Abstract: As the black Muscovy for experimental material,the early bodyweight of different sexual black Muscovy from 0 to 10 weeks old were measured,in order to investigate the growth model in this study,three kinds of nonlinear models of Gompertz,Logistic and von Bertalanffy were used to fit the growth curve respectively.The results showed that black Muscovy grew slowly before age of 4 weeks,the growth rate accelerated significantly after age of 4 weeks,and reached the growth peak at age of 6 to 10 weeks.Compared with goodness of fit(R²),the results showed the growth curve could be well fitted with these three models and the R2 was above 0.99,but the Gompertz model had well closed to the actual observed values.Further more,the fitting parameters of Gompertz model between genders were compared,and the male black Muscovy showed higher initial weight,maximum bodyweight,and inflection point weight than female black Muscovy.The inflection age of male was 5.3 weeks and the female was 4.3 weeks.The Gompertz model equation for male and female black muscovy was W=3111.4[exp-4.4482exp(-0.2802t)] and W=2100.4[exp-4.1071exp(-0.3225t)] respectively.This study would help to understand the growth model and development of different sexual black Muscovy,and would provide the scientific basis for rational use of resources,breeding germplasm and selection in black Muscovy.

Key words: Black Muscovy, growth curve, body weight, model