The Effects on Follicular Dynamics Caused by Changing the Application Time of PGF2α and GnRh in the Cosynch Protocol Administered in Montofon Cows with Estrus

Abstract

The objective of this study was to investigate how follicular dynamics are affected by changing the initial injection times of PGF2α and GnRH in the Cosynch protocol in Montofon cattle that have been administered presynchronization. Initially, all cattle whose corpus luteum was identified were administered an injection of PGF2α. Six days after estrus was identified, the Cosynch protocol was started. In keeping with this, Group I (GI; n=9) was administered GnRH on day 0 and PGF2α 7 days later. Fifty-six h later, artificial insemination was performed and GnRH was injected. In the second group of cows (GII; n=10), PGF2α was administered in the Cosynch protocol 8 days after the first GnRH injection. Fifty-six h later, artificial insemination was performed and GnRH was injected. Development of the follicle and the corpus luteum was monitored each day with ultrasonography. On days 6, 7 and 8 of the procedure, a statistically significant difference in the follicle diameters was identified between the groups (P 0.05). In conclusion, we determined that for cattle administered the Cosynch protocol on the 6th day of the sexual cycle, extending the application time of PGF2α by one day in did not affect the size of the Graafian follicle.