Duration effect of fresh semen kept in vitro on sheep conception rate

Yearling Akkaraman ewes (n = 140) were apportioned into two groups and inseminated with fresh semen collected from Suffolk and Dorper rams. Bilateral intrauterine insemination (100 x 106 spermatozoa in 0.25 ml) was performed with the aid of laparoscope. Fixed time insemination was carried out 48-50 h after controlled intravaginal drug release (CIDR) removal with the aid of estrus detection using vasectomized rams. Uterine tone at the time of insemination was scored (1-3), the highest pregnancy rate achieved for ewes with score 3 (67%), followed by 59 and 47% for scores 2 and 1, respectively. General decrease in pregnancy rates were observed with increased duration of stored fresh semen over the insemination period (Fall from 73 to 57% over 120 min storage). However, a slight increase in conception rate was observed at the time of AI with the semen kept in vitro for a longer period (90-120 m) which might be the most appropriate time relative to ovulation.