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Estimation of body weight growth curve parameters of Katjang-Boer crossbred

¹Mohd. Hafiz, A.W, ²Mohamad Hifzan, R., ¹ Izuan Bahtiar, A.J. and ³Nurulhuda, M.O

¹Livestock Science Research Centre, MARDI Muadzam Shah, 26700 Muadzam Shah, Pahang
²Livestock Science Research Centre, MARDI Headquarters, P/O Box 12301, General Post Office, 50774 Kuala Lumpur
³Livestock Science Research Centre, MARDI Kluang, 86009 Kluang, Johor

Malaysian J. Anim. Sci. 2020 23(2): 40-46

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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 KatjangBoer 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
R
2
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.