Growth curve characteristics in Awassi and Morkaraman sheep, part I: Comparison of nonlinear functions

Body weight-age data from fifty-four Morkaraman and seventy-nine Awassi sheep, from birth to thirty-six months of age, were used to obtain a growth pattern for the breeds, with the use of Brody, logistic, Gompertz, Bertalanffy and Richards non-linear functions. In both breeds, the Brody and Richards models, with equal R-2 as 0.99, were superior to the others. However, Brody was precise on its parameters and easy to interpret than Richards function. As a result of heterogeneity, on the other hand, no curve computed using mean body weights in this study had the ability to uniformly represent every individual (p<0.001). Biological interpretations of the model parameters were discussed.