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The monthly hoof horn production rate, monthly horn loss and the quality of the coronary
horn was examined in the dorsal part of the hoof capsule of Przewalski horses. In order to
demonstrate alterations induced by domestication, the results of this study were then
compared to related data on the hooves of domestic horses in the literature and a concurrent study on the hoof of warm-blooded horses (KÖNIG, in preparation).
The horn production rate and the horn loss were measured on the hooves of 15 Przewalski
horses. The hooves were marked, and each month the downward movement of the markers
towards the distal margin of the hoof capsule was measured over a period of two and a half
years. The annual mean values of the examined wild horses lie within the standard variation
of the values published for different domestic horse races. But a domestication-related effect can still be detected, because the values of the Przewalski horses, which were kept in a semi-reservate, show more seasonal variations than those of domestic horses. This difference between domestic and wild equides is most likely derived from the different housing condit ions. In the examined Przewalski horses, both the hoof horn production rate as well as the horn loss are significantly higher in the summer than in the winter time. The annual variations of the horn production rate are particularly influenced by the climatic conditions (environmental temperature and length of day light), but also by the differing seasonal locomotory activity of the horses and the varying food supply. The loss of horn, amongst others, is influenced by the seasonal variations in ground conditions, hoof horn quality, locomotory activity and the body weight of the horses. Another seasonality is apparent in the occurrence of broken-out horn chips in the hoof weight bearing margin, acting as an additional mechanism for hoof length regulation in horses which are kept in reservates and thus suffer from insufficient hoof horn abrasion.