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Published on: July 8, 2020
Modifying the double-Ovsynch protocol to include human chorionic gonadotropin to synchronize ovulation in dairy
J A Binversie1, K E Pfeiffer, J E Larson
1Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, USA.
Theriogenology
|October 10, 2012
Summary
Replacing gonadotropin-releasing hormone (GnRH) with human chorionic gonadotropin (hCG) in the Double-Ovsynch (DO) protocol did not improve conception rates in dairy cattle. While hCG increased ovulation rates in cows, it did not enhance overall fertility.
Area of Science:
- Veterinary Medicine
- Reproductive Biology
- Animal Science
Background:
- The Double-Ovsynch (DO) protocol is widely used for estrus synchronization and timed artificial insemination in cattle.
- Modifications to hormonal treatments within synchronization protocols are continuously explored to optimize reproductive efficiency.
Purpose of the Study:
- To evaluate the impact of substituting gonadotropin-releasing hormone (GnRH) with human chorionic gonadotropin (hCG) in the initial step of the Double-Ovsynch (DO) protocol on conception, ovulation, and ovarian characteristics.
- To compare the efficacy of GnRH versus hCG in inducing ovulation and influencing luteal function within the modified DO protocol.
Main Methods:
- A randomized controlled trial involving 183 lactating dairy cows and 51 dairy heifers.
- Females were assigned to receive either GnRH or hCG at the initiation of the Pre-Ovsynch (PO) phase of the DO protocol.
- Ovarian structures, ovulation timing, progesterone concentrations, and pregnancy rates were monitored using ultrasonography and blood sampling.
Main Results:
- Conception rates were similar between GnRH- and hCG-treated groups in both cows and heifers.
- HCG administration increased ovulation rates in cows compared to GnRH (77.2% vs. 62.2%).
- Progesterone concentrations were higher 7 days post-treatment in cows receiving hCG compared to GnRH.
Conclusions:
- Replacing the initial GnRH injection with hCG in the DO protocol did not result in improved overall fertility or conception rates in dairy cattle.
- While hCG enhanced ovulation rates in cows, this did not translate to a significant improvement in pregnancy outcomes.
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