Relation of Dietary Cations to Arginine-lysine Antagonism and Free Amino Acid Patterns in Chicks

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Abstract
Broiler-strain chicks were fed from hatching to 4 weeks of age a basal purified diet containing 35% casein, 0.5% methionine and 1.5% glycine as sources of amino acids. The diets contained 1.2% arginine, 2.5% lysine, 0.4% potassium and had a cation to anion ratio of 1:1. Supplementation with either arginine·HCl or sodium and potassium salts of metabolizable acids produced marked growth stimulation. A combination of cations and arginine was even more beneficial but the effects were not additive. Not only did the cation supplement stimulate the growth rate to the same extent as 0.6% arginine, but it decreased the deficiency signs typical of arginine deficiency-ataxia and frizzled feathers. More significantly, both arginine and potassium acetate supplementation decreased plasma and muscle lysine, threonine and serine while increasing the levels of free arginine. A combination of the supplements gave plasma and muscle amino acid patterns highly similar to those observed in chicks fed a practical corn-soybean meal diet. It may be concluded that cation supplementation of this casein-based diet spares the arginine requirement and creates more favorable free amino acid patterns. It is postulated that the rate of arginine catabolism is decreased by the more positive cation balance.