{"topic_id":"AAFCO_Ch6_dl_methionine","category":"aafco","context":"---\ntopic_id: \"AAFCO_Ch6_dl_methionine\"\ncategory: \"aafco\"\ntitle: \"AAFCO Ch6 dl methionine\"\nlang: en\nsource_document: \"AAFCO Model Pet Food Regulations\"\ncitation:\n  authority: \"AAFCO wp-content/uploads PDF\"\n  title: \"AAFCO Ch6 dl methionine\"\n  url: \"\"\n  retrieved: \"2026-07-21\"\n  ref: \"\"\n  doc_type: \"official source\"\n  needs_review: true\nauthority_tier: T1\nauthority_tier_basis: \"T1:std-body\"\nauthority_tier_date: 2026-08-04\n---\nAAFCO Ch6 definition 6.2 DL-Methionine is a product containing a minimum of 99% racemic 2-amino-4-(methylthio)butanoic acid; the percentage of DL-Methionine must be guaranteed (Adopted 1957, Amended 1975, 1978, 1989, 2005, 2009, Adopted 2011; 21 CFR 582.5475; IFN 5-03-086). Methionine is an essential amino acid for both dogs and cats; per the AAFCO 2014 cat food nutrient profile (DM basis), the methionine minimum is 0.62% for Growth & Reproduction and 0.20% for Adult Maintenance (methionine-cystine 1.10% / 0.40% respectively), while the dog profile sets methionine at 0.35% (G&R) / 0.33% (Adult) DM. DL-Methionine is the synthetically produced racemic form used to supplement plant-protein-based formulas (corn gluten, soy) that are relatively low in methionine. Heavy supplementation acidifies urine, a property deliberately used in some urinary-health formulations.\n","sources":["AAFCO wp-content/uploads PDF — AAFCO Ch6 dl methionine (retrieved 2026-07-21)"],"source":{"authority":"AAFCO wp-content/uploads PDF","title":"AAFCO Ch6 dl methionine","url":"https://www.aafco.org/","retrieved":"2026-07-21","ref":"","doc_type":"official source","source_document":"AAFCO Model Pet Food Regulations","verification_file":""},"source_document":"AAFCO Model Pet Food Regulations","source_file":"","trust":{"authority_tier":"T1","fidelity":"verbatim","license":null,"display_grade":"A"},"tokens_estimated":111,"generated_at":"2026-07-16","tip":"Use /api/v1/topics to discover more topics. /api/v1/nutrient for precise single-point queries. /api/v1/cross_compare for 2-3 standard comparisons."}