Using nonlinear models to describe height growth curves in Pantaneiro horses

Height at withers data mostly from birth to 36 months of age of 26 Pantanei ro horses were used to fit Brody, Richards, Gompertz, Logistic, Weibull and Morgan-Mercer-Flodin nonlinear response functions. Based on measures of av erage curvature and combined mean square error, the Weibull model was chose n. The asymptote of this curve, representing the average height at maturity , was higher for males than females. The maturity index, however, was more elevated for females than males. There was indication of a negative associa tion between the maturity index and height at maturity only for females. Th ese results indicate that females mature earlier. After checking for normal ity and homogeneity of variances within groups (sex) the analysis investiga ted sex differences via t-tests. A significant difference was detected only for height at birth.