Narushin-Takma models as flexible alternatives for describing economic traits in broiler breeder flocks

Three Narushin-Takma (NT) models (NT1, NT2, and NT3) were examined for their ability to describe different curves obtained from broiler breeder flocks. The models NT1, NT2, and NT3 comprise 3 flexible mathematical functions (rational polynomial functions) with 5, 6, and 7 parameters, respectively. The characteristics fitted were BW, egg production, egg mass, egg weight, first- and second-grade eggs, hatchability, feed intake, and feed conversion ratio. To evaluate the ability of these NT models to fit the different curves, comparisons were made with more commonly fitted functions (Gompertz, modified compartmental, Richards, Adams-Bell, and Lokhorst). Comparisons revealed a higher accuracy of fit with the NT models, proving their general flexibility. This study likely represents the first time a generic model has been demonstrated to fit all these characteristics satisfactorily. Results showed that in most cases, NT3, because of its greater number of parameters, gave the highest accuracy of prediction. The NT models are likely to fit most curves and are therefore advocated for accurate prediction of other traits with a minimum of mathematical complexity.