EFFECTS OF NUTRITIONAL PLANES AND BREEDS ON INTRAMUSCULAR-LIPID DEPOSITION IN M-LONGISSIMUS-DORSI OF STEERS

The influences of nutritional planes and breeds on intramuscular-lipid (IML) deposition in M. longissimus dorsi were investigated by comparing the relationships between intramuscular lipid percentages (IMLP) in the muscle and side-carcass weight (SCW), carcass-fat percentage (CFP), and slaughter age (SA). Japanese Black (JB) and Japanese Shorthorn (JS) steers were fattened under two (medium-high and high) nutritional planes, which were different only in JB and when the adjusted IMLPs were compared on the basis of SCW or CFP. Breed effects on IML deposition were investigated by using three pure breeds and four crossbred-steer groups. The means of IMLPs in the muscle adjusted to three criteria were significantly different among breeds, the IMLPs of JB and their back-crosses being higher than those of JS and Charolais crosses. IML deposition in steers was highly dependent on the genetic potential of the breeds or bulls used.