Association between visual marbling score and chemical intramuscular fat with camera marbling percentage in Australian beef carcasses

This study assessed the precision and accuracy in the prediction of chemical intramuscular fat (IMF%), Meat Standards Australia (MSA) marbling score and AUS-MEAT eye-muscle area (EMA) using Meat Imaging Japan (MIJ) prototype camera systems. Eleven carcass datasets from the Beef Information Nucleus (BIN) project were compiled with carcass grading, IMF% and camera data. Camera prediction of IMF%, MSA marbling score and EMA was assessed using a leave-one-out cross validation method. There was an association between MIJ mirror and MIJ-30 camera traits and IMF%, MSA marbling score and EMA. However, for both prototypes precision varied for IMF% (R² = 0.4–0.5, RMSECV = 1.5–1.6%), MSA marbling (R² = 0.3–0.5, RMSECV = 57.5–59.3) and EMA (R² = 0.7–0.6, RMSECV = 4.1–5.8 cm² ). Accuracy also fluctuated with average bias values of 1.7–1.8%, 45.8–40.0 units and 3.8–4.1 cm² for IMF%, MSA marbling score and EMA respectively. Key differences between carcass and camera traits and processing factors affecting the grading site are likely to have contributed to this variation.