Productivity of Pelibuey and Blackbelly ewes in Mexico under extensive management

Abstract Data of 550 Pelibuey (PB) and 250 Barbados Blackbelly (BB) ewes mated during 1987–1990 were used to determine their productivity and some other economic traits at lambing and weaning. Ewes were grazed on native vegetation and given a grain-based supplement during the dry season (November–May) of each year. A model which included the fixed effects of year of mating, breed and lambing group (a combination of parity and weight of the ewe) was used. Blackbelly were superior to PB ewes in prolificacy (1.67 vs. 1.23 lambs), litter size at weaning (1.21 vs. 1.01 lambs) and litter weight (productivity) at birth (4.17 vs. 3.45 kg) and weaning (12.81 vs. 11.49 kg). However, BB ewes had higher lamb mortality until weaning (23.8 vs. 15.1%). Ewes with lower weights than the mean of their lambing group had lower productivity at lambing (3.39 kg) and weaning (11.14 kg) than ewes with higher weights (4.16 and 14.46 kg, respectively). Pelibuey ewes with lower weights than the mean of their group had fewer multiple births (13.7%) than heavy ewes (27.2%). Blackbelly ewes with weights lower or higher than the mean of their group had 46.1% and 65.5% multiple births, respectively. These results provide useful information for sheep management. However, more studies are required to determine the effect of body condition on performance and reproduction of PB and BB sheep.