Biotin deficiency may alter tibiotarsal bone growth and modeling in broiler chicks.

Forty-eight, day-old male broiler chicks (Hubbard x Hubbard strain) were fed purified diets with two levels of biotin (0 and 400 micrograms/kg) and two levels of linoleate (26.5 and 1.5 g/kg) in a factorially designed experiment to determine the effects of these nutrients on tibiotarsal bone growth and modeling. Chicks fed biotin-deficient diets (0 microgram/kg diet) exhibited varus deformities, footpad dermatitis, shortened tibiotarsi, and significantly higher bone densities and percentage bone ash. Anatomically there were two different bone modeling patterns. The mid-diaphyseal cortex was thickest laterally in chicks fed adequate biotin and thickest medially in biotin-deficient chicks. Periosteal bone appositional and bone formation rates, osteoid perimeter, and osteoid area of perimeter were reduced in tibiotarsi of chicks fed diets deficient in biotin compared with effects in chicks fed adequate biotin. Altered bone modeling patterns and quantitative differences in bone histomorphometry suggest a relationship between the effects of biotin on bone growth and the development of varus limb deformities.