Abstract:
The aim of the present work was to study the effect of either gonadotrophin-releasing hormone (GnRH)?prostaglandin PGF2??GnRH (G?P?G) or equine chorionic gonadotrophin (eCG)?PGF2??GnRH (eCG?P?G) regimes with or without intramuscular injection of ergometrine maleate (Methergin) within 24 h post partum on the uterine involution, initiation of post partum cyclicity and subsequent reproductive performance of buffalo. A total of 60 parturient Egyptian buffalos (2?4 lactations) were used to conduct this study. The involved animals were allotted into two main groups (A and B), each with 30 animals, on the basis of whether buffalo cows received an i.m. injection of 3 mg of Methergin within the first 24 h post partum (A, Meth. T) or not (B, Meth. NT). Each main group was subdivided into three subgroups: A1, A2 and A3 in case of A and B1, B2 and B3 in case of B. The G?P?G regime was applied on both A1 (Meth. T) and B1 (Meth. NT) buffalos, where each individual received two i.m. injections of 0.020 mg GnRH analogue (buserelin) at Days 18 and 33 post partum with i.m. injection of 25 mg PGF2? (Dinoprost) in between at Day 25. The eCG?P?G regime was applied on both A2 (Meth. T) and B2 (Meth. NT) buffalos, where each individual received i.m. injection of 1000 IU eCG, 25 mg of PGF2? (Dinoprost) and 0.020 mg of GnRH analogue (buserelin) at Days 8, 18 and 25 post partum, respectively. The A3 subgroup (Meth. T, alone) was control for A1 and A2 subgroups and the B3 subgroup was the non-treated control for all subgroups. There was a significant (P < 0.01) decrease in the days required for complete uterine involution in subgroups A1, B1 and A3, indicating the enhancement of uterine involution. The post partum cyclicity was initiated earlier in all of the treatment regimes applied in the present study, as was indicated by significant (P < 0.01) decrease in the days to first ovulation in these subgroups compared with the non-treated control subgroup. The reproductive performance of treated buffalos improved as was shown by the significant (P < 0.01) decrease in days to first service, days open and calving interval. It is concluded that enhancement of uterine involution and/or earlier initiation of post-partum cyclicity improve the reproductive performance of buffalos.