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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #101542
Title: SYNCHRONIZATION OF OVULATION USING HCG OR GNRH WITH THE CO-SYNCH PROTOCOL IN SUCKLED BEEF COWS

Author
item SALVORSON, ROBIN - COLORADO STATE UNIVERSITY
item WHITTIER, JACK - COLORADO STATE UNIVERSITY
item SCHAFER, D - COLORADO STATE UNIVERISTY
item SCHUTZ, D - COLORADO STATE UNIVERSITY
item DOWNING, E - COLORADO STATE UNIVERSITY
item POLMEROY, T - COLORADO STATE UNIVERSITY
item Geary, Thomas

Submitted to: Beef Research Report
Publication Type: Proceedings
Publication Acceptance Date: 4/1/1999
Publication Date: N/A
Citation: SALVORSON, R.R., WHITTIER, J.C., SCHAFER, D., SCHUTZ, D., DOWNING, E.R., POLMEROY, T., GEARY, T.W. SYNCHRONIZATION OF OVULATION USING HCG OR GNRH WITH THE CO-SYNCH PROTOCOL IN SUCKLED BEEF COWS. BEEF RESEARCH REPORT. COLORADO STATE UNIVERSITY. 1999. p. 69-74.

Interpretive Summary: Primaparous and multiparous cows (n=467) from two locations were used to evaluate the effect of 48-hour calf removal and the use of human chorionic gonadotropin (hCG) in place of GnRH with the CO-Synch protocol. Treatments included GnRH, GnRH + calf removal, hCG, and hCG + calf removal. Pregnancy rates were higher (P<.05) for GnRH treated cows (48%) compared to hCG treated cows (34%) regardless of calf removal. Calf removal had no effect (P>.1) on pregnancy rates. Cows that received hCG had a higher (P<.05) incidence of short cycles following timed AI and a higher incidence of persistent corpora lutea at the time of insemination. We conclude that hCG is not a suitable replacement for GnRH with the CO-Synch protocol.

Technical Abstract: Primaparous and multiparous cows (n=467) from two locations were used to evaluate the effect of 48-hour calf removal and the use of human chorionic gonadotropin (hCG) in place of GnRH with the CO-Synch protocol. Treatments included GnRH, GnRH + calf removal, hCG, and hCG + calf removal. Pregnancy rates were higher (P<.05) for GnRH treated cows (48%) compared to hCG treated cows (34%) regardless of calf removal. Calf removal had no effect (P>.1) on pregnancy rates. Cows that received hCG had a higher (P<.05) incidence of short cycles following timed AI and a higher incidence of persistent corpora lutea at the time of insemination. We conclude that hCG is not a suitable replacement for GnRH with the CO-Synch protocol.