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Estimates of beef carcass intermuscular fat
K R Kent1, G W Davis, C B Ramsey
1Dept. of Anim. Sci., Texas Tech University, Lubbock 79409.
Journal of Animal Science
|December 1, 1991
Summary
Intermuscular (IM) fat estimates reliably predict carcass chemical fat percentage and cutability. Visual estimation of IM fat and other traits on carcasses offers accurate predictions for beef quality.
Area of Science:
- Beef carcass evaluation and meat science.
Background:
- Accurate prediction of beef carcass composition (chemical fat percentage) and retail yield (cutability) is crucial for the beef industry.
- Traditional methods rely on USDA Yield Grade (YG) factors, but their predictive accuracy for specific fat components can be limited.
Purpose of the Study:
- To evaluate the effectiveness of intermuscular (IM) fat estimates and other visually assessed traits in predicting beef carcass chemical fat percentage and cutability.
- To compare the predictive power of IM fat estimates against traditional USDA YG factors.
Main Methods:
- Experienced evaluators assessed 158 carcasses for USDA YG, quality factors, subcutaneous (SC) fat, and IM fat indicators.
- Chemical composition, cutability, and total IM fat were determined on 40 selected sides.
- Correlation analyses and regression models were used to assess relationships between visual estimates and chemical composition/cutability.
Main Results:
- IM fat estimates at the 12th rib, rib-plate juncture, and 5th rib showed significant negative correlations with chemical fat percentage (r = -0.72, -0.70, -0.55).
- USDA YG factors explained 61% of the variation in chemical fat; substituting IM fat at the 12th rib for adjusted fat thickness (AFT) explained 60%.
- An equation using two IM fat estimates, marbling score, and longissimus muscle area explained 68% of chemical fat variation, and 65% of cutability variation.
Conclusions:
- Intermuscular fat estimates, particularly at the 12th rib, are reliable predictors of beef carcass chemical fat percentage and cutability.
- Visual estimation of IM fat and other carcass traits provides a practical and accurate method for predicting beef composition and yield on hot-fat trimmed carcasses.