No significant difference was found in hardness and
moisture content of hoof among treatments (P40.05,
Table 4). An increased hardness was observed from the
beginning to end of the experiment in all groups, with no
difference between treatments (P¼0.58). Lischer et al.
(2002) reported that the effect of biotin on hoof quality
could not be assessed adequately by macroscopic examination
in short periods. Sixty days in this study may not be
long enough to improve the hoof quality. Precise and
detailed assessment of hoof quality could be conducted by
light microscopic techniques. The hoof samples, taken from
the area of the stratum medium of dairy cow hoof on day 0
showed that there was more interspace in all the samples
(Fig. 2a–c), compared to the samples on 60 d (Fig. 2A–C).
The evidence in this study proved that biotin promoted
keratin content and reduced microcrack (the white parts in
the figures) in the hoof of dairy cows.