Abstract

Experiments have shown human chorionic gonadotropin (hCG) to be more effective than GnRH as a means to induce ovulation of folli-cles. Dosages used, however, have differed greatly among experiments. A study was per-formed to determine the minimum effective dose of hCG needed to induce ovulation of ovarian follicles in dairy cows. Ovaries of Holstein cows were mapped by using transrec-tal ultrasonography 7 days before a bi-weekly pregnancy diagnosis. Cows were assigned randomly to treatments of saline, 100 μg of GnRH (2 mL of Fertagyl, Intervet, Inc., Mills-boro, NJ), or 500, 1000, 2000, or 3000 IU of hCG (0.5, 1, 2, or 3 mL of Chorulon, Intervet, Inc., Millsboro, NJ). Ovarian structures were monitored again 7 days later, and the propor-tion of cows, and proportion of follicles ≥8 mm in diameter, that ovulated were recorded. A dose of at least 1000 IU of hCG resulted in a greater ovulatory response than saline, GnRH, or 500 IU of hCG.; Dairy Day, 2006, Kansas State University, Manhattan, KS, 2006;

Keywords: Dairy Day, 2006, Kansas Agricultural Experiment Station contribution, no. 07-118-S, Report of progress (Kansas State University. Agricultural Experiment Station and Cooperative Extension Service), 965, Dairy, GnRH, hCG, Ovulation

How to Cite:

Buttrey, B., Burns, M. & Stevenson, J. S., (2006) “Ovulation potential of human chorionic gonadotropin versus GnRH”, Kansas Agricultural Experiment Station Research Reports 1(2), 32-33. doi: https://doi.org/10.4148/2378-5977.3157