Effect of Proteins Low in Tryptophane on Growth of Chickens and on Laying Hens Receiving Nicotinic Acid-Low Rations

Abstract

The nicotinic acid requirement of chickens was influenced by the protein content of the ration. The presence of an excessive amount of a protein low in tryptophane (e.g., gelatin or zein) in purified, nicotinic acid-low rations depressed the growth rate of young chickens and increased the severity of nicotinic acid deficiency symptoms (blacktongue, perosis, etc.). Gelatin was about three times more active than zein in this respect. The depressing effect was overcome by the addition of nicotinic acid or tryptophane to the ration. A dietary source of nicotinic acid was not apparently required if sufficient tryptophane was present in the ration. The New Hampshire chick may require at least 5 mg of nicotinic acid per 100 gm of diet under certain extreme conditions. By the addition of bone ossein to a highly purified ration, it was possible to obtain a nicotinic acid deficiency in laying hens with a resulting drop in egg production, body weight, and hatchability. By the same procedure a nicotinic acid deficiency was produced in young chickens receiving a practical ration high in corn and corn products. A definite depression in growth rate and an increase in nicotinic acid deficiency symptoms were obtained by feeding certain combinations of arginine, glycine, and alanine. Thus, at least part of the depressing action of gelatin may be accounted for by its amino acid content.