Effects of diet and liveweight on ovulation rates in "Romney"
ewes
T.W. Knight
Whatawhata Hill Country Research Centre, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1980, 40: 38-42
Different ewe liveweights (49 kg vs. 39 kg) were generated by
differentially grazing two randomly selected groups of mature Romney
ewes. A maintenance ration of 25% chaffed barley straw, 15% hay and 60%
of either lupin (L diet) or barley (B diet) grain was fed to half of
each group. After 31 to 33 days of feeding, the proportions of
multiple ovulating ewes were higher for those fed the L diet in both
liveweight groups. Injection of 100 µg Cloprostenol on day 8 of the
oestrous cycle indicated that the changes responsible for the ovulatory
responses to be combined effects of high liveweight and lupins occur
before day 8 of the oestrous cycle or during regression of the corpora
lutea. High-liveweight ewes had more large follicles on their ovaries
but there was no effect of diet on the number of large follicles on the
ovaries.
Keywords: NZSAPAB;
Last Updated 12-09-1998
