The objective of the present study was to evaluate non-linear models to describe Morada Nova sheep herds raised in the State of Bahia and, after defining the best suiting model, calculate the rate of absolute growth and evaluate the influence of environmental factors (sex and type of parturition) on the curve parameters. Weighting data from 40 sheep from birth up to 385 days of age were used. The non-linear models used were: Brody, Von Bertalanffy, Richards, Logistic and Gompertz. Von Bertalanffy, Brody and Richards models presented the best adjustments and were equivalent to explain the growth of the analyzed animals. A remarkable drop in the absolute growth rate was observed after weaning, suggesting that a proper diet should be implemented to supply the nutritional demands of the animals at this stage. The environmental effects (sex and type of parturition) have significantly influenced the maturity rate (k), but only the sex of the lamb affected weight at maturity (A). Animals born from single parturition proved to be heavier than twins which, in turn, presented compensatory gain. The growth of males was higher than of females and the latter presented more precocity than males. Estimated correlation between parameters A and k was negative (-0.65) for the Von Bertalanffy model and for the Brody and Richards models (-0.71) indicating that the most precocious animals are less likely to reach elevated weights when adults.
environmental effect; non-linear models; weight at maturity
