The Fertility Outcomes of Egyptian Buffalo Cows after Ovsynch and Presynch-Ovsynch Protocols

The present study aimed to compare the reproductive outcomes after the blind application of the standard Ovsynch and Presynch Ovsynch protocols on Egyptian Buffaloes ( Bubalus bubalis ) during the breeding season. Fifty multiparous Egyptian buffalo cows of an unknown stage of the estrous cycle were randomly divided into two groups: 1) the standard Ovsynch protocol (first GnRH (G1) at d0, PGF 2 α at d7 , and second GnRH; G2 56 h later and 2) the pre-synch Ovsynch (G6G-Ovsynch) protocol (PGF 2 α and GnRH 2 days apart 6 days before starting G1 of the standard Ovsynch). Cows were subjected to timed artificial insemination (TAI) 16 and 40 h after the G2 injection in both groups. Blood sampling and ovarian transrectal ultrasonography were performed at three time points, PGF2α, G2, and 2 days after G2. Serum progesterone (P 4 ) (ng/mL) concentrations were significantly higher in the G6G-Ovsynch group than in the Ovsynch group at the time of PGF 2 α and two days after the G2 injection, but they were lower (P ˂ 0.05) at the G2 injection. The Vascularity index of the corpus luteum (CL) and dominant follicle (DF) wall area (%) were higher (P ˂ 0.05) in the G6G-Ovsynch group compared to the Ovsynch group. The ovulatory response indicated by the presence of CL at d7 was significantly higher in G6G-Ovsynch than in Ovsynch (73 vs. 51%, respectively). Moreover, a higher (P ˂ 0.05) pregnancy rate was observed in G6G-Ovsynch than in the Ovsynch group. In conclusion, the blind application of the G6G-Ovsynch improved the ovulatory response in the early stages of the synchronization protocol and raised the pregnancy rates in Egyptian buffaloes.