Effect of Body Weight of Ewes on Subsequent Lamb Production

Abstract

Birth and weaning weight records of 962 and 805 spring-born lambs, respectively, were analyzed. Age of dam did not significantly affect weight of the lambs at birth, but the 2- and 7-year-old ewes tended to wean lighter lambs. Sex and type of birth of the lambs exerted the most pronounced effect of the factors studied. Twin lambs weighed 0.76 and 7.1 kg. less than single lambs at birth and weaning, respectively. Twin ram lambs were 0.59 and 1.8 kg. heavier at birth and weaning than twin ewe lambs. There was a 5.63-kg. increase in weaning weight with each kilogram increase in birth weight. The greatest response of weaning weight to increase in birth weight occurred in the single lambs. The body weight of the ewes markedly affected weaning weight and to a lesser degree the birth weight of lambs. As the body weight of ewes increased, there was a significant increase in weaning weights of lambs. The heaviest ewes (59.5 to 63.6 kg.) produced heavier lambs at birth and at weaning than did other ewes in this study. An increase in the ewes' body weight of 1 kg. resulted in a 0.1-kg. increase in weaning weight of lambs.