The influence of liveweight on ovulation rate in the ewe

A.J. Allison

Lincoln College, Canterbury

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Proceedings of the New Zealand Society of Animal Production. 1968, 28: 115-119

Aged Romney ewes (187) and Border Leicester X Romney ewes (87) were fed high-plane or low-plane nutrition from December 2 to February 18, after which all were run as one mob. Ewes were laparotomized at first oestrus (mid-March) and slaughtered after second oestrus. The mean liveweight differences between high- and low-plane ewes at February 18, first oestrus and second oestrus were 33 lb, 27 lb and 24 lb, respectively.

The ovulation rate of the high-plane ewes exceeded that of the low-plane ewes by 0.05, 0.07, 0.07, 0.25 for the Romneys at first and second oestrus and for the crossbreds at first and second oestrus, respectively. The weighted means for high-plane and low- plane ewes were 1.52 and 1.42 ovulations per oestrus, respectively. The ovulation rates increased significantly from first oestrus (1.35) to second oestrus (1.60) and were greater in crossbred ewes (1.68) than in Romneys (1.37). The findings are discussed.

Keywords: NZSAPAB;

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