Impact of three different ovulation synchronization protocols on first-service conception rates in postpartum cows

Abstract

The study was conducted on 60 Holstein dairy cows during 50 and 60 days postpartum in different rural areas in Al-Anbar Province, Iraq. This study evaluated the effects of two ovulation synchronization protocols on postpartum fertility performance compared to the conventional Ovsynch protocol. All cows were treated with GnRH (10.5 µg) and PGF2α (0.150 mg) through three different synchronization protocols: (1) Ovsynch protocol (n=20) as the control treatment [GnRH-7d-PGF2α-48h-GnRH]; (2) GPPG protocol (n=20) as (1), but with an extra dose of PGF2α-24h after the first one. (3) PG+G protocol (n=20) as (2), but with presynchronization treatment using PGF2α and GnRH simultaneously, seven days before the GPPG protocol. All cows were subjected to timed artificial insemination (TAI) 16-24 hours after the final GnRH injection. Ultrasound confirmed the pregnancy at 30-35 d post-TAI. There was no significant difference between the groups (P>0.05) regarding calving interval and open days. Overall, first-service conception rate (FSCR) tends to be significant (45%, P=0.07). Separately, FSCR for groups 1, 2, and 3 were 30, 40, and 65%, respectively. The difference between groups 1 and 3 was significant (P=0.02); however, group 2 did not differ from groups 1 (P=0.50) and group 3 (P=0.11). In conclusion, implementing TAI protocols during the 50-60-day postpartum period lowers the calving interval to standard limits. Furthermore, the PG+G presynchronization protocol significantly enhances FSCR compared to the traditional Ovsynch during the postpartum period.

Keywords

• cattle
• pregnancy rate
• ovsynch