Use of GnRH and PGF for synchronized ovulation and fixed-time inseminations

摘要

Holstein cows and virgin heifers weretreated with GnRH and PGF in a novel 2aovulation synchronization protocol, whichinvolves one fixed-time insemination. Oneinjection of GnRH is given on a Mondaymorning, followed in 7 days with an injectionof PGF . Approximately 32 hr later, ovula- 2ation is induced with a second injection ofGnRH, and one insemination is made 18 hrlater. Control cattle were given one injectionof PGF and inseminated at estrus. Preg- 2anancy rates measured between 28 and 35days after insemination by ultrasonographywere slightly, but not significantly, higher incontrols (52.9%) than in the ovulation synchronizationtreatment (44.3%). This treatmentmay be particularly well suited to cowsin which estrus is rarely observed, as well asfor synchronizing first or repeat services.