FACTORS CONTRIBUTING TO THE INCIDENCE OF DARK CUTTING BEEF

The 1995 National Beef Quality Audit reported that dark cutting beef ( dark cutters) cost $6.08 per animal harvested in the United States. Fe edlot data were obtained over a 3-yr period from nine commercial feedy ards (15,439 pens of cattle; 2,672,223 total cattle). Feedyard, sex, i mplant treatment, days fi om final implant to harvest, maximum and min imum daily temperatures, and temperature fluctuations from 2 d before harvest to the day of harvest all contributed (P < .05) to the inciden ce of dark cutters. Heifers yielded a higher (P < .05) percentage of d ark cutters per pen and, when reimplanted a second time with an estrog enic implant, produced greater (P < .05) mean percentages of dark cutt ers per pen than heifers reimplanted with either androgens or combinat ion (androgen and estrogen) growth promotants. Furthermore, heifers pr oduced higher (P < .05) mean percentages of dark cutters per pen than steers during periods of hot (> 35 degrees C) weather 2 to 1 d before harvest. Steers, when treated with a combination (androgen and estroge n) implant when entering the feedyard and as a reimplant, produced hig her (P < .05) mean percentages of dark cutters per pen when compared t o other moderate growth-promoting implant strategies. When producers o pted to implant steers with estrogenic growth promotants, either as th e cattle entered the feedlot or as a final reimplant before harvest, t he occurrence of dark cutters was reduced from 9.2 per thousand cattle shipped to 2.0 and .5 per thousand cattle shipped, respectively. Prod ucers that reimplanted heifers before harvest with products that were not primarily estrogenic reduced the occurrence of dark cutters from 1 0.4/1,000 cattle shipped to 5.2/1,000 cattle shipped when androgen-bas ed growth promotants were used and to 3.5/1,000 cattle shipped when co mbination (androgen and estrogen) implants were administered. In addit ion to implant selection, those producers that held cattle on-feed ove r 100 d past reimplantation reduced the incidence of dark cutters per pen by an average of 38% among heifers and 69% among steers. By reduci ng the occurrence of dark cutters, there is an opportunity for beef pr oducers to realize large economic savings.