Wagyu Beef Grades Marbling Science

Japan — Tajima cattle lineage documented Edo period; modern wagyu grading BMS system established 1975 by Japan Meat Grading Association

Wagyu (和牛, Japanese beef) grading in Japan uses the Japan Meat Grading Association's BMS (Beef Marbling Score) system from 1-12 and a yield grade A-C. True wagyu breeds: Tajima-gyu (Hyogo Prefecture — produces Kobe beef), Omi-gyu (Shiga), Matsusaka-gyu (Mie), Yonezawa-gyu (Yamagata). The intramuscular fat (sashi) in wagyu has a different fatty acid composition than standard cattle — higher oleic acid content (similar to olive oil) with a lower melting point (25-30°C vs 40°C for regular beef fat). This means wagyu fat melts at body temperature, creating the characteristic rich, silky texture. BMS 10-12 (A5 grade) contains more fat by weight than protein in the leanest cuts.

• Both grade beef by intramuscular fat — USDA Prime parallels BMS 4-5; A5 wagyu exceeds USDA grading ceiling → USDA Prime beef marbling grading American
• Both are regional breed-specific beef cultures with protected designations — Charolais muscular vs wagyu fatty expresses different ideal → Boeuf de Charolais terroir beef culture French

Sweet, rich, buttery fat that melts at body temperature — beef umami with oleic acid creating olive oil-like silkiness