Plasma FSH, LH, prolactin and progesterone profiles in Cheviot ewes on high and low intakes prior to mating

Extract

Ovulation rate and lambing rate of Cheviot ewes are improved by both increased body condition and premating food intake. The aim of this work was to investigate the endocrine mechanisms by which one of these factors, intake, could influence reproductive performance.

Two similar groups of 20 ewes were fed differentially to achieve condition scores of either 2.0 or 2.5 by 4 weeks before mating in November. Low condition animals were then fed ad libitum and achieved a mean condition score of 2.3 and mean liveweight of 58 kg at mating. The remainder were offered a maintenance ration and had a mean condition score of 2.5 and mean liveweight of 55 kg at mating. Blood samples were collected at 20 minute intervals for 10 h approximately 7 days before mating and for 5 h on each of the 3 days immediately prior to the anticipated day of oestrus.