Heritabilities (ĥ2) and genetic correlations (rG) were estimated by regression of offspring on sire in two replicate, unselected lines of mice. Traits were associated with growth, feed efficiency, fat deposition and lean tissue. The ĥ2 for growth traits ranged from .34 to .42, except for 3-wk body weight, which was only .05. The ĥ2 for feed efficiency was .28. Ranges in ĥ2 were .45 to .50 for f...