Vol. 10, Special Issue 5 (2021)

Methods:The peripubertal anestrous Murrah buffalo heifers (Bubalus bubalis) during summer (Jun-Aug; n = 14) and winter season (Dec-Feb; n = 12) were selected at random from herd and the ovaries of the experimental animals were scanned. Subsequently, the animals during each season, were randomly divided into two groups and received either ‘Ovsynch-Plus’ (Group I; summer, n = 7; winter, n = 6) or ‘Modified Ovsynch-Plus’ (Group II; summer, n = 7; winter, n = 6) treatment. The follicular dynamics was monitored by ultrasonography daily during the period of treatment till day 12 and then after insemination at weekly interval i.e., at day 7, 14, 21 and 28 post insemination. All the treated females were inseminated at fixed time on day 12 and 13. Pregnancy was diagnosed by ultrasonography on day 28 after insemination. Administration of eCG increased the number as well as size of dominant follicles (DF) on day 2^nd and 3^rd after injection.

Results:A combination of eCG and GnRH at 3 days apart resulted in formation of CL in 100% animals during summer season and in 96.15% of heifers during winter season. Administration of hCG (on day 3) in ‘Modified Ovsynch-Plus’ treated group resulted in availability of large persistent follicles that were not responsive to GnRH injection given on day 12 of treatment. Only those females conceived who responded by ovulation to eCG/1^st GnRH/hCG and 2^nd GnRH administrations. Conception rate was found to be better in ‘Ovsynch-Plus’ treated heifers compared to that of ‘Modified Ovsynch-Plus’ treated heifers. In conclusion, start of the ‘Ovsynch’ protocol with hCG did not increase ovulation and conception rates in heifers. However, increasing ovulation rate in response to pre-hormonal administration of ‘Ovsynch’ with eCG have a significant effect on conception rate in anoestrous buffalo heifers.