The use of 'bending' in multiple trait selection of Border Leicester–Merino synthetic populations

Abstract

The consistency of phenotypic and genetic parameters estimated for various body weight and wool characters in Border Leicester-Merino synthetic populations was investigated by calculating the eigenvalues of matrices of phenotypic covariances (P), genetic covariances (G), and the product of the inverse of the phenotypic with the genetic covariance matrix (P-1G). If these estimates were found to be inconsistent (non-positive definite), the bending technique was applied before genetic selection indices were calculated. In general, the P were positive definite, but the G or P-1G were always non-positive definite. The results suggest that P and G should always be checked carefully before genetic selection indices are calculated. The bending technique was quite effective in giving reasonable results for accuracy of selection.