The effects of different levels of dietary biotin on the performances and on bone growth in the broiler

Biotin deficiency in the broilers' diet causes reduction of growth rate and food conversion, clinically the appearance of cutaneous lesions that are particularly severe around the beak and in the plantar regions, and long bone deformities (Anderson and Warnich, 1970; Riddel, 1981; Bain et al., 1989). It has been demonstrated that 21-day old chicks fed biotin deficient diets showed thicken-ing of the tibiotarsuscortex. (Watkins et al., 1989). In order to avoid nutritional disorders and to ensure the “optimal” dosage, broiler biotin requirements are still undefined. Biotin is found in both animal and vegetal tissues in small quantities and in variable amounts; this is due to intrinsic factors in the feed (biotin binding protein) and to extrinsic factors like technologic processing, that limit biotin availability. Frigg (1976 and 1984) and Whitehead et al.(1982) reported that chickens are not able to use biotin from wheat, and they can only use small amounts of biotin from barley, broomcorn, oat, bran and man-ioc; nevertheless they are able to assimilate all the biotin found in corn, different oil-seeds meals and in tankage. In this context, we evaluated biotin supplementation in broilers performances and bone growth