Influence of fecundity gene on oestrus synchronization and gonadal steroid levels in booroola carrier and Non-Carrier ewes

Prolificacy in Garole sheep is due to the effect of a single point mutation in the bone morphogenetic protein receptor 1B (BMPR-1B) and expressed in the granulosa cells and oocytes. The GMM (25% Garole-75% Malpura) sheep was developed by FecB introgression from Garole sheep. An experiment was conducted in the major breeding season (July-August, 2016) to study the oestrus synchronization response and plasma progesterone and oestradiol hormone concentrations in prolific GMM ewes (FecBBB), non-prolific GMM (FecB++) and Malpura ewes (FecB++). GMM strain was developed from Malpura (75%) and Garole (25%) breed so considered as control group for estrus response. A total of 28 ewes (carrier GMM (n=9), non-carrier GMM (n=10) and Malpura (n=9)) were synchronized with progesterone impregnated intravaginal sponges. It was observed that the proportion of ewes that exhibited oestrus did not differ significantly between the carrier and non-carrier GMM ewes; however, the oestrus response was early in carrier GMM compared to non-carrier GMM and Malpura ewes. The interval time for the onset of oestrus was non-significantly lower in carrier GMM (32.00±5.93) as compared to noncarrier GMM (36.00±3.70h) and Malpura (39.43±3.43h) ewes. The duration of oestrus did not differ significantly between the genotypes. The plasma progesterone concentration was significantly (P<0.05) higher in carrier GMM ewes (2.73±1.29ng/ml) as compared to non-carrier GMM ewes (1.28±0.62ng/ml). The oestradiol concentration was significantly higher (P<0.001) in non-carrier GMM (181.95±30.38pg/ml) as compared to carrier GMM ewes (124.43±15.87pg/ml). The results indicated that the FecB mutation alters the circulating concentration of progesterone and estradiol in Booroola carrier GMM (FecBBB) ewes.