Growth of genotypes of an alternative strain of broiler chickens

The aim of this work was to compare the growth pattern, adjusting the growth curves by nonlinear models and studying the development of housing sections in relation to the weight of the chicken carcass in different genotypes of an alternative strain of broiler chickens. We used 840 one day old male chicks distributed in a completely randomized design, with the following genotype strains: Redbro: Caboclo, Carijo, Colorpak, Gigante Negro, Pesadao Vermelho, Pescoco Pelado and Tricolor. The birds were housed in 28 boxes, 30 birds / box in a masonry shed with access to a 45 square meter paddock, with four replications. Body weight was measured in chickens up to 84 days of age. To determine the growth curves of the body weight of birds, collected data were evaluated from the nonlinear models: Brody, Gompertz, Logistic, Richards and von Bertalanffy. Was used "proc nlin" of SAS, using the iterative method of Gauss-Newton. The criteria used to choose the best model for the growth curve were the coefficient of determination, the asymptotic standard deviation, the mean absolute deviation of the waste and the asymptotic index. The analysis to obtain the allometric coefficients were performed using the "proc glm" SAS for genotypes Carijo, Colorpak, Pesadao Vermelho, Pescoco Pelado and Tricolor. We assessed the weights of carcass, breast, thighs, drumsticks, legs and wings. Only the equations proposed by Gompertz, Logistic and von Bertalanfy reached convergence, and the model proposed by von Bertalanffy was the most appropriate. All sections were evaluated in relation to the late growth of carcass weight in alternative lines of broiler chickens.