Prediction of lifetime reproductive performance of Australian Merino ewes from reproductive performance in early life

Abstract

The lifetime reproductive performances (5 annual cycles) of 2105 Merino ewes from a multiple bloodline flock (15 separate bloodlines) were used to determine the association between reproductive performance in early life (either at 2 or 3 years of age, or the combined information from both years) and later performance. Early life fertility was indicative of both the fertility and the rearing ability of ewes in later life. The relationship of the combined weaning performance at the first and second annual reproductive cycles with reproductive performance in later life suggested gains were possible in the current flock from culling with emphasis on low fertility and rearing ability. Ewes that were dry at 2 and 3 years of age subsequently reared only half as many lambs as ewes that had reared lambs at 2 and 3 years of age.