Variations in the Quantity and Distribution of Lipid in the Bovine Longissimus Dorsi

Loins and ribs were obtained from the right side of 20 carcasses selected randomly over a 12-month period. The loin-rib units were classified into four groups based upon the amount of marbling exhibited at the 12-13th rib interface. One-quarter-inch-thick samples of longissimus dorsi were removed from a position opposite the mid-point of each vertebra, extending from the sixth thoracic to the fifth lumbar. Three judges subjectively evaluated the amount of visual marbling and its relative distribution at the anterior face of each section. Ether-extractable lipid was determined on each sample. The results revealed highly significant (P<.01) differences for marbling and ether-extractable lipid among marbling classifications. However, the uniformity of marbling distribution did not differ significantly among marbling groups. Highly significant (P<.01) differences for all variables were noted among anatomical positions within the longissimus dorsi. The extremities of the muscle contained a significantly higher level of intramuscular lipid than the medial section. The most uniform pattern of marbling distribution was observed at the 10-13th thoracic region and tended to decrease toward the muscle extremities.