Abstract

Lactating beef cows (n=360) were synchronized using the Cosynch procedure; 100 μg of GnRH (day −7) followed in 7 days by 25 mg of PGF2α(day 0). A used intravaginal progesterone insert (CIDR-B) was inserted on day −7 and removed at the time of PGF2αadministration. Cows were assigned to a 2 x 2 factorial arrangement of four treatments: 1) insemination beginning at 48 vs. 60 hours after PGF2αand 2) administration of a second, 100 μg injection of GnRH or an equivalent volume of saline immediately after timed AI. Timed AI at either 48 or 60 hours after PGF2αin a Cosynch + CIDR protocol was equally effective. Administration of GnRH at timed AI improved conception in all cycling cows and in some noncycling cows, depending on their progesterone status.

Keywords: Cattlemen's Day, 2002, Kansas Agricultural Experiment Station contribution, no. 02-318-S, Report of progress (Kansas State University. Agricultural Experiment Station and Cooperative Extension Service), 890, Beef, Ovulation synchronization, Beef cows, Timed AI, GnRH, CIDR

How to Cite:

Johnson, S. K., Harmoney, K. R. & Stevenson, J. S., (2002) “Timed insemination of suckled beef cows after ovulation synchronization with Cosynch + CIDR”, Kansas Agricultural Experiment Station Research Reports 1(1), 121-123. doi: https://doi.org/10.4148/2378-5977.1775