Observations on the Breeding Season in Sheep and its Artificial Extension

Abstract

Observations on the normal season were made over several years with a small flock of Suffolk X Border Leicester-Cheviot ewes backcrossed with Suffolk rams. The flock was under grassland management ; rams were kept in the whole year round, the fertile ram being usually replaced in the breeding season by a sterile ochred ram. The lambs were left with the ewes until they had ceased to suck. Two ewes have lambed at a time corresponding to service at the end of July or beginning of August ; but the normal season, on the average, extended from mid-September to mid-March, the extremes being the end of August to early April. Ewes suckling lambs born later than July showed slight delay in onset of the breeding season. After lambing in November the interval to the next heat may be as little as three weeks. If ewes are put to the ram at the beginning of the season, so as to lamb down in early February, about half will come on heat again before the end of the season.