body weight

broilers

growth curve

Fabens

Gompertz

von Bertalanffy

Growth in broilers has been largely described in the literature by the Gompertz equation. In the present study, the von Bertalanffy equation is evaluated with regard to its ability to describe the relationship between body weight and age in chickens, and is compared with its limiting cases: the Gompertz and the Fabens equations. A total of 60 time course profiles with broilers (male and female) and with meat and egg strain pullets and hens taken from the literature were used in the analysis. A comparative analysis was carried out based on model behaviour, biologically meaningful parameter estimates and statistical performance. The results of this study based on residual sums of squares values confirm the initial assumption of the possible limitation of the Gompertz equation with its fixed point of inflexion at 1/e (= 0.368) times the final weight. This was especially true for female data profiles. For these data profiles, the point of inflexion of the von Bertalanffy equation, which gave a better fit to the data than the Gompertz and Fabens equations, occurred at 0.296 to 0.357 of the final weights.