Fitting and analysis of growth curve of Anyi gray chicken

Objective This study aims to fit the growth curve of Anyi gray chickens using nonlinear models to investigate their growth patterns and provide a theoretical basis for production. Method A total of 100 fertilized eggs were collected from the Anyi Gray Chicken breeding farm，and 91 chicks were hatched.The chickens were reared in mixed-sex multilayer cages from 0 to 6 weeks and in free-range groups under woodland from 7 to 18 weeks.Body weights were measured at 0，2，4，6，8，10，12，14，16，and 18 weeks of age.Three nonlinear models Logistic，Von Bertalanffy，and Gompertz were applied to fit the growth curves of male and female Anyi gray chickens. Result All three models achieved R² values above 0.99.The Von Bertalanffy model showed the best fit for males，while the Gompertz model was optimal for females，both with R² values of 0.998.The inflection point of the body weights for male and female chickens were 782.89 g and 469.39 g，respectively，and the inflection point of ages were 9.21 weeks and 7.51 weeks，respectively.The weight of cocks in this breed was significantly（PConclusion The Von Bertalanffy model is identified as the most suitable for male Anyi gray chickens，with the equation：W=2 642.25×（1-0.807e-0.096t ）3.The Gompertz model is optimal for females，with the equation：W=1 275.95e-3.747×exp（-0.176t）.