Select Sires

Reproductive Management Tools (Part One)
Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio Which Aired Nov. 4, 2004
With Jeff Stephenson,
Department of Animal Sciences,
Kansas State University

This week’s Reproductive Moment is with Jeff Stephenson from the Department of Animal Sciences with Kansas State University. Jeff, this week we are talking about some tools of Reproductive Management on dairy farms. One is to synchronize ovulation before the first A.I. breeding with Ovsynch®.

Yes, that is probably the most common reproductive tool that people are using today on dairy farms to synchronize ovulation in cattle. It can be used a number of ways, one way that dairy farmers are using it is to synchronize the ovulations for all cows as they breed them the first time after they calve. So, they are setting those cows up with an injection of GnRH, or with seven days of prostaglandin and 48 hours later giving GnRH again; either breeding then or within the next 24 hours. Or they are choosing to heat detect cows for a period of time and any cow that has not been inseminated by 90 or 100-days in milk, they may then take those cows in small groups or clusters and use the Ovsynch protocol on those cows.

Let’s talk about improving on Ovsynch by re-synchronizing estrus cycles with pre-synch plus Ovsynch.

Yes. That is fast becoming somewhat more common on dairy farms. The primary motivation for pre-synchronizing estrus cycles before using the Ovsynch protocol is that we improve the fertility of cows prior to using Ovsynch, and the reason for that is by using two injections of prostaglandin, given 14-days apart, with the second injection given 12 to 14-days before you begin the Ovsynch protocol. What we are doing is setting up cows so that we have a high proportion, about 70 percent of the cows, will be between days five and twelve of the estrus cycle when we start the Ovsynch protocol. In so doing, what we have seen in work here in Kansas and other work in a couple of other places around the country, that pregnancy rates to the timed insemination during the Ovsynch protocol are improved by anywhere between six to fourteen percentage points. This takes advantage of the fact that we are getting those cows in a more fertile stage of the estrus cycle to start the Ovsynch protocol so that we can better time the follicular development and corpus luteum regression prior to using timed breeding that is associated with the Ovsynch protocol.

Talk a little more about what the Ovsynch protocol does.

The first injection of GnRH causes about 60-some percent of the cows to ovulate a follicle so that they form a secondary corpus luteum. Seven days later we then regress that corpus luteum, which may be a secondary corpus luteum, and the original corpus luteum, which the cow spontaneously formed after she was last in estrus so that we’ve timed follicular growth with the regression of the corpus luteum before she comes into what would be an estrus period where we time breed her.

Thank you Jeff. Next week we will continue our discussion with more Tools of Reproduction Management on dairy farms. That is Dr. Jeffrey Stephenson from the department of animal sciences at Kansas State University.

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