Estimates of genetic parameters and heterosis for birth weight, one-month weight and litter size at birth in five goat breeds

Abstract

Records of birth weight, one-month old weight and litter size at birth, from 19,887 kids were collected from 1979 to 2000 at the National Goat Centre of Tlahualilo, located in northern Mexico. Local goats of a non-defined breed were recurrently crossed with imported sires of Granadina, Nubian, Alpine, Saanen and Toggenburg breeds. After editing, the data comprised of 12,641 kids and a pedigree file of 14,762 animals. Estimates of (co)variance components, heritability and repeatability of the aforementioned traits were obtained using a mixed model that included the fixed effects of sex, litter size, age of the dam at kidding, season-year of kidding, breed group, level of upgrading of the dam and the interaction between the breed of dam and breed of sire, as well as direct genetic, maternal genetic and maternal permanent environment random effects. The Granadina kids had the lowest birth and one-month weights. Estimates of direct heritability of the five breeds ranged from 0.202 to 0.510, 0.036 to 0.414 and 0.034 to 0.154 for birth weight, weight at one month of age and litter size, respectively, with several estimates for LS being non estimable. Maternal heritabilities ranged from 0.154 to 0.278 for birth weight and 0.023 to 0.378 for weight at one month of age. Only two estimates of maternal heritability were estimated for litter size and both were not significantly different from zero. Correlations between direct and maternal genetic effects were all negative for birth weight and litter size. Genetic and maternal correlations among all traits, estimated in the overall multi-breed population, were not significantly different from zero. These estimates are generally within the range of values reported for other breeds. A negative heterosis was found for both weight traits in the case of Granadina sires. Our estimates for birth weight and litter size are higher than the values reported in other studies with meat breeds.