Anatomical characterization of hoof growth pattern in six Iranian sheep breeds and its possible implication for trimming recommendations.

The objective of this study was to compare hoof anatomy, hoof growth pattern, and hoof weight-bearing surface of six different Iranian sheep breeds to identify possible differences in the hoof anatomical features that could help to minimize adverse effects of hoof trimming methods. Front and hind hooves of 2-year-old, previously untrimmed, pastured dairy ewes of six Iranian breeds (Afshari, Moghani, Kurdi, Makoui, Chaleshtori, and Lori-Bakhtiari; n = 180 ewes; 30 ewes per breed) were collected after slaughter. Medial and lateral claws were incised sagittally and anatomical measurements such as toe length, heel height, toe height, sole thickness, sole length, and toe angle were recorded in each claw. Data were analyzed using mixed model equations including breed, claw (lateral or medial), hoof (front or hind) and their interactions as fixed effects, and ewe as random effect. Breed differences were observed for all hoof measurements (P < 0.05). Chaleshtori sheep had higher measurements for most of the traits studied while Afshari and Makoui sheep had lower measurements. All measurements, except for toe length and toe height to solar surface to heel height ratio, were significantly greater in the front hooves than in the hind hooves (P < 0.05). Soles were longer in the medial claws compared to the lateral claws of the front hooves (P < 0.05). Results suggest the observed breed differences could interfere with establishing a standard, uniform hoof trimming method for sheep. For instance, it might be possible that while Afshari and Makoui sheep could require more conservative trimming, Chaleshtori sheep could require to be trimmed more. In consequence, hoof trimming methods might need to be adjusted to specific breed characteristics to avoid possible tissue damage.