title: Effect of feeding reduced protein, amino acid-supplemented diets on nitrogen and energy balance in grower pigs.
abstract: Two experiments were conducted to determine the effect of feeding reduced CP, amino acid (AA)-supplemented diets on the nitrogen (N) and energy (E) balance of grower pigs. In Exp. 1, 24 barrows (22.2 kg BW) were fed corn-soybean meal (C-SBM) diets containing either 16% CP, 12% CP, or 12% CP supplemented with lysine (LYS), tryptophan (TRP), and threonine (THR). After 6 d of adaptation to the diets and feeding frequency, a 5-d N and E balance trial was conducted. Supplementation of the 12% CP diet with LYS, TRP, and THR improved N retention ( P < .01) but failed to improve N retention to the level attained by pigs fed the 16% CP diet (P < .01). Efficiency of N retention was similar between pigs fed the AA-supplemented 12% CP diet and pigs fed the 16% CP diet (P > .10). Energy retention was increased by AA-supplementation of the 12% CP diet ( P < .10) to a level higher than that of pigs fed the 16% CP diet (P < .01). In Exp. 2, 60 barrows (21.7 kg BW) were fed one of the following diets: 16% CP; 12% CP diet supplemented with indispensable AA (IDAA) to simulate the 16% CP diet; 12% CP supplemented with LYS, TRP, THR, and dispensable AA N (DAAN); 12% CP supplemented with LYS, TRP, and THR; or a 12% CP negative control diet. After 6 d of adaptation to the diets and feeding frequency, a 5-d N and E balance trial was conducted. Nitrogen retention was improved (P < .01) by supplementing the 12% CP diet with LYS, TRP, and THR but remained inferior (P < .01) to that obtained when pigs were fed the other three diets. Pigs fed the 12% CP diet with LYS, TRP, THR, and DAAN supplementation retained less N (P < .07) than pigs fed the 16% CP but retained an amount similar (P > .10) to pigs fed the 12% CP diet with IDAA and DAAN supplementation. Pigs fed the 12% CP diet with LYS, TRP, and THR supplementation exhibited the highest efficiency of N retention (P < .01). Pigs fed the 12% CP diet supplemented with LYS, TRP, THR, and DAAN retained more (P < .01) E than pigs fed the 12% CP diet supplemented with IDAA and DAAN and more (P < .07) E than pigs fed either the 12% CP diet supplemented with LYS, TRP, and THR or the unsupplemented 12% CP diet. Pigs fed the 16% CP diet retained more (P < .06) E than pigs fed the 12% CP diet with IDAA and DAAN supplementation. Although the data show that the efficiency of N retention is greatest when LYS, TRP, and THR are supplemented to the 12% CP diet, maximal N retention is achieved only when the 12% CP diets are supplemented with both the deficient AA and a source of N for dispensable AA synthesis.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Kerr
authors.forename: R A
authors.initials: RA
authors.lastname: Easter
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage* / Q000494:pharmacology; D000641:Ammonia / Q000032:analysis; D000818:Animals; D001806:Blood Urea Nitrogen; D018753:Diet, Protein-Restricted / Q000592:standards / Q000662:veterinary*; D004734:Energy Metabolism / Q000502:physiology*; D005527:Food, Fortified; D008239:Lysine / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D011897:Random Allocation; D013552:Swine / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D013912:Threonine / Q000008:administration & dosage / Q000494:pharmacology; D014364:Tryptophan / Q000008:administration & dosage / Q000494:pharmacology; D014508:Urea / Q000097:blood
chemical_list: D000596:Amino Acids; D013912:Threonine; D000641:Ammonia; D014364:Tryptophan; D014508:Urea; D008239:Lysine; D009584:Nitrogen