Predicting the growth curve of healthy and ascites Arian broiler chickens using nonlinear models

Articles in Press

Document Type : Research Paper

Authors

1 Department of Animal Sciences, Faculty of Agriculture, Tabriz University, Tabriz, Iran

2 Department of Animal Sciences, Faculty of Agriculture, University if Tabriz,, Tabriz,, Iran

Abstract

This research aimed to identify the best nonlinear mixed model to fit the growth curve of healthy and ascites-affected broiler chickens. Body weight records of 823 chickens from the paternal line B of the commercial Arian strain were used, from birth to 45 days. These chickens (381 males, 442 females) were raised at the University of Tabriz research station, with feeding and rearing conditions following guidelines from the Arian Broiler Line Breeding and Improvement Complex in Babolkanar. Results from parameter estimation with a global random effect for eight nonlinear mixed models indicated that the Mitscherlich model was selected as the best for healthy and ascites-affected males (AIC = 33945, 7012.50), and the log-logistic model was best for healthy and ascites-affected females (AIC = 41061, 1468.30). These two models, each with three parameters (B, A, and K), were examined with random effects considered for each parameter. The lowest AIC and BIC values for the log-logistic model were observed with two random parameters (B, K) at 53985 and 54038, respectively, followed by three random parameters (B, A, and K) at 54069 and 54006, respectively. Overall, the findings suggest that the Mitscherlich model for male chicks (healthy and ascetic) and the log-logistic model for female chicks provide the best fit for growth curves under both healthy and ascetic conditions. These models can be valuable in more precise genetic evaluations.

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Iranian Journal of animal Science

Articles in Press, Accepted Manuscript
Available Online from 26 August 2025

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History

  • Receive Date: 15 May 2025
  • Revise Date: 17 July 2025
  • Accept Date: 20 July 2025

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