Comparison of non-linear models for describing growth of Guzerat beef cattle females

Data on growth and reproduction of 573 females Guzerat beef cattle born bet ween 1961 and 1985, at Fazenda Canoas, located in the county of Curvelo, MG , Brazil, were used to obtain a growth pattern for the breed, through the u se of a mathematical model. Weight-age data, collected up to 1992, were use d to fit five nonlinear models: Brody, Bertalanffy, Logistic, Gompertz, and Richard. Estimated assyntotic weight and growth rate were, respectively, f or Brody model 464.49 and 0.046; for Bertalanffy model 453.18 and 0.065; fo r Logistic model 447.05 and 0.085; for Gompertz model 449.89 and 0.075, and for Richards model 458.26 and 0.055. Richards model presented computationa l difficulty to fit the data. Other models showed good fit to the data, and presented little variations on the criteria chosen. Bertalanffy model show ed a better goodness of fit on the set of criteria and was the choice to de scribe the growth patterns of Guzerat cattle.