Inheritance of cow durability for linear type traits.

Final score and 14 linear type traits from appraisal by the Holstein Association were analyzed to assess inheritance of cow durability. Change of type scores from first to second parity (second minus first) was cow durability. Score for first parity, change of score from first to second parity, and FCM were simultaneously evaluated with a multiple-trait mixed model for each type trait. First analysis did not allow missing scores of cows for second parity, but subsequent analysis permitted missing data for second parity. When cows were required to have type scores for second parity, heritabilities for change of score were from zero (rear legs and foot angle) to 6% (final score). Genetic correlations of FCM and change of score were from -.35 (rump angle) to .24 (stature). When cows were not required to have type scores from second lactation, heritabilities for change of score were less than 8% for all traits except udder depth (17%). Except for dairy form and fore udder attachment, all genetic correlations of type scores from first lactation and change of score were positive. Seemingly, little new knowledge of linear type traits for ranking of sires was provided by appraisal of cows after first parity.