Comparison of cervical, transcervical and laparoscopic insemination of ewes with chilled stored and frozen ram semen

J.F. Smith, J. Parr, S. Beaumont, J.E. Oliver, G.C. Upreti

AgResearch, Dairy and Beef Division, Ruakura Research Centre, Private Bag 3123, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1995, 55: 248-250

Romney ewes (365) were treated in February for 14 days with CIDR’ devices and inseminated (50-56 h) after device removal. Semen was diluted in a milk based diluent to concentrations of 800 x 10 6/ml for cervical insemination (CAI) (0.2 ml) and 200 x 10 6/ml for TAI and LAI (0.25 ml straws) and cooled to 15 C until insemination either 12-18 hr (D 0) or 36-42 hr (D 1) after collection. Frozen semen (100 x 10 6 sperm; >50% motile, in 0.25 ml straws) from the same rams was used via the TAI and LAI methods. All inseminations were on a time basis about 52 h after CIDR removal. Oestrous status of ewes at AI and the depth of TAI were recorded. Pregnancy was determined by ultrasonic scanning 50 days post insemination. Two additional trials were conducted in Nov-Dec (214 ewes) and March (115 ewes) in which TAI and LAI were compared using D 0 semen.

In the main trial LAI (63%) was superior to TAI (40%) (P<0.05) while CAI (50%) was intermediate.

Within the TAI method full penetration of the cervix (achieved in 51% of the ewes) had higher conception results than partial penetration (52% vs 30%, P<0.05). The full penetration rates with chilled semen were no better than CAI while partial penetration was lower (P<0.05). Oestrous status at time of AI influenced the results with conception rates of oestrous ewes being higher (60.7% v 39.7%; P<0.001). TAI penetration rate was not influenced by oestrous status. Results from the two additional trials support those from the main trial in relation to chilled semen. With frozen semen there were no significant differences between TAI or LAI (64.1 vs 66.7) nor between levels of penetration with TAI (full 68%, partial 58%).

Under the conditions of these experiments TAI did not prove to be a suitable alternative for LAI. The poor results of partial TAI compared to CAI with chilled semen probably reflects the difference in sperm numbers per inseminate used with the two methods and suggests that success of the TAI technique may be concentration dependent. This is supported by the data with the frozen semen. However this data (frozen semen) is at variance with previous published information on the TAI technique.

Keywords: NZSAPAB; ram semen; insemination techniques; transcervical (Guelph); pregnancy rate