Hock angles of dairy heifers in two management systems

Hock angles were measured in 30 Holstein heifers in one herd housed either indoors on concrete slats or out of doors on dirt. Two examinations were made, i.e. at 12-13 and 24-26 months of age. Overall, the heifers had straight limbs; the mean value of the hock angle was 167.3 degrees +/- 0.7 (SEM) (range 154.3-177.4 degrees). Hock angles decreased with age in each group, but the difference between the first and second examinations was significant only for outdoor-housed heifers (P < 0.05). At the first examination, mean hock angles were not significantly different between the two groups (169.5 degrees +/- 1.6 vs 168.1 degrees +/- 1.6), but at the second examination indoor-housed heifers had significantly greater mean hock angles than heifers housed out of doors (167.4 degrees +/- 1.0 vs 164.2 degrees 1.3) (P < 0.05). Heifers housed indoors on concrete slats appeared to retain their straight-angled hocks.