Ovarian and hormonal changes during Ovsynch program

in buffalo-cows (Bubalus bubalis)

A.Ali,¹ A. Kh. Abdel-Razek¹ and S. Fahmy²

¹Dept. Theriogenology, Fac. Vet. Med., Assiut University, Egypt

²Dept. Anim. Prod., Fac. Agriculture, Al-Azhar University, Assiut-branch, Egypt

ABSTRACT

 The objective of the current study was to monitor ovarian and hormonal changes associating ovsynch program in buffaloes. Eight Egyptian buffalo-cows, 52-217 days postpartum were used in this study. Irrespective to the stage of estrous cycle, each buffalo-cow received three injections: GnRH on day 1, PGF₂a on day 8, and GnRH on day 10 with AI 9 and 24h later. Ovarian structures were monitored daily by ultrasound examination. Milk samples were collected from each cow on days 1, 5, 8, 9,10 and 11 for progesterone (P₄) analysis. The 1^st GnRH injection resulted in development and ovulation of a large follicle (DF1) in 7/8 cases. The mean time from injection to ovulation was 2.13 ± 0.4 days. This injection was also successful in synchronizing a new follicular wave 3.22 ± 0.8 days later. The mean P₄ level increased significantly from day one through day eight. By the day of PGF₂a injection (day 8), 4/8 cows showed double CL, 4/8 had single one and 7/8 revealed large follicle (DF2). After PGF₂a injection, the CL regressed in 6/8 animals. The rate of P₄ reduction was much rapid in animals with double CL than in those with single one. After the 2^nd GnRH injection, the DF2 ovulated in 6/8 cases. All ovulation occurred between 24 and 48h after injection. Five of the eight buffalo-cows conceived according to ultrasonographic pregnancy diagnosis one month after AI. In conclusion, this study provided some basic knowledge about the ovsynch program in buffaloes, which might be used to dominate the problem of silent heat in this species.

Key words: estrus synchronization, GnRH, PGF₂a, milk progesterone, buffalo