Select Sires

Heat Detection (Part 3)
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired Nov. 27, 2003
With Ray Nebel,
extension specialist and professor of reproductive management,
Virginia Tech

This week’s Reproductive Moment is with Ray Nebel, extension specialist and professor of reproductive managements at Virginia Tech. Ray, one dairy producer noted when he started breeding cows by A.I. that more cows showed heat at night. Is this true and is there any research on this?

Traditionally we use days open, that would measure days from calving to when she becomes pregnant again. And, again we would measure services per conception or breedings per conception, which is just the number of breedings it takes to get a cow pregnant. But, a new measurement here is now pregnancy rate, which has just come out in the past few years, which is more current measurement because it measures every 21 days, what cows get pregnant every 21 days.

Would that be the recommendation you would choose?

Well, the pregnancy rate recommendation is one that we can follow to say, what have we done recently. It basically just takes the cows, what cows are eligible to become pregnant, and what cows do we get pregnant every 21 days. So, it allows you to see changes in the program, or if something has changed as far as management, or temperature, or anything on the farm – it allows you to see that, where some of our traditional measures of reproductive performance took twelve months to average, and that took a long time to see a change. So, if you are really looking to measure what is going on today, pregnancy rate is the way to do it.

Is pregnancy rate basically heat-detection rate multiplied by conception rate?

That is correct. Pregnancy rate is again, the eligible cows that are out there to become pregnant, and how many of those would get pregnant. So, it is how many do we catch in heat, or how many do we put semen in, how many do we service and of those that we service, how many of them get pregnant. An easy way to think of it, it is the heat-detection rate times the conception rate.

This is widely used to calculate the 21-day rate?

Most of the records processing centers do have a pregnancy rate report. The one that I am most familiar with out of Raleigh, the DR Mets report, they have it so that you can get it by lactation number, pregnancy rate by lactation number, pregnancy rate by days-in-milk, pregnancy rate by service number. It is also available from most of the other processing centers, such as Provo and Dairy Comp, so almost all the major processing centers, that they process records at, that the pregnancy report has become a standard report.

Great. And, for more information on that I am sure they can contact their reproductive specialist and they would be glad to help on that.

Select Sires has a lot of information on pregnancy rates, as do the processing centers and most veterinarians could also get you up-to-date and up-to-speed on pregnancy rates.

Thank you, Ray. That is Ray Nebel, extension specialist and professor of reproductive Managements at Virginia Tech.

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