The effect of medroxyprogesterone acetate with or without eCG on conception rate of fat-tail ewes in out of breeding season.

Abstract

Many protocols of estrous synchronization in ewes have been developed in the last few decades. The aim of this study was the effect of intravaginal progestogen, medroxyprogesterone acetate (MPA), sponges (a progesterone analogue) with or without equine chorionic gonadotropin (eCG) in out of breeding season of fat-tailed Iranian Shaal breed anestrus ewes to estimate the conception rate in suburb of Tehran-Iran. In total, 50 non-cyclic ewes out of 85 ewes with < 0.05ng/ml progesterone (P4) and aged 2 to > 7years old were selected for out of breeding season program in May-June 2018. They were distributed into two groups (control and treatment). The treatment group (no. 25) received 12days a sponge containing 60mg MPA and 500IU eCG on the day of sponge removal. The control group (no. 25) received 12days of sponge containing MPA only. Rams were introduced to the flock after removal of sponges in treatment group and concomitant in control group. They remained within the flock for 40days. The ram to ewe ratio was 1 to 6. Transabdominal ultrasonography was performed for pregnancy diagnosis. The obtained data was analyzed using SPSS software version 16. The conception rate in treatment and control groups were differed significantly (P < 0.01). The conception rates in MPA and MPA+ eCG were 28% and 44%, respectively. Ewes (60%) with < 2years old had the most conception rate. However, it was shown that use of vaginal sponges containing MPA and eCG in removal time of sponge can increase significantly the conception rate in out of breeding season fat-tail ewes Shaal breed.