Comparison of nonlinear models for predicting live weight growth curves in lamb production of Kıvırcık and Karacabey merino

Abstract

To achieve sustainable lamb production, it is crucial to determine the optimal slaughter age for maximum economic efficiency and have a comprehensive understanding of breed characteristics. This study focuses on evaluating different nonlinear models to determine the optimal slaughter age for Karacabey Merino and Kivircik lambs, renowned for their early development and superior meat quality, respectively. The dataset comprised age -related live weight data from 98 lambs, including 36 female and 15 male Kivircik lambs, as well as 33 female and 14 male Karacabey Merino lambs. Six models, namely, negative exponential, Brody, Gompertz, logistic, Bertalanffy, and Richards were utilized to analyze the data. The model parameters were estimated through an iterative process, and their goodness of fit was evaluated using various metrics. The adjusted coefficient of determination for male Kivircik lambs was 0.9755, while female Kivircik lambs exhibited a lower value of 0.8912. For Karacabey Merino lambs, males had an adjusted coefficient of determination of 0.9534, while females had a slightly lower value of 0.9044. The study concluded that the Brody model provided more accurate predictions for the growth curve of these sheep breeds compared to the other models.