Linear and nonlinear mixed model analyses of growth performance of commercial U.S. dairy buck kids

Abstract

The objectives of this research were: (1) to describe the growth of crossbred, intact, dairy buck kids from shortly after weaning to slaughter weight and (2) to determine whether raising them can be profitable. The kids in this study were purchased from three commercial dairy goat farms and were fed to slaughter weight in two separate environments. Individual kid body weight (BW) and pen feed disappearance was recorded. Both a linear mixed model and a nonlinear Gompertz mixed model were implemented to describe BW over the time of the feeding trial. The fits of the models were compared by −2 log likelihood, Akaike information criterion, and Bayesian information criterion. All fit statistics favored the nonlinear model, though upon visual inspection, growth was near linear. Although groups of kids were sold at varying weights and for different prices, revenues over kid purchase price and feed costs were positive. Feeding cull dairy kids can be profitable under many production scenarios.