Path coefficient and path analysis of body weight and biometric traits of Yankasa lambs

Abstract

Direct and indirect effects of seven predictor variables (withers height, body length, heart girth, shoulder width, head width, rump width and rump length) on body weight of 92 extensively managed Yankasa lambs aged 11.8±3.02 (females) and 12.5±2.56 (males) months were investigated using path analysis. Sex-associated difference was significant (P<0.05) only for withers height, with higher value recorded for male lambs. Pairwise correlations between body weight and zoometrical traits ranged from 0.59-0.95 and 0.61-0.92 for male and female lambs, respectively. The direct effect of heart girth on body weight was the strongest in both sexes (path coefficient of 0.81 and 0.87 in males and females, respectively). Head width (males) and body length (females) also positively (P<0.05) influenced body weight. The direct effects of other linear type traits on body weight in both sexes were non-significant as revealed by t-test. These traits were indirectly realized mostly via heart girth. Thus, they were expunged from the final regression equations to obtain much more simplified prediction models. The optimum multiple regression equation for male lambs included heart girth and head width, with a determination coefficient (R2 ) of 0.919 and determination coefficient of error of 0.081. In female lambs, however, the variables included in the final prediction model were heart girth and body length, with a determination coefficient of 0.893 and determination coefficient of error of 0.107. The forecast indices obtained in this study could aid in weight estimation, selection and breeding programmes.