The Journal of Nutrition 1961 Volume.73 No.2
Lysine Toxicity in the Chick* 1 J. D. JONES2 Department of Animal Husbandry, Iowa State University, Ames, Iowa That a dietary excess of most of the EXPERIMENTAL common amino acids, when fed to experi Day-old Cornish X White Rock cross mental animals receiving either complete bred chicks, obtained commercially, of both diets or diets lacking an essential nutrient, sexes were housed in electrically heated causes growth retardation is well docu batteries with raised screen floors. Ten to mented (Harper et al., ’55), although a 12 chicks were allotted at random to each satisfactory explanation for this observa pen using at least 4 pens per treatment. tion has not been proposed. L-lysine has All of the diets were offered ad libitum and been one of the amino acids most fre contained the following (in per cent): quently studied as a supplement for dietary casein, 18; gelatin, 10; salts 5 (Briggs et proteins, and both adverse and beneficial al., ’43), 6; com oil, 4; glycerol, 1; DL-me- effects have been observed. Levels of thionine, 0.3; choline chloride, 0.2; inosi lysine up to 4% , when added to adequate tol, 0.1; and vitamins (in mg per 100 gm and limiting protein rations, caused a of ration) as follows: thiamine-HC1, 0.6; severe growth depression when fed to day- riboflavin, 0.9; niacin, 5; Ca pantothenate, old chicks, which was partially overcome 2.0; pyridoxine, 0.8; biotin, 0.02; folic acid, by added gelatin (Anderson and Combs, 0.4; a-tocopherol, 0.3; vitamin Bi2, 0.003; ’52); also growth depression and toxicity and menadione, 0.05.
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