Requirement of phenylalanine and phenylalanine + tyrosine in broiler chickens fed purified amino acid diets and assessment of phenylalanine as a source of tyrosine.
- 1Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, 72701, United States.
- 2Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, 72701, United States. Electronic address: [email protected].
Abstract
There is a paucity of information on the efficacy of Phe as a source of Tyr in chickens, a question that must be considered when expressing requirements for Phe and Tyr jointly (i.e. Phe + Tyr). The objectives of these experiments were to establish Phe and Phe + Tyr dose-response relationships in male Cobb 500 broilers using purified amino acid diets and to assess the efficacy of Phe as a source of Tyr. In Experiment I, Phe + Tyr requirement estimates were determined in diets devoid of Tyr. Dietary treatments were created by supplementing L-Phe in graded increments of 0.10% to achieve a range of 0.50 to 1.20% Phe. In Experiment II, Phe requirement estimates were determined using diets that contained excess Tyr (0.60%). Dietary treatments were created by supplementing L-Phe in graded increments of 0.10% to achieve a range of 0.20 to 0.90% Phe. In Experiment III, the efficacy of Phe as a source of Tyr was determined using a slope-ratio bioassay. Seven dietary treatments were created by supplementing 0.06, 0.12, and 0.18% of either L-Phe or L-Tyr to a purified basal diet that was devoid of Tyr and contained 0.60% Phe. There were 5 replicate pens of 5 male broilers per treatment in each experiment. In Experiments I and II, there was a quadratic effect of Phe on BW gain and gain:feed (P < 0.05). Linear one-slope broken-line regression analysis for gain:feed yielded an estimated Phe + Tyr requirement of 0.93% (R² = 0.96) in Experiment I and a Phe requirement of 0.44% (R² = 0.96) in Experiment II. In Experiment III, BW gain increased linearly in response to supplementation of both L-Phe and L-Tyr (P < 0.05). The estimated efficiency of L-Phe conversion to L-Tyr using multiple linear regression of BW gain on total Phe + Tyr intake ranged from 96.5 to 97.9% on a weight and molar basis. In conclusion, modern broilers can efficiently utilize Phe as a source of Tyr.
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BibTeX
@article{nelson2026requirement,
title = {{Requirement of phenylalanine and phenylalanine + tyrosine in broiler chickens fed purified amino acid diets and assessment of phenylalanine as a source of tyrosine.}},
author = {K B Nelson and S W Hufford and R L Drysdale and L S Parisi and M B Williams and L J Urban and J C Valencia Beltran and M T Kidd and B W Parsons},
journal = {Poultry science},
year = {2026},
month = oct,
doi = {10.1016/j.psj.2026.107901},
url = {https://europepmc.org/article/MED/42849228},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Requirement of phenylalanine and phenylalanine + tyrosine in broiler chickens fed purified amino acid diets and assessment of phenylalanine as a source of tyrosine.
AU - K B Nelson
AU - S W Hufford
AU - R L Drysdale
AU - L S Parisi
AU - M B Williams
AU - L J Urban
AU - J C Valencia Beltran
AU - M T Kidd
AU - B W Parsons
PY - 2026
DA - 2026/10/05
JO - Poultry science
DO - 10.1016/j.psj.2026.107901
UR - https://europepmc.org/article/MED/42849228
AB - There is a paucity of information on the efficacy of Phe as a source of Tyr in chickens, a question that must be considered when expressing requirements for Phe and Tyr jointly (i.e. Phe + Tyr). The objectives of these experiments were to establish Phe and Phe + Tyr dose-response relationships in male Cobb 500 broilers using purified amino acid diets and to assess the efficacy of Phe as a source of Tyr. In Experiment I, Phe + Tyr requirement estimates were determined in diets devoid of Tyr. Dietary treatments were created by supplementing L-Phe in graded increments of 0.10% to achieve a range of 0.50 to 1.20% Phe. In Experiment II, Phe requirement estimates were determined using diets that contained excess Tyr (0.60%). Dietary treatments were created by supplementing L-Phe in graded increments of 0.10% to achieve a range of 0.20 to 0.90% Phe. In Experiment III, the efficacy of Phe as a source of Tyr was determined using a slope-ratio bioassay. Seven dietary treatments were created by supplementing 0.06, 0.12, and 0.18% of either L-Phe or L-Tyr to a purified basal diet that was devoid of Tyr and contained 0.60% Phe. There were 5 replicate pens of 5 male broilers per treatment in each experiment. In Experiments I and II, there was a quadratic effect of Phe on BW gain and gain:feed (P < 0.05). Linear one-slope broken-line regression analysis for gain:feed yielded an estimated Phe + Tyr requirement of 0.93% (R² = 0.96) in Experiment I and a Phe requirement of 0.44% (R² = 0.96) in Experiment II. In Experiment III, BW gain increased linearly in response to supplementation of both L-Phe and L-Tyr (P < 0.05). The estimated efficiency of L-Phe conversion to L-Tyr using multiple linear regression of BW gain on total Phe + Tyr intake ranged from 96.5 to 97.9% on a weight and molar basis. In conclusion, modern broilers can efficiently utilize Phe as a source of Tyr.
SN - 0032-5791
SN - 1525-3171
ER -