Abstract
Our objective was to determine the effectiveness of exogenous progesterone in the form of an intravaginal insert (controlled internal drug release, CIDR) in conjunction with an ovulation synchronization protocol in lactating dairy cows. Cows received a Presynch protocol (two injections of prostaglandin F2α[PGF2α] 14 days apart) beginning 30 and 36 days in milk, respectively, in two herds. Cows were inseminated after the second Presynch injection when estrus was detected. Remaining cows were treated with the Ovsynch protocol, and alternate cows were assigned randomly to receive a progesterone insert(CIDR). Blood was collected, and body condition scores (BCS) were assigned to treated cows. Pregnancy status was confirmed by palpation on day 38 post timed AI (TAI) and verified again 4 weeks later. Progesterone increased conception rates in treated cows when compared with controls (38 vs. 24%), but did not differ from early inseminated cows(38%). Pregnancy loss was numerically less in progesterone-treated cows than in controls(4.4 vs. 11.8%).; Dairy Day, 2007, Kansas State University, Manhattan, KS, 2007; Dairy Research, 2007 is known as Dairy Day, 2007
Highlights
Fate of a dairy cow lies in her ability to reproduce; in an constantly changing dairy industry, reproductive performance has dramatically declined
Our objective was to determine the effectiveness of exogenous progesterone in the form of an intravaginal insert in conjunction with an ovulation synchronization protocol in lactating dairy cows
Remaining cows were treated with the Ovsynch protocol, and alternate cows were assigned randomly to receive a progesterone insert(CIDR)
Summary
Fate of a dairy cow lies in her ability to reproduce; in an constantly changing dairy industry, reproductive performance has dramatically declined. As a means to manage reproductive programs, ovulation-synchronization protocols were developed. Variations of the Ovsynch protocol have been tested to synchronize ovulation by altering timing of gonadotropin releasing hormone (GnRH) and PGF2α injections. Because GnRH is used to control follicular development and induce ovulation of a dominant follicle and PGF2α causes regression of the corpus luteum (CL), timing of injections can further improve fertility when used at certain stages of the estrous cycle. Progesterone prevents the return of estrus and is used to synchronize estrus.
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