| Abstrakt: |
Three-hundred and fifty-nine pork carcasses varying widely in muscling fatness were selected from two commercial packing plants. Measurements were made of carcass length, fat depth (3/4 measure-10th rib), longissimusmuscle area, average backfat thickness, USDA muscling score and carcass weight. These independent variables were considered to be easily obtainable on the ribbed (between the 10th and 11th ribs) but otherwise intact carcass. The four lean cuts were sequentially fabricated and processed into separable lean, fat and bone. Multiple regression equations were developed to predict percentage of lean in the four lean cuts (L4LC) and to predict muscle to bone ratio in the four lean cuts (M:B). Results indicated that: (1) M:B differed widely among pork carcasses (from 2.89 to 5.49) and was distributed normally; (2) M:B was important in predicting L4LC in a population of carcasses ranging in backfat from 2.29 to 3.28 cm but did not add significantly to predictive accuracy in a population of carcasses with a backfat range of 2.29 to 5.33 cm; (3) the best two-variable equation for predicting L4LC included fat depth and longissimusmuscle area (R2= .87), and the best three-variable equation for predicting L4LC included M:B, fat depth and longissimusmuscle area (R2=.89); (4) the best two-variable equation for predicting M:B included longissimusmuscle area and USDA muscling score (R2=.54), and the best three-variable equation for predicting M:B included longissimusmuscle area, USDA muscling score and carcass length (R2= .55); (5) USDA muscling scores and longissimusmuscle area were significantly associated with M:B (r = .64 and .69, respectively); (6) no prediction equation could account for more than 60% of the observed variability in M:B, and (7) the addition of actual M:B to fat depth and longissimusmuscle area increased the accuracy of estimating L4LC by only 2%, suggesting that the value of estimated M:B probably would not be sufficient to warrant its inclusion in prediction equations for estimating leanness of ribbed carcasses. |
