Advisor

Larson, Jamie E.

Committee Member

Rhinehart, Justin D.

Committee Member

Ryan, Peter L.

Date of Degree

1-1-2011

Document Type

Graduate Thesis - Open Access

Degree Name

Master of Science

College

College of Agriculture and Life Sciences

Department

Department of Animal and Dairy Sciences

Abstract

The objectives of this study were to determine whether conception, ovulation rates, presynchronization rates, or follicle and CL characteristics were altered after modifying the Double-Ovsynch (DO) protocol to include human chorionic gonadotropin (hCG) compared to the conventional DO protocol in dairy heifers and lactating dairy cows. We hypothesized that replacing the first injection of gonadotropin releasing hormone (GnRH) in the DO protocol with hCG would increase the proportion of females that ovulate, thus improving the presynchronization rate leading to increased conception rates. Ovulation rates were increased in cows administered hCG compared to GnRH, but subsequent synchronization, and conception rates did not differ between treatments. A greater proportion of hCG-treated cows tended to fail to have undergone luteolysis compared to those treated with GnRH. In conclusion, no improvement in overall fertility was achieved by replacing the first injection of GnRH in the DO protocol with hCG.

URI

https://hdl.handle.net/11668/17842

Comments

presynchronization||hCG||Double-Ovsynch

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