Abstract:

【Objective】 The aim of the study is to describe and estimate the trajectory and parameters of body weight growth of native Muscovy. 【Method】 One hundred and sixteen Muscovy ducks were fed and observed for 21 weeks, five body weight growth functions including Gompertz, Logistic, Von Bertalanffy, Richards, and Brody were estimated, nonlinear mixed effect models were fitted to data of body weight in Muscovy, and the 8 growth parameters including mature weight, Point of inflection (POI), POI weight, birth weight, absolute growth rate, relative growth rate, absolute maturing rate, and relative maturing rate were computed for these models in this study. The results of fitting and estimating with these different growth models were compared using information criteria,error variance, and accuracy of estimated growth parameters for evaluating the alternative models. 【Result】 The 5 nonlinear mixed effect models with 8 growth parameters each were fit for body weight of Muscovy ducks. Their accuracies had a much larger increase than these of the nonlinear fixed effect models. Among the 5 nonlinear mixed effect models for the body growth of female and male Muscovy, information criteria of Gompertz growth model were least, and reduction of residual error variance of this model was up to 99.92%. For the body growth of male or female Muscovy, information criteria of Richards growth model was least among the 5 nonlinear mixed effect models. Reduction of residual error variance of this model was up to 89.80% for male group, 91.81% for female group. 【Conclusion】 Gompertz,Richards nonlinear mixed effect models are best growth models for fitting the body growth of Muscovy,for male or female Muscovy, respectively.

Key words: nonlinear mixed effect model, body growth, muscovy duck, evaluation