title: Effect of l-glutamic acid supplementation on performance and nitrogen balance of broilers fed low protein diets.
abstract: The aim of this study was to evaluate the effect of protein reduction and supplementation of l-glutamic acid in male broiler diets. A total of 648 chicks of the Cobb 500 strain were distributed in a completely randomized design with six treatments and six replications with eighteen birds per experimental unit. The study comprised pre-starter (1-7 days), starter (8-21 days), growth (22-35 days) and final (36-45 days) phases. The first treatment consisted of a control diet formulated according to the requirements of essential amino acids for each rearing phase. The second and third treatments had crude protein (CP) reduced by 1.8 and 3.6 percentage points (pp) in relation to the control diet respectively. In the fourth treatment, l-glutamic acid was added to provide the same glutamate level as the control diet, and in the last two treatments, the broilers were supplemented with 1 and 2 pp of glutamate above that of the control diet respectively. The reduction in CP decreased the performance of broilers and the supplementation of l-glutamic acid did not influence performance when supplied in the diets with excess of glutamate. The lowest excreted nitrogen values were observed in the control diet, and treatments 2 and 3, respectively, in comparison with treatments with the use of l-glutamic acid (5 and 6). Retention efficiency of nitrogen was better in the control diet and in the treatment with a reduction of 1.8 pp of CP. It was verified that the serum uric acid level decreased with the CP reduction. A reduction in CP levels of up to 21.3%, 18.8%, 18.32% and 17.57% is recommended in phases from 1 to 7, 8 to 21, 22 to 35 and at 36 to 42 days, respectively, with a level of glutamate at 5.32%, 4.73%, 4.57%, 4.38%, also in these phases.
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: R M
authors.initials: RM
authors.lastname: Bezerra
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: F G P
authors.initials: FG
authors.lastname: Costa
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: P E N
authors.initials: PE
authors.lastname: Givisiez
authors.affiliation: Department of Animal Science, Federal University of Ceará, Fortaleza, Ceará, Brazil.
authors.forename: E R
authors.initials: ER
authors.lastname: Freitas
authors.affiliation: Department of Animal Science, State University of Acarau Valley, Sobral, Ceará, Brazil.
authors.forename: C C
authors.initials: CC
authors.lastname: Goulart
authors.affiliation: Department of Animal Science, Federal University of Rio Grande do Norte, Macaíba, Rio Grande do Norte, Brazil.
authors.forename: R A
authors.initials: RA
authors.lastname: Santos
authors.affiliation: Department of Animal Science, Federal University of Rio Grande do Norte, Macaíba, Rio Grande do Norte, Brazil.
authors.forename: J G
authors.initials: JG
authors.lastname: Souza
authors.affiliation: Department of Veterinary Medicine, Federal University of Campina Grande, Patos, Paraíba, Brazil.
authors.forename: P A
authors.initials: PA
authors.lastname: Brandão
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Lima
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Melo
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: V P
authors.initials: VP
authors.lastname: Rodrigues
authors.affiliation: Ajinomoto of Brazil, São Paulo, SP, Brazil.
authors.forename: E T
authors.initials: ET
authors.lastname: Nogueira
authors.affiliation: Department of Animal Science, Federal University of Paraíba, Areia, Paraíba, Brazil.
authors.forename: D V G
authors.initials: DV
authors.lastname: Vieira
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D018698:Glutamic Acid; D009584:Nitrogen
keywords: amino acid; feed conversion; nitrogen; nutritional requirement