Type of Document Master's Thesis Author Peeler, Iris Dawn URN etd-04262004-163148 Title Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers Degree Master of Science Department Dairy Science Advisory Committee
Advisor Name Title Nebel, Raymond L. Committee Chair Cassell, Bennet G. Committee Member Nickerson, Stephen C. Committee Member Pearson, Ronald E. Committee Member Keywords
- reproductive performance
- timed artificial insemination
- dairy cattle
Date of Defense 2004-04-21 Availability unrestricted AbstractSYNCHRONIZATION AND RESYNCHRONIZATION OF OVULATION AND TIMED INSEMINATION IN LACTATING DAIRY COWS AND HEIFERS
Iris Dawn Peeler
This study was conducted to evaluate the efficacy of intravaginal progesterone (P4) inserts (CIDR) in synchronization protocols combined with timed artificial insemination (TAI) as related reproductive performance. In the first study, heifers were synchronized with CIDR inserts followed by TAI. Heifers in the estradiol cypionate (ECP) group were synchronized with a combination of ECP, CIDR, prostaglandin (PGF2á), and ECP (CIDR-ECP), while the gonadotropin-releasing hormone (GnRH) group was synchronized using a combination of ECP, CIDR, PGF2á, and GnRH (CIDR-GnRH). All heifers were bred at either 48, 56, or 72 hours (h) after CIDR removal. Overall pregnancy rate (PR) for synchronized heifers was 60.1%, and embryo survival rate (ESR) was 98%. Pregnancy rate for CIDR-ECP treated heifers was influenced by artificial insemination (AI) time. In conclusion, ECP or GnRH may be used effectively in a CIDR-based TAI program in heifers. In the second study, cows were synchronized with CIDR devices or Ovsynch. The CIDR group received a combination of ECP, CIDR, PGF2á, and GnRH, while the Ovsynch group was synchronized using a combination of GnRH and PGF2á. Cows were bred at either 0, 8, or 24 h after the final GnRH injection. Overall PR for first service was 30.5% with ESR of 82.8%. Overall resynchronization PR was 35.1% with an ESR of 84.8%. In conclusion, Ovsynch and CIDR-based protocols are equally effective in synchronizing ovulation in a TAI program and resulted in comparable PR.
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