Performance of laying hens fed on practical diets containing different levels of supplemental biotin during the rearing and laying stages.

1. The effect of biotin supplementation of low-biotin practical diets during rearing and laying stages on performance was studied in White Leghorn-type laying hens. 2. Biotin supplementation during rearing did not have any apparent effect on the condition of the bird at point-of-lay or on subsequent laying performance. 3. Biotin supplementation during lay did not have any beneficial effect upon egg number, egg size or food intake or food conversion efficiency. 4. Internal egg quality, as reflected by albumen height, was slightly improved by biotin supplementation of layer's diet. 5. Input-output relationships were calculated for the incorporation of biotin in egg yolk. 6. Metabolic measurements suggested that biotin concentration in egg yolk was the best criterion of biotin status in the hen. 7. It is concluded that practical diets contain sufficient biotin to support optimum egg-laying performance in hens.