JMGA (Japanese Meat Grading Association) Beef Carcass Grading Standard has been developed to measure those carcasses that are yielding higher marble scores. In 2008 Japan raised the bar on their grading standard whereby the BMS (Beef Marble Score) grade range is 3-12 (eliminating 1 and 2) and now a BMS 3 requires a min. IMF% of 21. If the US is going to raise cattle for export to Japan or compete with Japanese imports, it's important to have a fundamental understanding of the Japanese meat grading system.
Japanese carcasses are cut or ribbed between the sixth and seventh rib throughout Japan. There are three yield grades: A, B and C - classified by yield percentages estimated by an equation. There are five quality grades: 1, 2, 3, 4 and 5 - based on marbling, meat color and texture, and fat color and quality. Yield score is determined by an estimated cutability percentage that is calculated by an equation which includes four carcass measurements. The measurements are obtained at the sixth and seventh rib section. The yield grading is absolutely objective, delivering an estimated yield percentage as follows.
Grade A - 72% and above
Grade B - 69% and above
Grade C - under 69%
The meat quality scores are determined in terms of beef marbling, meat color and brightness, firmness and texture of meat, colour, lustre and quality of fat. The relationship between beef marbling evaluation and classification of grade is as follows:
Poor — 1
Below Average — 2
Average — 3-4
Good — 5-7
Excellent — 8-12
Meat color is evaluated by the Beef Color Standard prepared as seven continuous standards. The average color range is from No. 1 to No. 6 and carcasses in this color range can be graded in 'Grade 3 or upper grades'. Beef 'brightness' is also a factor in this evaluation. Firmness and texture of meat are evaluated by visual appraisal and also classified into five grades. The firmness measure ranges from very good to inferior and the texture of the meat is evaluated on a scale from very fine to coarse. The color, lustre and quality of fat is evaluated objectively against the Beef Fat Standards prepared as seven continuous standards. The remaining two factors, lustre and quality, are evaluated simultaneously by visual appraisal.
In recent years the Japanese have been focusing on developing objective carcass measurement utilitising the latest digital camera technology and image analysis software (Beef Analyzer II) to calculate important traits like;
•Rib Eye Area
•Rib Eye Shape
•Fineness/ Coarseness Index - Marbling
This technology is currently in use in the US (3 cameras) and Australia (1 camera) as a research tool to collate accurate carcass data for possible use in parameter estimation for genetic analysis(BLUP). This technology was recently presentation at the annual Wagyu Conference in Coeur d' Alene by Japanese Researcher and developer; Prof Keigo Kuchida from Obihiro University. Below is a image taken with the technology here in the US with the Rib Eye traced.
For more information about Japanese BMS Grading, please view the following documents.