EFFECT OF BIOLOGICAL TYPE OF CATTLE ON THE INCIDENCE OF THE DARK, FIRM, AND DRY CONDITION IN THE LONGISSIMUS MUSCLE

The objectives of this experiment were to characterize longissimus mus cle color, texture, and firmness for beef carcasses of diverse biologi cal types and to determine the genetic parameters of lean color, textu re, and firmness. The carcasses (n = 3,641) used in this experiment we re from steers produced by mating Angus, Brahman, Braunvieh, Charolais , Chianina, Galloway, Gelbvieh, Hereford, Jersey, Limousin, Longhorn, Maine Anjou, Nellore, Piedmontese, Pinzgauer, Red Poll, Sahiwal, Saler s, Shorthorn, Simmental, South Devon, and Tarentaise sires to Hereford and Angus dams. Steers were fed a corn-corn silage diet from weaning until slaughter at 356 to 575 d of age. Steers were slaughtered at com mercial packing plants and longissimus muscle color, texture, and firm ness were scored by trained carcass evaluators. Sire line least square s means for lean color, texture, and firmness ranged approximately one unit on a 7-point scale. Chianina crosses had darker-colored lean tha n all breed groups except Tarentaise and Simmental crosses (P < .05). Moreover, a higher percentage (P < .05) of Chianina crosses than of al l other breed groups had unacceptably dark-colored (''dark red'' or da rker) lean. Bos indicus sire lines were not different from Bos taurus sire lines in frequency of carcasses with unacceptably dark-colored le an. However, Bos indicus crosses were more likely to be scored ''very light cherry-red.'' Lean color and texture were lowly heritable, where as lean firmness was moderately heritable. Thus, this experiment demon strated that there is genetic variation in the incidence of the DFD co ndition; however, genetic variation was small relative to environmenta l variation.