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• Modeling Growth Curves to Estimate the Suitable Slaughter Ages for Tien Yen Female Chickens Raised by Different Diets

  Ha Xuan Bo, Nguyen Van Duy, Nguyen Thi Nga, Bui Thi Kim Oanh, Vu Dinh Ton

  Received: Mar 28, 2025 / Accepted: Aug 25, 2025 / Published: Sep 30, 2025

   Abstract PDF

  This study aimed to find the best model to describe the growth of Tien Yen female chickens and predict their live weight, weight gain, and suitable slaughter age. The body weights of 180 female chickens were measured every week from birth to 24 weeks of age. The chickens of the control group were fed a diet lower in protein and fiber. The chickens of the treatment group were fed a diet higher in protein and fiber. The data for growth performance were analyzed in R using six mathematical functions (von Bertalanffy, Janoschek, Gompertz, Logistic, Lopez, and Richards). The best models to describe the growth of Tien Yen females were Janoschek for the control group and Richards for the treatment group. The maximum absolute weekly gains occurred at 10 and 11 weeks of age (at the reflection point of the growth curves) and the maximum average weekly gains were obtained at 13.39 and 14.62 weeks of age for the control group and treatment group, respectively. Under the current local market conditions, the estimated economically optimal slaughter ages were 14.33 weeks (1,392.89g) for the control group and 15.17 weeks (1,565.23g) for the treatment group.

• Application of Mathematical Models to Predict Growth and Optimum Slaughter Ages of Na Tau Ducks in Vietnam

  Tran Bich Phuong, Ha Xuan Bo, Bui Huy Doanh, Nguyen Thi Phuong Giang, Nguyen Hoang Thinh, Do Duc Luc, Pham Kim Dang, Nguyen Thi Vinh

  Received: Mar 29, 2025 / Accepted: Aug 30, 2025 / Published: Sep 30, 2025

   Abstract PDF

  This study was aimed to analyze the growth curves and predict the optimum slaughter ages of Na Tau ducks. Six mathematical models, namely von Bertalanffy, Janoschek, Gompertz, Logistic, Lopez, and Richards, were employed. Body weight data were collected weekly from birth to 10 weeks of age. The parameters used to evaluate the growth functions were the coefficient of determination (R2), the AIC (Akaike's information criterion), BIC (Bayesian information criterion), and the standard error of the regression function (SER), as analyzed using R software. Among the models tested, the Janoschek model provided the best fit for both male and female ducks, as it exhibited the lowest AIC, BIC, and SER values, together with the highest R2. The asymptotic body weights of male ducks ranged from 2213.16g (Logistic model) to 2726.58g (Lopez model), whereas for female ducks, they were estimated between 1968.89g (Logistic model) and 2401.25g (Lopez model). The maximum average weekly gains (AWGmax) estimated by the best-fit model were recorded at 6.28 and 5.81 weeks for males and females, respectively. Based on these findings, the optimal slaughter ages were determined to be 6.28 weeks for male Na Tau ducks (with a body weight of 1617.34g) and 5.81 weeks for females (with a body weight of 1410.9g).