Response of ewes to lupin supplementation at different times of the breeding season

Abstract

Groups of 100 ewes grazing natural pasture in southern Western Australia were fed supplements of 750 g lupin grain for nine consecutive days every six weeks from October 1975-March 1976 to test whether the consistently low ovulation rate in West Australian sheep would vary with season if nutrition were better than normal. The ovulation rate of unsupplemented control ewes was from 1.05- 1.13 and did not vary significantly with season. Ewes responded significantly to supplementation and this response was unrelated to changes in body weight and varied in magnitude with season. It was about 20% in October, January and March but not significant in December. It is concluded that ovulation rates in pasture-fed sheep in the Mediterranean environment of southern Western Australia can vary with season, but only when the sheep are supplemented.