[Toxicological research on a protein-vitamin B12 concentrate in broiler chicks].

Studied were the acute and the subchronic toxicity, and the total tolerance of birds with regard to the Bulgarian protein-vitamin concentrate B12 (PVC-B12) with manifested activity of 230 mg per kilogram. With single introduction into the crop at rates of up to 20 g/kg PVC-B12 had no unfavourable effect on the health of birds. The same applied to its manifold use over a period of 10 days when given with the feed in amounts that exceeded ten and twenty times the recommended prophylactic and stimulating doses. As feed supplement at rates of 4 and 12 g/100 kg in the course of 56 days the preparation did not induce changes in the appetite, behaviour, general condition, clinical and biochemical composition of the blood, and structural organization and development of the viscera.