Criteria of belly bacon desirability. III. Within-belly variance in chemical and physical characteristics

Within-belly variation (four cross-section rashers per belly) was substantially greater than the variation between bellies (n = 730) for the physical dimensions of width of rasher and depth at maximum and minimum points. Ratios among these variables has large coefficients of variation and their between-belly components of variance were negative. Correlations among measurements, both within and between rashers were small, indicating limited potential for predicting variance in any one physical dimension from knowledge of another. However, variation in width and depth measurements was associated with variation in the carcass measurements of backfat and carcass weight. Regression analyses identified carcass backfat as an important contributor to within-rasher variance in composition traits (percent fat, percent protein, lean ratios, photo grade). Accuracy of prediction was improved by enlarging the regression equation to include specific gravity of the belly, but was not influenced by either sex or weight of carcass. Variance component analyses identified a larger within-belly component for percent fat than for percent protein and, for both traits, the within-belly component was greater for castrates than for gilts. Individual pig differences contributed little to the between-belly variance for percent fat after consideration of backfat and weight. It was concluded that composition is the only aspect of belly bacon desirability that is amenable to prediction from measurements made on the carcass or the belly, that potential fat–lean ratio can be predicted from knowledge of carcass backfat, and that the accuracy of estimation can be further improved by adding specific gravity to the estimation equation.