitrogen refrigerator to another, all these kinds of things -- is really important to make sure we have as high a quality semen at the farm when we are ready to thaw it as it was when it left the semen-producing business or the stud.

You have to have the timing and placement of that too.

That's correct. Placement of the inseminate is very important and that is all related to the expertise of the A.I. Technician. We know that all A.I. Technicians are not created equal. Some do a better job than others, and studies have demonstrated that those who make sure that they penetrate the cervix, and place the semen into the uterine body, will always have higher conception rates than those who do not penetrate the cervix. That is something that occasionally even professional technicians will have difficulty with in a few cows. When we teach students we always want to make sure that we teach them that we place the semen beyond the cervix into the uterine body, or up into either uterine horn a little way is still not a problem because fertility is equal to that of putting it into the uterine body.

We will continue next week. That is 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