Observations on the sexual activity of Border Leicester × Merino ewes in late winter, spring, and summer

Abstract

A group of 160 five-year-old Border Leicester x Merino ewes were joined to harnessed vasectomized rams in August 1962. Between this date and January 1963 inclusive, ten of these ewes were slaughtered each fortnight and their ovaries examined for occurrence of ovulation. Occurrence of mating was also recorded up to the end of March 1963. The number of slaughtered ewes in anoestrus gradually increased during August-September. All ewes slaughtered between September 26 and December 19 inclusive were in anoestrus. The number of ewes in anoestrus decreased in January when the sexual season began to recommence.