Vol. 10, Special Issue 11 (2021)

Author(s):
Hariom, Harpreet Singh, Ravi Dutt, Sonu and Lal Chand Ranga

Abstract:
The study evaluated the efficacy of the (Ovsynch) modified estrus synchronization protocols in combination with different durations of progesterone (P4) therapy (using P4 impregnated intravaginal sponges) during breeding (November-January; autumn season) and non-breeding (May-July; summer season) seasons in Nali×Rambuillet crossbred ewes. Three GnRH-PGF2α-GnRH protocols were employed with modifications in three groups (during one breeding and one non-breeding season) sequentially on days 0, 5, 7 in protocol-A; on days 0, 8, 9 in protocol-B and on days 0, 12, 13 in protocol-C combined with different durations of P4 therapy (5, 8 and 12 days of sponge insertion in protocol-A, -B and -C, respectively). Each experimental group comprised of randomly selected 50 ewes. A total of 5 proven breeding rams in each group were used for mating with the ewes exhibiting estrus. Application of intravaginal P4 sponges resulted in significant increase in serum P4 concentration on the day of sponge withdrawal compared to the day of sponge insertion in each group. On 28th day post-mating, serum P4 concentration was highest in ewes treated with protocol-B during non-breeding (5.03±0.89 ng/mL) as well as during breeding season (6.42±1.66 ng/mL). In conclusion, the modified estrus synchronization protocol with intermediate duration of P4 therapy (8 days, protocol-B) yielded better results [compared to short (5 days, protocol-A) and long-term (12 days, protocol-C) duration therapy]in the ewes in terms of outcome of improvement in serum progesterone profiles.