The application of exponential method in the analysis of growth curve for Japanese quail

This study was carried out to estimate the parameters of Gompertz and Logistic growth curve models by using the modified exponential and Marquardt methods in an unselected Japanese quail population. Body weights were collected on one hundred and twenty eight quails each week until 15 weeks of age. There was not any significant difference between both methods to estimate the parameter of mature weight within each model. However, the estimates of P and K by the applied procedures differed. The results also showed that there was significant sex effect on parameter estimates. The methods of Marquardt and modified exponential provided very high Pearson correlation coefficients (0.99) between observed and predicted body weights for Logistic and Gompertz models. The Logistic model was found to provide a better fit for females and overall evaluation; however, the Gompertz model was the best one for males to predict growth curves.