Abstract
Relationship of beef carcass compositon and its conformation was investigated using 122 steer carcasses from 2 strains of Japanese Black (35 and 31), Holstein (16), Japanese Shorthorn (20) and Crossbred between Japanese Black (75%) and Holstein (25%) (20). Steers were slaughtered at four live weight stages from about 350kg to the upper limit of 570 to 738kg according to the matureness of breeds. Carcass conformation was measured on 23 locations concerning length, girth, thickness and width of left side carcass. Carcass tissues composition was determined by dissection method. Relationship between carcass conformation and carcass tissue growth was analyzed by a multiple regression method. Twenty three carcass measurements and four principal components on carcass conformation which were taken out by a principal component analysis on carcass measurements were used as dependant variables and each carcass tissue weights were used as independant variables. Relationship between the first principal component (carcass size factor) and the amounts of muscle, fat and bone in carcass was highly significant. Secondary principal component (thinness of carcass) related positively to the amount of bone and negatively to the amounts of muscle and fat. Carcass length was highly related to the growth of bone and early maturity trait relative to the thickness and girth of carcass which were highly correlated to the muscle and fat growth. Differences of carcass conformation between breeds were seemed to be originated not only to the differences of matureness among breeds, but also the differences of growth patterns of tissues in specified carcass portions and consequently tissue distribution among breeds.
