Estimation of body weight growth curve parameters of Katjang-Boer crossbred
2020
Mohamad Hifzan R. | Mohd. Hafiz A. W. | Izuan Bahtiar A. J. | Nurulhuda M. O.
The objective of this study was to determine the best non-linear regression model to describe the growth pattern of male Katjang-Boer crossbred goat, a new synthetic goat breed. Estimates of mature weight (A), rate of maturing (k) and constant of integration (B) as growth curve parameters were derived from four non-linear regression models, namely Brody, Logistic, von Bertalanffy and Gompertz. Monthly body weight data were collected from 66 male Katjang- Boer crossbred from birth to 48-mo of age and fitted with the above non-linear regression models. Coefficient of determination (R²) and residual mean squares (MSE) were used to determine the best non-linear model to estimate the growth curve parameters. Von Bertalanffy model showed the best goodness of fit in describing the growth pattern as shown by the highest R² and the lowest MSE (0.951 and 22.42, respectively), followed by Gompertz (0.948 and 26.79, respectively), Logistic (0.941 and 30.32, respectively) and Brody (0.873 and 23.56, respectively). The correlation between parameters A and k were found to be negative, ranging from -0.87 to - 0.52, indicating that animals with lower rate of maturing tended to be heavier at maturity. The use of non-linear model is useful in summarizing the entire lifespan weight-age data points that is usually time consuming in their analysis. The study of growth pattern is important to determine the optimum weight and age for replacement does and slaughter.
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