title: Advances in protein-amino acid nutrition of poultry.
abstract: The ideal protein concept has allowed progress in defining requirements as well as the limiting order of amino acids in corn, soybean meal, and a corn-soybean meal mixture for growth of young chicks. Recent evidence suggests that glycine (or serine) is a key limiting amino acid in reduced protein [23% crude protein (CP) reduced to 16% CP] corn-soybean meal diets for broiler chicks. Research with sulfur amino acids has revealed that small excesses of cysteine are growth depressing in chicks fed methionine-deficient diets. Moreover, high ratios of cysteine:methionine impair utilization of the hydroxy analog of methionine, but not of methionine itself. A high level of dietary L: -cysteine (2.5% or higher) is lethal for young chicks, but a similar level of DL: -methionine, L: -cystine or N-acetyl-L: -cysteine causes no mortality. A supplemental dietary level of 3.0% L: -cysteine (7x requirement) causes acute metabolic acidosis that is characterized by a striking increase in plasma sulfate and decrease in plasma bicarbonate. S-Methylmethionine, an analog of S-adenosylmethionine, has been shown to have choline-sparing activity, but it only spares methionine when diets are deficient in choline and(or) betaine. Creatine, or its precursor guanidinoacetic acid, can spare dietary arginine in chicks.
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, 1207 W. Gregory Drive, Urbana, IL 61801, USA. dhbaker@uiuc.edu
authors.forename: David H
authors.initials: DH
authors.lastname: Baker
mesh_terms: D000596:Amino Acids / Q000009:adverse effects / Q000378:metabolism*; D000818:Animals; D019587:Dietary Supplements; D005247:Feeding Behavior; D011200:Poultry / Q000378:metabolism*; D011201:Poultry Diseases / Q000209:etiology / Q000378:metabolism*; D030262:Soybean Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D000596:Amino Acids; D030262:Soybean Proteins