Cervical artificial insemination in sheep

Abstract

Results are reported from a fresh semen cervical artificial insemination trial in April 1989 at the Lincoln College Research Farm. One hundred and ninety Coopworth ewes were inseminated over 5 days. Semen was collected twice daily from four Dorset Down rams using an artifical vagina (A.V.). Fixed-time insemination versus on-oestrus insemination and 'synchronised on-oestrus' versus 'natural on-oestrus' were compared. 'On-time' ewes (TI) were inseminated at 50-51 hours after CIDR withdrawl. On-oestrus treatments (T2 and T3) were drafted twice daily and inseminated on average 15-22 hours after the onset of oestrus. Oestrus was detected by two vasectomised rams and five testosterone treated wethers, harnessed with crayons. Fifty-seven (97%) T1 ewes were marked within 50 hours after CIDR withdrawal. Submission rates were 100% for T2 and T3 (not including 5 (3%) ewes that lost CIDR's). Sixty-four (97%) T3 ewes were inseminated over three days on their second cycle after synchronisation using CIDR's. Two (1%) ewes lambed to A.I with no significant difference between treatments or across insemination days. The low lambing percentage appears to be due to an error in semen handling post collection/dilution, but results may have been compounded by low dose rates (96-232 x 10⁶ spermatozoa/inseminate) and marginal semen quality (motility) prior to insemination. Seventy-seven (41%) ewes were inseminated intrauterine via the cervix (including the two ewes that lambed to A.I). Ejaculate volume and motility varied significantly between collections and between rams - average ejaculate volume was 0.6 ml (0.2 - 2.0 ml), and average motility was 3+ (range 1-4).