Differences in stride between healthy ostriches (Struthio camelus) and those affected by tibiotarsal rotation.

Twenty healthy ostriches (ten cocks and ten hens), and twenty birds with tibiotarsal rotation (nine cocks and 11 hens) (14 months old) were isolated, hooded and weighed. A run (50 m x 2.5 m) was divided into sections marked 5 m, 10 m, 15 m and 20 m. Time taken for each bird to pass these points was recorded and speed computed. The degree of tibiotarsal rotation in the right foot was mean +/- SEM, 156 +/- 2.69 degrees. Comparisons between left and right foot length in healthy birds showed no significant differences. Foot length was significantly lower in tibiotarsal rotation (P = 0.03). The right foot in tibiotarsal rotation was significantly shorter than the left foot. The number of strides per each 5 m division were significantly (P < 0.05) greater in tibiotarsal rotation by comparison with healthy birds. At 20 m, healthy cocks had more strides than hens. The stride length in hens was significantly (P < 0.05) greater than cocks at 5, 10 and 15 m, respectively, but lower throughout in tibiotarsal rotation (P = 0.001). The speed of hens was significantly (P < 0.05) greater than cocks. Tibiotarsal rotation resulted in significantly (P < 0.05) reduced speeds. Hens may be able to escape danger faster than cocks. The occurrence of tibiotarsal rotation necessitates consideration of genetics, management, sex, nutrition and growth rates.