Analysis of growth curves of indigenous male Venda and Naked Neck chickens
The objective of this work was to estimate and compare the growth curve parameters for live weight of indigenous Venda and Naked Neck chickens and carry out some analyses to test the existence of differences in the growth pattern between these breeds. The data were collected from the two breeds of chickens that were reared from day-old to 21 weeks of age. Two hundred chickens (100 of each breed) were used. Three different non-linear models, namely Gompertz, Logistic and Richards, were used to define the growth curves of the chickens. Models were compared using Coefficients of determination (R2 values), A parameter values, the Durbin-Watson Statistic (DW) test for autocorrelation, computing difficulty based on the number of iterations needed for convergence and size of residual variances. The R2 were high for all models: 0.996, 0.990 and 0.997 for Gompertz, Logistic and Richards, respectively. Residual variances were 2240, 5924 and 1154 for Gompertz, Logistic and Richards, respectively. The Gompertz model was observed to be suitable for explaining the growth of the chickens. Breed differences were observed in the growth parameters of chickens. The Venda breed was observed to be late maturing and heavier at maturity while the Naked Neck was shown to have a higher growth rate, reaching maturity earlier but attaining a lighter mature weight.
Keywords: Growth parameters, growth models, breed differences
South African Journal of Animal Science Vol. 37 (1) 2007: pp. 21-26