Phenotypic correlations between live body weight and linear body measurements and Regression Equations for prediction of live body weight in Tswana, Dorper, Damara, Meat-master and Karakul sheep breeds in Botswana

Abstract

Abstract The study was conducted to determine the relationship between body weight and other morphological traits, and the practicality of using linear body measurements to estimate body weight. Correlation coefficients were determined from a total of 595 sheep (Damara: 79, Dorper: 177, Karakul: 135, Meat-master: 156 and Tswana: 48), while regression equations were estimated from a total of 94 sheep (Damara: 20, Dorper: 30, Karakul: 16, and Meat-master: 28) using Statistical Analysis System (SAS) 9.4. The highest, strong and positive correlation coefficients were found between body weight and heart girth in both sexes across the different sheep breeds, with males having high correlation coefficients than females. Body length in males across the breeds had a much higher correlation coefficient with body weight compared to height at withers. Linear body measurements like heart girth, body length, height at withers, neck length, cannon bone length, cannon bone circumference and scrotal circumference in males were used to estimate body weight of Dorper, Damara, Meat-master and Karakul sheep breeds. Heart girth accounted for most of the variability in the prediction models of all the breeds, irrespective of sex, except for Damara males. Heart girth and body length explained most of the variability in the model used to predict body weight of Damara males, which means these traits can be used as selection criteria for body weight. Addition of more independent variables increases the accuracy of the prediction equation.