No abstract

The aim of the study was to evaluate the productivity and efficiency of ewes, relative to the body weight and metabolic body weight in four hair sheep breeds. The dataset included the records of litter size, parity number, birth weight, weaning weight, age at weaning, and ewe body weight (EBW), recorded 24 hours after lambing, from 926 purebred ewes. In total, there were 1,198 lambing records (114, 86, 434 and 564 for Blackbelly, Dorper, Katahdin and Pelibuey, respectively). Ewe metabolic body weight at lambing was calculated as EBW0.75. Ewe productivity was evaluated at weaning, and ewe efficiency as the ratio of kg of lamb produced at weaning (adjusted at 60 d of age) divided by ewe body weight or EBW0.75, respectively. Katahdin and Dorper ewes had greater body and EBW0.75 compared to Blackbelly and Pelibuey ewes (P<0.05). There was no difference for those traits between Blackbelly and Pelibuey ewes (P>0.05). Katahdin weaned heavier litters than the other breeds (P<0.05); however, there were no differences between breeds for ewe efficiency at weaning (P>0.05). Third parity ewes were more efficient than both early and late parity ewes (P<0.05). Lambing season was a significant source of variation for ewe efficiency (P<0.05). Under the conditions of this study, ewe efficiency could be increased by weaning more than one lamb.