Reproductive and productive performance of hair sheep in a semi-intensive system in southeastern Mexico

Productivity measured as kilograms of lamb weaned per ewe is a composite trait of economic importance and can be used as selection criterion of maternal breeds. The objective of this study was to estimate the reproductive, preweaning growth and productivity performance of hair breed ewes, and the effect some nongenetic factors influencing them under semi-intensive conditions in southeastern, Mexico. Information of purebreds and crossbred ewes and their lambs was used to develop a composite productivity index. The final mixed model used (except for age at first lambing, AFL), included the fixed effect of breed group, year (Y, 2016-2019) and season of lambing (dry, rainy and wind and rainy), lambing number (1, 2, ... >= 5), litter size (LS, single and double for weaning traits), and the random effects of ewe within breed group and residual error. Except for the AFL, the effect of the breed group and all other non-genetic factors were significant (P < 0.0100). No breed or crossbred was superior for all traits studied, yet Commercial Katahdin (K) excelled the most, despite of its reproductive performance. Traits in the productivity index (litter size at lambing, adjusted litter weaning weight and lambing interval) could not be used as an optimal indicator for the identification of the best breed for crossbreeding. The K showed the best maternal ability, except for lambing interval and AFL, influenced by all non-genetic factors which could be improved by sound flock management.