COMPARISON OF 2 ESTRUS SYNCHRONIZATION PROGRAMS IN A LARGE, CONFINEMENT-HOUSED DAIRY-HERD

Objective-To compare pregnancy rates, seasonal effects, and economic b enefits of 2 estrus synchronization programs for a confinement-housed dairy herd. Design-Prospective cohort study. Animals-200 lactating Hol stein cows. Procedure-Cows eligible for breeding were palpated per rec tum and randomly assigned to 2 treatment groups during 4 seasonal peri ods. Cows in one group (Ovsynch) received injections of gonadotropin r eleasing hormone (GnRH) on day 0, prostaglandin F-2 alpha on day 7, an d a second injection of GnRH on day 8. in the other group (PP) that ha d a palpable corpus luteum were given prostaglandin F-2 alpha. Estrus detection was not performed on the Ovsynch cows, which were artificial ly inseminated at a predetermined time after the second GnRH injection , Cows in the PP group were observed for signs of estrus, and only tho se that were detected in estrus were inseminated. Results-Pregnancy ra tes and insemination rates were significantly improved for cows in the Ovsynch group, compared with cows in the PP group. Clinical Implicati ons-The Ovsynch program was an economically advantageous method for co ntrolling reproduction that resulted in pregnancies without the need f or estrus detection.