02882naa a2200421 a 450000100080000000500110000800800410001910000180006024501860007826000090026452016630027365000210193665000160195765000210197365000180199465000140201265000120202665000180203865000230205665000130207965000160209265000200210865000110212865000200213965000220215965000260218165300260220765300200223370000240225370000160227770000240229370000210231770000200233870000170235870000210237570000180239677300460241420695262017-05-11       2017    bl uuuu     u00u1 u    #d1 aFRANCO, S. M.  aEstimation of optimal ratios of digestible phenylalanine + tyrosine, histidine, and leucine to digestible lysine for performance and breast yield in broilers.h[electronic resource]  c2017  aABSTRACT Three experiments were carried out to estimate the optimal ratios of digestible phenylalanine + tyrosine (Phe + Tyr), histidine (His), and leucine (Leu) relative to digestible lysine (Lys) for performance and carcass criteria of Cobb-500 broilers from 8 to 17 d of age. In each experiment, 160 male chicks were allocated to a completely randomized experimental design with eight replicate pens, each receiving five dietary treatments. A common, semi-purified basal diet was formulated to meet all dietary recommendations except for those of the tested amino acids (i.e., Phe + Tyr, His, and Leu). Growth performance and carcass characteristics data were analyzed using various requirement-estimation models, including 95% of the quadratic regression, linear response plateau (LRP; i.e., stepwise regression), LRP-to-quadratic regression ratio; and quadratic broken line (QBL). Graded digestible Phe + Tyr ratios elicited a quadratic response (P &lt 0.05) in body weight gain and linear responses (P &lt 0.05) in breast and breast fillet weights. Linear effects (P &lt 0.05) were also observed when graded ratios of digestible His were fed for feed intake and weight gain, and quadratic responses (P &lt 0.05) were noted for feed conversion ratio and breast and breast fillet weights and yields. Graded Leu ratios elicited quadratic responses (P &lt 0.05) in feed intake, weight gain, and breast and breast fillet weight and yield. Based on growth and carcass parameters, the estimated ideal digestible ratios of Phe + Tyr, His, and Leu relative to digestible Lys were 112, 38, and 104%, respectively, for broiler chicks raised from 8 to 17 d of age.  aAnimal nutrition  aBreast meat  aBroiler chickens  aDigestibility  aHistidine  aLeucine  aphenylalanine  aPoultry production  atyrosine  aAminoácido  aDigestibilidade  aEnzima  aFrango de corte  aNutrição animal  aSistema de produção  aDigestible amino acid  aPeito de frango1 aTAVERNARI, F. de C.1 aMAIA, R. C.1 aBARROS, V. R. S. M.1 aALBINO, L. F. T.1 aROSTAGNO, H. S.1 aLELIS, G. R.1 aCALDERANO, A. A.1 aDILGER, R. N.  tPoultry Sciencegv. 96, p. 829-837, 2017.