Abstract

In each of 2 years Coopworth ewes were randomised to 8 groups which were offered 2 levels of herbage allowance (1.0 and 5.0 kg DM/ewe/d) from mixed pasture for varying periods during the 6 weeks prior to a synchronised mating. The ovulation rates of ewes fed at the lower allowance and then given the higher allowance for periods of 1 or 2 weeks prior to mating were not different from those fed continuously at the lower allowance. Ewes offered 3 weeks at the higher allowance showed a 25% increase in ovulation rate irrespective of when in the 6 week period this was received. Thus a minimum carry over period of 3 weeks was obtained. A further 30% increase in ovulation rate was obtained when ewes were offered the higher allowance for the full 6 week period. The proportion in ovulation rate was obtained when ewes were offered the higher allowance for the full 6 week period. The proportion of ewes lambing multiples was lower for those receiving <3 weeks high level feeding than for those receiving at least 3 weeks (33.5% v 56.0%; P<0.001), but there was no additional response to feeding at the high level for 6 weeks.

PF, Fennessy

Proceedings of the New Zealand Society of Animal Production, Volume 43, , 1-6, 1983