Abstract
Pork carcasses (n = 199) were selected to represent the current U.S. population: 25% US 1, 36% US 2, 25% US 3, and 14% US 4. Carcasses were selected at six processing plants from five companies by a trained USDA grader. Carcasses were shipped to Texas A&M University where sides were randomly assigned two cutting procedures. Side A was fabricated into regular trimmed four lean cuts (RFLC). Side B was fabricated into bone-in and boneless four lean cuts (FLC) by progressively trimming s.c. fat to .64,.32, and 0 cm and the remainder separated into remaining fat, lean, bone, and skin to generate a boneless, 0 cm trimmed, seam fat removed (BLSFLC) endpoint. Remaining lean was separated into chemical fat and moisture (FFLFLC). During fabrication, carcass cross sections were photographed onto slide film, scanned, and then various fat and muscle deposits were measured with an image analysis program. Regression equations were produced using carcass cross section measurements to predict RFLC and bone-in and boneless FLC progressively trimmed to .64,.32, and 0 cm, BLSFLC, and FFLFLC. Twelfth rib fat depth 3/4 measure (TW5) and M. longissimus area (TW7) accounted for 81% of the variation in RFLC. Twelfth rib fat and muscle depth 1/2 distance measures (TW3 and TW4) produced R2 .79. Skinned, bone-in FLC progressively trimmed had R2 of .61,.68. and .73 when using TW5 and TW7. R2 dropped only .01 for each trim level when using TW3 and TW4. TW5 and TW7 had R2 =.55,.64,.70, and .78 and TW3 and TW4 were within .0 1 for every equation in predicting .64,.32, and 0 cm FLC and BSLFLC, respectively. TW3 and TW4 had R2 = .81 (.01 higher than TW5 and TW7) for predicting FFLFLC. Adding additional fat or muscle measurements to a fat and muscle measure over the M. longissimus at any location had minimal improvement in R2.
Harris, Shawn Dale (1995). Using fat and muscle measurements from different areas of the carcass in the prediction of yield of pork four lean cuts and primals as affected by cutting method and trim level. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -H377.