Changes in genetic variances with increased inbreeding of beef cattle

Data on performance traits from a herd of Hereford cattle composed of inbred lines and linecross groups were analyzed to estimate within- and among-line genetic variances and to evaluate how these variances changed with increased inbreeding. Within-line variances were highly erratic while among-line variances tended to be somewhat more consistent. Changes in variances with increased inbreeding did not generally follow the theoretical expectations for the redistribution of genetic variances.