| Abstrakt: |
The objective of this study was to compare the growth curve parameters derived from non-linear regression models using body weight data of Brakmas and Bali cattle. Four non-linear models, namely Brody, von Bertalanffy, Gompertz and Logistic, were fitted to the body weight data collected from 279 Brakmas (range in age from 1 to 15 y) and 74 Bali (range in age from 1 to 10 y) cows. Coefficient of determination (R²), residual mean square (MSE) and mean of absolute deviation (MAD) were used to determine the best model to describe the growth pattern of the cattle. For both cattle breeds, the Logistic model showed the highest R² value at 0.967, followed by Gompertz, von Bertalanffy and Brody with R² values at 0.966, 0.966 and 0.964, respectively. Logistic model also showed the lowest MSE at 1057.1, followed by Gompertz, von Bertalanffy and Brody that yielded 1080.5, 1094.7 and 1138.7 of MSE, respectively. Supporting these results, Logistic model showed the lowest MAD at -6.17 compared to Gompertz (-5.78), von Bertalanffy (-1.65) and Brody (1.82). Brakmas cattle showed higher mature weight compared to Bali cattle of 328.8±4.917 kg and 270.4±4.419 kg, respectively, as estimated by Logistic model. However, Bali cattle showed higher rate of maturing at 0.109±0.011 compared to Brakmas cattle (0.089±0.005) which indicated that Bali cattle would likely attain its mature weight earlier than Brakmas cattle. This was further explained by the negative correlation between mature weight and rate of maturing where Brakmas cattle showed higher negative correlation coefficient compared with Bali cattle. The correlation between mature weight and maturing rate of Brakmas and Bali cattle were -0.528 and -0.170, respectively. It is concluded that the use of non-linear model is useful as it could summarize the weight-age relationship into several biologically interpreted parameters compared to the entire lifespan weight-age data points that are difficult to interpret. [ABSTRACT FROM AUTHOR] |
