Weights of caprine kids of the local Southern Tunisian population under arid conditions: Impacts during selection process

Abstract

The nature and distribution of quantitative phenotypes represent a basic knowledge for the application of genetic methodologies in domestic animal selection plans. To illustrate the action of non-genetic factors of aridity on the phenotypic distribution of individual growth performance of caprine kids of the local population reared under restrictive and irregular conditions, 945 kids from 285 female goats and 19 male goats, born during the period 1998–2014, were studied by analyzing weight distributions up to 150 days of age. The weight dispersion represented a collective expression of the genotypes of the kids under the study conditions with variations due to both genetic and environmental effects. The assumption of normality was only confirmed at 10 days and 30 days of age when kids were mainly fed under the mother and were not directly dependent on dry land feed resources. In an unfavorable year, the recorded performance followed a particular distribution explained by the fact that performing kids were unable to externalize their superiority. Therefore, the dry land environment reduced the performance of the local goat population. In addition, it limited the expression of some highly productive genotypes. The specificity of the action of the arid environment calls for an in-depth study to adjust the selection methods to the conditions of the restrictive environments and of the adapted genetic groups.