Relationship between semen traits, mating frequency and percentage of ewes lambing multiples in high fertility Romney sheep

R.W. Moore and D. Whyman

Whatawhata Hill Country Research Station, MAF, Hamilton

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Proceedings of the New Zealand Society of Animal Production. 1977, 37: 137-141

Semen from 10 rams singly mated to 50-80 ewes in the Waihora Selection Project in 1973, and 16 rams similarly mated in 1975, was subsequently collected. Two semen traits, percentage normal sperm and wave motion score, were significantly correlated with the percentage of ewes lambing multiples (% ELM/EL), the pooled correlations being 0.64 (P<0.01) and 0.42 (P<0.05), respectively.

Fifteen rams singly mated in 1973 were each assessed for serving frequency during a total of eight 1-hour sessions with 5 oestrous ewes in a pen. Tests were carried out during May-June and November-December. The mean number of serves per hour during the two periods was 6.5 and 2.8 respectively, indicating a seasonal effect (P<0.001). The correlation between the mean pen mating frequency and % ELM/EL was not significant (r=0.18).

Twenty rams were observed at the 1975 Waihora mating during morning, midday and afternoon periods. The mean number of serves per hour was 1.1, 1.2 and 1.8, respectively, indicating a diurnal rhthym in serving frequency (P<0.05). The mean mating frequency was not significantly correlated with % ELM/EL (r=0.10). Sixteen of these rams were subsequently tested for serving frequency in pens and small paddocks. Neither of these tests gave a significant correlation with mating frequency at the Waihora mating nor with % ELM/EL.

Keywords: NZSAPAB;

Last Updated 24-08-2000