RELATIONSHIP BETWEEN BODY VOLUME AND BODY WEIGHT IN PELIBUEY EWES

Abstract

Background. In terms of animal management, the measurement of body weight (BW) is important in the design of nutrition and health programs. Objective. The objective of the present study was to evaluate the relationship between body volume (BV) and BW in Pelibuey ewe lambs and ewes. Methodology. For the model development, the BW and body volume (BV) were recorded in 406 Pelibuey ewe lambs and ewes ranging from two months to one years in age. All animals were clinically healthy, with a BW = 37.62 ± 10.63 kg. The BV was calculated using the heart girt (HG) and the body length (BL). BV was calculated according to the mathematical formulas for calculating the volume of a cylinder, considering biometric measurements in the calculation. The relationship between BV and BW was assessed by linear (Eq. 1), quadratic (Eq. 2) and allometric equation (Eq. 3). The goodness of fit of the regression models was assessed by the Akaike information criterion (AIC), Bayesian information criterion (BIC), coefficient of determination (R2), mean square error (MSE) and root mean square error (RMSE). Results. The correlation coefficient (r) between BW and BV was 0.89 (P < 0.001). The quadratic model had the higher value of coefficient of determination (R2= 0.81, and the lower MSE (4.17), RMSE (2.04), AIC (1163.64) and BIC (1175.66) values. The predictive ability of the three live weight prediction models was evaluated using k-folds validation (k = 10). Implications. The quadratic model had the higher coefficient of determination and lowest values were found for the mean square error (MSE) and mean absolute error (MAE). This model is practical and predicts with high accuracy the BW of the animals. Conclusion. Based on the evaluation approaches used in the present study and the close relationship between BW and BV in Pelibuey ewe lambs and adult ewes, the quadratic model was the mathematical model that had the best performance according to the goodness-of-fit evaluation.