The seasonality of reproductive performance of Merino sheep in Britain

Abstract
SUMMARY A study has been carried out to determine the length of the breeding season and the feasibility of lambing twice a year in Merino sheep in Britain. Six groups of 18 ewes were exposed to rams at monthly intervals, and twice per year, from April 1969 to June 1970. A well-defined breeding season, from August to January, was found, and its shortness, linked with the inability of the ewes to conceive immediately post partum, prevented lambing twice in the year.