Evaluation of the efficiency of estrus synchronization protocols combined with natural service and ultrasonography on ewe reproductive performance during non-breeding season.

BACKGROUND

Estrus synchronization is an important assisted reproductive technology to improve the reproductive performance in ewes. Various protocols have been used with variable success rates, however; literature regarding field applicable estrus synchronization is meagre.

AIMS

The present study was designed with the aim to evaluate the estrus synchronization protocols on reproductive performance in ewes using different hormones.

METHODS

Experimental ewes were divided randomly into three groups (n=15). Ewes of all groups received intravaginal sponge for 12 days. Subsequently, NP-GnRH and NP-eCG groups received 8 µg of buserelin acetate or 200 IU of eCG intramuscularly, respectively on day 12 whereas NP-Insulin group received insulin 0.2 IU/kg body weight subcutaneously for three consecutive days started on the day of sponge removal. Estrus detection commenced 24 h after sponge removal in NP-GnRH and NP-eCG groups and 24 h following last injection of insulin in NP-Insulin group. The ewes in estrus were separated and pen mated. The conception rate was determined by ultrasonography.

RESULTS

The estrus response and conception rates were 71.43, 92.86 and 53.85%, and 70.00, 84.61, and 71.43%, respectively in NP-GnRH, NP-eCG, and NP-Insulin groups. The lambing rates were the same as the conception rates. The single and multiple birth rates were 71.41, 36.36 and 60.0%, and 28.57, 63.64, and 40.0% whereas prolificacy was 128.57, 190.91, and 140.00%, respectively in NP-GnRH, NP-eCG, and NP-Insulin groups.

CONCLUSION

In conclusion, the estrus synchronization protocol including intravaginal progesterone sponge and eCG was found to be more effective under field conditions.