Modelling growth patterns of three guinea fowl varieties using non-linear models

Growth as an essential economic trait can be evaluated using mathematical growth models. Knowledge of growth patterns is crucial for improving management, nutrition practices, and breeding programs to maximize profit in the poultry industry. This study aimed to evaluate the growth patterns of three varieties of guinea fowl, including pearl, lavender, and white, using non-linear models. For this purpose, the body weights of 291 guinea fowl keets (129 pearl, 108 lavender, and 54 white) that were individually recorded from hatch to 168 days of age, were used. Five non-linear models (Gompertz, Logistic, Richards, Lopez, and Weibull) were fitted on the body weight of varieties, and goodness of fit was compared among the models by the mean square error (MSE), Akaike information criterion (AIC), Bayesian information criterion (BIC), and adjusted coefficient of determination (R_Adj²). Additionally, the correlation between observed and predicted values (r) was used to determine the accuracy and predictive ability of the models. Using the model parameters, additional parameters such as age and weight at the inflection point, as well as the absolute growth rate at various ages, were calculated and compared across the different varieties. Based on the goodness of fit criteria, the Lopez and Logistic models were the best and worst models to describe the growth pattern of the three varieties compared to other models, respectively. Most model parameters showed significant differences among the three varieties. The white variety (46.975 d) had a significantly lower age at the inflection point compared to the other two varieties (47.361 and 48.169 d for lavender and pearl varieties using the Lopez model, respectively). Additionally, the weight at the inflection point for this variety was 431.946 g, which was higher than the lavender (415.405 g) and pearl (408.698 g) varieties. Considering the growth parameters of the three varieties, the white variety can be recommended for raising as broiler poultry compared to the other two varieties.