Genetic evaluation for growth traits in Mexican Pelibuey sheep

The objective of this study was to estimate genetic parameters for weight traits for the Pelibuey sheep. The traits analysed were birth weight (BWT), weaning weight (WWT), weight at 120 d (W120), weight at 150 d (W150), and weight at 210 d (W210). Data set with records from 51,382 lambs, progeny of 1,440 sires, and 14,715 dams were used to conduct genetic analyses, using an animal model. Six models varying the random effects were fitted including genetic, maternal and maternal permanent environmental effects. Then, the same base models were fitted with the additional random effect of sire by flock interaction. Direct heritability estimates for the base models ranged from 0.13 to 0.18 and reduced across all traits when the sire by flock was fitted in the model (0.03 to 0.11). Additive genetic correlations ranged from 0.49 to 0.96 and 0.81 to 1.00 for the base models and sire by flock models, respectively. Validation analyses were performed to study the predictability of sire EBVs on progeny performance, with a cross-validation procedure developed for W120. Fitting sire by flock improved predictability, with values for all sires at 0.22, and for link sires at 0.43, close to the expected value of 0.50. The estimated annual genetic trends were 0.011, 0.051, 0.060, 0.068 and 0.045 kg/yr for BWT, WWT, W120, W150 and W210, respectively, for the period between 2010 and 2017. Overall, the results indicate that an across-flock genetic evaluation for Pelibuey sheep in Mexico is possible.