Conception Rate Factors
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired Oct. 5, 2006
With Ray Nebel,
Senior Reproduction and Herd Management Specialist, Select Sires Inc.

Ray, this week we’re talking about factors that affect conception rates.

The first factor is that we want to breed heifers as soon as possible because heifer-rearing costs are about 20 percent of the total operation. Therefore, proactive reproductive management programs shorten that interval from the time of birth to parturition. The target is really to start breeding about 12 months of age, but we kind of look at when the cycling occurs.

And when does that occur?

Well, we’ve done a study recently where we took a weekly blood sample to look at when does the first CL form. In Holstein heifers, it averaged about 11 months of age and about 660 pounds or 48 inches at the withers. In contrast, in Jerseys this occurred at nine months of age; they weighed about 425 pounds and were 42 inches at the withers, or were about six inches shorter. So you can see that Jerseys start puberty much younger and at a lighter weight because they are a smaller breed, and also they are about a foot shorter. Another interesting fact is that we added crossbreeds to the study and the Jersey-Holsteins were exactly in the middle of the two purebred breeds.

Ray, you’ll be talking about this in Colorado coming up. What other points will you be discussing?

The other point we are talking about is using gender SELECTed semen. Last week I was in western Kansas and visited 13 farms that ranged from about 2000 cows to 6000 cows. We also visited a few feed lots. Last year two of the farms tried the gender SELECTed semen and had excellent results, so the buzz last week was that almost every farm we went to was, how can they incorporate gender SELECTed semen. So the last point that I’ll be making in my presentation is that we have waited a long time for this product and now we do have a product currently on the market—Select Sires has about 25 bulls available, the conception rate is at 70-75 percent of what we expect of conventional semen, but the heifer ratio is coming out right at what we expected at about 90 percent heifers. It’s worked out really well. I think what is exciting now is the dairymen bred the heifers last year—there was some reservation because we did get a lower fertility—but now that those heifers are calving this fall and we are getting a 90 percent female heifer crop, the heifers are coming in just where we expected. All these dairymen are pretty exited and the increased interest in the gender SELECTed semen has been generated by these initial results. Currently we produce and we’re selling almost keeping up with production. Across the country I would say 30 percent of our customers either tried or are currently looking into trying it, so somewhere around one out of three have either purchased or inquired about the use of gender SELECTed semen.

Well said, Ray. Any final comments?

I guess, Bill, the only thing I would like to close on is that heifers really ought to be where we focus our AI program, not neglect an AI program. They are easier to manage, they have a higher conception rate; it just makes a whole lot of sense. As far as our genetic potential, it should be best in our youngest animals so really the focus should be put on putting our best semen, our gender SELECTed semen, in our youngest animals, which is our heifer breeding program.

Thanks, Ray. That’s Ray Nebel, senior reproductive management specialist at Select Sires.