Control of the annual rhythm of breeding in ewes: effect of an equatorial daylength with reversed thermal seasons

Abstract

1. Three groups of seven Southdown and seven medium wool Peppin Merino ewes were subjected, respectively, to seasons of daylength corresponding to a latitude of 60° S., reversed seasonal lighting (60° N.) and an equatorial daylength with reversed thermal seasons, for 2½ years. During the next 20 months group 1 continued as before. Group 2 had a 32-week photoperiodic year and group 3 had a 32-week thermal year with equatorial daylength.