Microstructure of the hoof capsule of pigmented and partial albino buffaloes.

In this study, atomic force microscopy (AFM), microtomography (MCT-2D and MCT-3D) and energy-dispersive X-ray fluorescence spectrometry (EDXRF) were used to generate parameters of the microstructure of the hoof capsule of pigmented and partial albino buffaloes. Seventy-two digits of adult pigmented buffaloes and 16 of partial albino buffaloes were used and equally divided into thoracic and pelvic limbs and medial and lateral claws. Fragments of 10 mm × 10 mm of the dorsal wall, abaxial wall and pre-bulbar sole were collected. The parametric assumptions were tested using a Shapiro-Wilk test (normality). The independent t-test was used to compare the means at a 5% significance level. AFM demonstrated that the hoof surface of pigmented buffaloes presented with higher average surface roughness (Ra) and root mean square roughness (Rms) (p < 0.05) than the hoof surface of partial albino buffaloes. MCT-2D revealed that pigmented buffaloes had extra tubular keratin with a higher density than intratubular keratin. No pores were observed in the hoof capsule of the buffalo digits. MCT-3D demonstrated that pigmented buffaloes have a higher percentage of large and intermediate horn tubules than partial albino buffaloes. However, this difference was not statistically significant. Partial albino buffaloes showed a statistically higher number of horn tubules/mm2 than pigmented buffaloes (p < 0.05). EDXRF revealed a higher amount of sulphur (S) in the hoof capsule of pigmented buffaloes, and the partial albino buffaloes presented a higher number of minerals such as calcium (Ca), potassium (K), zinc (Zn) and copper (Cu).

Mineral composition and microstructure of the abaxial hoof wall in dairy heifers after biotin supplementation.

The aim of this study was to evaluate the effect of daily biotin supplementation on the mineral composition and microstructure of the abaxial hoof wall in dairy heifers. The heifers were housed on a concrete floor and fed for weight gain more than 800 g per day, which is a challenging environment for the hoof. Twelve crossbred dairy heifers (Jersey × Holstein) were divided into two treatment groups. Animals in the control group (n = 6) received a diet without supplemental biotin, while the heifers in the biotin-supplemented feed group (n = 6) each received 20 mg of biotin daily for 120 days. Samples of the abaxial hoof wall were collected from the outer claw of the fore and hind limb, before and after supplementation. The samples were evaluated by X-ray fluorescence spectrometry, computed microtomography, atomic force microscopy and confocal laser scanning microscopy. Biotin supplementation increased the sulphur content and decreased the calcium and potassium content in the abaxial hoof wall. Biotin treatment also increased the percentage of horn tubules with smaller diameter marrow (17-51 µm). However, biotin did not influence the surface relief of the hoof wall, suggesting that its action is limited to the inner layers of the stratum corneum. Daily supplementation with 20 mg of biotin promoted changes in the mineral composition and microstructure of abaxial hoof wall of crossbred dairy heifers. These findings suggest biotin supplementation improves hoof quality and may help to understand the function of biotin in the stratum corneum.