FACTORS AFFECTING THE OCCURRENCE OF DARK-CUTTING BEEF AND SELECTED CARCASS TRAITS IN FINISHED BEEF-CATTLE

A data set was used to determine how various factors affect the occurr ence of dark-cutting beef sind selected carcass traits in finished bee f cattle. Data were collected in 1989 and 1990 from one packer with pl ants located in Amarillo, TX; Boise, ID; Dakota City, NE; and Garden C ity, KS. The data set consisted of 3,659 lots consisting of 724,639 ca ttle. Compared with those at Boise and Dakota City, cattle slaughtered in Amarillo and Garden City had a higher incidence of dark cutters (1 .1 vs .3%; P < .01) and a lower quality grade (50 vs 64% Choice plus P rime; P < .01). The highest incidences of dark cutters occurred during August, September, and October (1.1 to 1.4%; P < .01), with incidence s of .4 to .7% during the other months. Carcass quality grade was high er during January, February, and March compared with May through Novem ber (60 to 62% Choice plus Prime vs 52 to 58%; P < .01). As the number of cattle in a lot increased, the incidence of dark cutters increased from .4 to 1.2% (P < .01), and quality grade declined from 62 to 52% Choice plus Prime (P < .01). As the mean weight of cattle in the lot i ncreased, the incidence of dark cutters declined from .94 to .6% (P < .01), and carcasses grading Choice plus Prime increased from 56 to 62% (P < .01). With cattle held over a weekend or holiday, (''carry cattl e'') the incidence of dark cutters increased from .8 to 1.6% (P < .01) . We conclude that packing plant location, month of the year, weight o f cattle, carry cattle, and number of cattle in a lot are most likely to influence the incidence of dark cutters and carcass quality traits.