Prediction of Body Weight from Body Measurements Using Regression Tree (rt) Method for Indigenous Sheep Breeds in Balochistan, Pakistan

The aim of this study is to estimate body weight from withers height, body length, and chest girth measurements by using Regression Tree (RT) Method. For this purpose, data were collected from 239 male sheep at yearling age (11-13 months) of five indigenous sheep breeds (Mengali (48), Balochi (48), Harnai (48), Beverigh (47) and Rakhshani (48)) reared in Balochistan, Pakistan. Bivariate relationships among body weight, withers height, body length, and chest girth measurements were calculated by using Pearson correlation coefficients. For RT method, body weight was used as a dependent variable, whereas withers height, body length, and chest girth measurements and breed were considered as independent variables. A highly significant correlation coefficient was detected between body weight and chest girth (r=0.742; P<0.01). Statistically significant correlation coefficients of body weight with withers height and body length were 0.419 (P<0.01) and 0.457 (P<0.01) respectively. In the current study, Regression Tree method illustrated that 72 % of variation in the body weight was explained by statistically significant variables; namely, withers height, body length, chest girth, and breed. Regression Tree method reflected the sheep with chest girth greater than 89 cm within all the sheep could produce the heaviest average body weight with 36.486 kg, and average body weight could increase with increasing chest girth, which was found considerably significant compared to others. Results on chest girth also supported previous reports in literature. It was concluded in the current study that Regression Tree Method could be efficient to predict body weight from withers height (P<0.001), body length (P<0.001), chest girth (P<0.001), and breed (P<0.001) at yearling sheep.