Artificial insemination in sheep - comparison of storage time, dose rate and insemination technique

T.G. Harvey, D.L. Johnson, R.L. Baker, B.K. Trust and B.C. Thomson

Rotomahana Research Station, R.D.3, Rotorua and Ruakura Animal Research Station, Ministry of Agriculture and Fisheries, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1986, 46: 229-232

Trials undertaken at Rotomahana in 1984 and 1985 examined factors involved in sheep AI and provided a link between Rotomahana and a commercial AI programme. Semen collected and diluted by the New Zealand Dairy Board gave similar conception rates (46%) to semen collected at Rotomahana (42%). Results in 1984 indicated that there was a small but non-significant decrease in conception rate with semen storage time up to 15 hours (5 h 68%, 10 h 61%, 15 h 57%). In 1985 there was a highly significant difference between 5 and 20 h storage (46% v 25%) and this result was consistent over ewe ages and dose rate.

In 1985, 200x10 6 sperm dose was compared to 100x10 6 dose in 3 subtrials. The overall conception rates were 45.7% and 37.5% respectively (P<0.05).

In 1984 diluted semen stored in glass and inseminated using a fine glass pipette gave a higher, but not significant, conception rate than semen stored in mini straws and inseminated using a standard cattle pistollet (66% v 58%). In 1985 all semen was stored in glass and inseminated with either a glass pipette (conception rate of 49.8%) or a cattle pistollet (43.2%). This difference was non-significant, although there was a significant interaction of insemination equipment with dose rate.

A significantly higher conception rate was achieved for cervical (52.8%) than blind insemination (29%) when ewes were inseminated 'on time' in 1985 and this effect was consistent over dose rate.

There was no difference in conception rate when 'on-oestrus' insemination was compared to 'on-time' (63% v 61%). All first-order interactions among the effects of storage time, insemination method and 'on-oestrus' v ' on-time' were non-significant in the 1984 trial.

Keywords: NZSAPAB; Sheep; AI: synchronisation; semen; CIDR; reproduction

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Last Updated 18-03-1997