{
  "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.",
  "abstract_shown": true,
  "affiliations": [
    "Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, 72701, United States.",
    "Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, 72701, United States. Electronic address: bp032@uark.edu."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "K B Nelson"
    },
    {
      "affs": [
        0
      ],
      "name": "S W Hufford"
    },
    {
      "affs": [
        0
      ],
      "name": "R L Drysdale"
    },
    {
      "affs": [
        0
      ],
      "name": "L S Parisi"
    },
    {
      "affs": [
        0
      ],
      "name": "M B Williams"
    },
    {
      "affs": [
        0
      ],
      "name": "L J Urban"
    },
    {
      "affs": [
        0
      ],
      "name": "J C Valencia Beltran"
    },
    {
      "affs": [
        0
      ],
      "name": "M T Kidd"
    },
    {
      "affs": [
        1
      ],
      "name": "B W Parsons"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2w2v19yh5ajew.bib",
  "cited_by": 0,
  "doi": "10.1016/j.psj.2026.107901",
  "fulltext_url": "https://europepmc.org/articles/PMC13677383",
  "id": "2w2v19yh5ajew",
  "issns": [
    "0032-5791",
    "1525-3171"
  ],
  "landing_url": "https://europepmc.org/article/MED/42849228",
  "language": "eng",
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1103|Animal Nutrition and Physiology"
    ]
  ],
  "openalex": "W7220459928",
  "pdf_url": "https://europepmc.org/articles/PMC13677383?pdf=render",
  "pmcid": "PMC13677383",
  "pmid": "42849228",
  "published": "2026-10-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2w2v19yh5ajew.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:10Z",
      "native_id": "MED:42849228",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42849228"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "openalex:1103|Animal Nutrition and Physiology",
      "subfield": "zoology-behaviour"
    }
  ],
  "title": "Requirement of phenylalanine and phenylalanine + tyrosine in broiler chickens fed purified amino acid diets and assessment of phenylalanine as a source of tyrosine.",
  "title_text": "Requirement of phenylalanine and phenylalanine + tyrosine in broiler chickens fed purified amino acid diets and assessment of phenylalanine as a source of tyrosine.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:10Z",
  "url": "https://research.draconitic.com/paper/2w2v19yh5ajew",
  "venue": "Poultry science",
  "versions": []
}