Age and breed effect of ram on ewe's reproductive performance
T.S. Ch'ang, R. Evans
CSIRO, Division of Animal Production Blacktown, NSW 2148,
Australia
Proceedings of the New Zealand Society of Animal Production.
1979, 39: 77-86
An experiment of factorial design, involving 1051 ewes and 30
rams of 3 different breeds (Dorset Horn, Merino, Corriedale), was
conducted under grazing conditions in Armidale, NSW, Australia, to study
the effect due to age of ram (1½- versus 2½-year-old) on ewe's
performance during mating and ensuing lambing. In the Dorset Horn ram
breeds, the use of 1½-year-old rams resulted in lower rates of
conception in the mated ewes compared with those mated to 2½-year-old
rams. This age-of-ram effect did not occur in the Corriedale ram breed.
In the Merino ram breed some evidence of an age-of-ram effect was found
but the differences in lambing performance were not statistically
significant. No evidence was found that occurrence of the age-of-ram
effect, such as that observed in the Dorset Horn ram breed, had biased
the estimate of maternal heterosis of the ewe's reproductive rate.
Implications of these findings for sheep breeding practices are
discussed.
Keywords: NZSAPAB;
Last Updated 12-09-1998
