The influence of season on the ovulatory activity of Merino ewes slaughtered at a central abattoir

Abstract

The ovulatory activity in Merino ewes from the central western and north-west plains of New South Wales was measured using material collected at Homebush Abattoir from March to November 1960. There were significant differences in ovulation rate and in the incidence of multiple ovulations between the two areas. The ovulation rate dropped from 1.38 in the autumn to 1.20 in the winter to 1.07 in the spring (P<0.01). This resulted mainly from changes in the percentage incidence of anoestrous ewes: from 1.7 to 5.7 to 21.5 (P<0.05).