The influence of nutrition on reproduction in the ewe 1. Effects on ovulation rate, follicle development and luteinizing hormone release

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Abstract
Two groups of 15 ewes in store body condition were either given a maintenance level of feeding or a twice-maintenance level (flushed) during the course of one oestrous cycle. Five ewes from each feeding level were slaughtered at 0, 18 or 48 h after the onset of the oestrus at the end of the treatment period and measurements were made of the luteinizing hormone content of their pituitary, the luteinizing hormone concentration in their blood plasma, their ovulation rates, and ovarian follicle numbers and sizes.‘Flushed’ ewes had a significantly higher ovulation rate (260, s.e. 0·24 v. 1·80, s.e. 0·20; P <0·05), although there was no significant difference in either pituitary luteinizing hormone content or plasma luteinizing hormone concentrations at oestrus.Analysis of the patterns of ovarian follicle distribution suggest that flushing ewes for one oestrous cycle might increase ovulation rate by preventing the late atresia of large follicles in the last 30 h before ovulation.