Ovulation and oestrous responses of high and low fecundity ewes
to ingestion of isoflavone-rich pasture
R.W. Kelly, G.H. Shackell
Invermay Agricultural Research Centre, Mosgiel
Proceedings of the New Zealand Society of Animal Production.
1982, 42: 29-32
Groups of high and low fecundity Booroola x Romney (B x R) and
Romney (R) two-tooth ewes grazed a pasture containing 85% 'Grasslands
Pawera' red clover for 10 days; similar groups of ewes grazed ryegrass-
white clover control pastures. Oestrus and ovulation were synchronised
in all ewes to occur during the last 5 days of grazing. Pawera leaf
material contained 0.7% formononetin and the pasture was highly
oestrogenic to sheep (>40 µg oestradiol - 17 ß). Mean ovulation rates
in the B x R-High, B x R-Low and R ewes were consistently but not
significantly, lower in the flocks grazing Pawera than control pastures
(2.08 v 2.69, 1.08 v 1.30, 1.09 v 1.40, respectively). The mean
ovulation rate of the ewes grazing Pawera was lower (P<0.05) at the time
of grazing the pastures than 1 month later at joining. There were no
significant effects of pasture treatment on proportion of ewes ovulating
or marked by vasectomised rams. There was no evidence that fecundity
status influenced the responsiveness of ewes to isoflavone-rich pasture.
Keywords: NZSAPAB;
Download abstract in text format
Last Updated 03-05-1997
