Analysis of production records from a lowland sheep flock 2. Flock statistics and reproductive performance

Abstract

SUMMARYThe reproductive performance of a lowland flock of Clun Forest ewes is reported. During the period from 1955 to 1966, over 1300 ewes entered the flock and more than 4800 lambing records were obtained. The effects of culling and death on the records available were investigated and it was found that the reduction of the material caused by death was random, while that caused by culling was related to previous performance.Barrenness decreased with age, and for ewes aged 1, 2 and more than 2 years was 44, 7 and 5%. Average litter sizes (ALS) over the same ages were 1·15, 1·55 and 1·75. Accordingly the number of lambs born per ewe mated and present at lambing also increased with age of ewe, and values for the same ages were 0·64, 1·44 and 1·68.An analysis of over 170 ram mating groups, consisting of ewes older than 1 year, revealed no differences between rams on the ALS of their mates. The results of a similar smaller analysis of barrenness among 1-year-old ewes also showed no evidence of a ram effect.