Effect of birth rank and age at first lambing on lifetime performance and ewe efficiency

Abstract

Composite ewes (244 single, 258 twin and 255 triplet born) lambed first either as a one or two-year-old. One-year-old lambing resulted in lighter ewes at both 2nd and 3rd mating. Twin and triplet born ewes were lighter than single born ewes throughout their life. Ewe losses due to lambing as a one-year-old meant fewer ewes left to lamb in later years. This meant that after the two-year-old lambing the ewes that first lambed as a two-year-old weaned more lambs per original ewe than ewes that had lambed previously. This difference got smaller over time and the extra lambing meant the ewes that first lambed as a hogget produced more weaned lambs in total (6.7 vs. 5.9 lambs, P < 0.05). Lifetime weaning weight per original ewe did not differ with ewe birth rank groups but the triplet and twin born ewes were smaller than single born ewes. Thus, mating ewes to lamb as a hogget produced an advantage in the amount of lamb weaning weight produced over a ewe’s lifetime but other than frame size, there was no effect of the ewes own birth rank on lamb production.