D. M. Stiffler

Characterization of cutability and palatability attributes among different slaughter groups of beef cattle

Fifteen slaughter cattle from five groups (Charolais crossbred bulls, Brahman crossbred steers, Holstein steers, mixed-Exotic crossbred heifers and Hereford-Angus crossbred steers) were randomly selected from a commercial feedlot. Time-on-feed was 108, 114, 102, 108 and 145 days for the aforementioned groups, respectively. Carcasses from Charolais crossbred bulls had the highest percentage yield of chuck and round, but the lowest percentage yield of loin; hereford-Angus crossbred steers had the lowest percentage yield of round and Holstein steers had the lowest percentage yield of rib. Carcasses from Charolais crossbred bulls had the highest percentage yield of major retail-ready subprimals and lean trim, Hereford-Angus crossbred steers had the highest percentage yield of fat trim and Holstein steers had the highest percentage yield of bone from the major wholesale cuts. Mean percentage yields of closely trimmed, boneless retail cuts were highest for carcasses from the bulls and lowest for carcasses from the Hereford-Angus steers. Although Holstein steer carcasses had less fat trim than Brahman-crossbred steers mixed-Exotic heifers, this advantage was largely offset by their higher percentage of bone. Loin steaks from carcasses of Charolais crossbred bulls, Holstein, mixed-Exotic heifers were comparable (P > 0·05)with those of Hereford-Angus steers for shear force and sensory panel tenderness ratings. However, loin steaks from carcasses of Brahman-crossbred steers had significantly higher (P < 0·05) shear force values (least tender) and lower (P < 0·05) tenderness and overall palatability ratings. No diffeerences (P > 0·05) were found for flavor desirability of loin steaks among any of the groups. For bottom round steaks, Hereford-Angus steers received the highest palatability ratings while those from Holstein steers received the lowest palatability ratings.

Storage and display characteristics of electrically stimulated, hot-boned and nonstimulated, cold-boned beef

One side, randomly selected from each of 33 carcasses from forage-fed steers, was electrically stimulated within 30 min of exsanguination and hot-bonded (ESHB). Opposite sides were not electrically stimulated and were cold-boned (NESCB) following a 24 h chill (0°C). From 17 ESHB sides, portions of the longissimus dorsi (LD) and semimembranosus (SM) muscles were removed and immediately vacuum packaged. LD and SM muscles were removed from the remaining 16 ESHB sides, wrapped in polyvinyl chloride film, chilled (0°C) for 22 h and then vacuum packaged. LD and SM muscles from NESCB sides (n = 33) were removed and the vacuum packed at 24 h post mortem. Whole muscle characteristics were evaluated initially and after storage periods of 7, 14 or 21 days and steaks were displayesd for 5 years thereafter. Neither hot versus cold-boning nor storage for 21 days affected retail display characteristics of LD and SM steaks (P > 0·05). As retail display time increased, retail lean color, fat color and overall appearance scores decreased.

Palatability characteristics of loin steaks from Charolais crossbred bulls and steers.

Loins from 1 2 - blood or 3 4 - to 7 8 - blood Charolais bulls (n = 60) and steers (n = 64) were obtained at 24 h post mortem from electrically stimulated sides and, at 12 days post mortem, steaks were removed and frozen. Shear force values were higher (P < 0·001) and sensory panel evaluations of tenderness and overall palatability were lower (P < 0·001) for steaks from bulls than from steers. No differences (P > 0·05) in connective tissue amount or off-flavour were detected for steaks from bulls versus steers. Significant correlations between carcass secondary sex characteristics and sensory panel evaluations of tenderness were noted, but the coefficients were not of a magnitude to be considered predictive of tenderness.

Cutability comparisons of Charolais crossbred bulls and steers

Seventy-two sides (eighteen sides from each sex-breed group) from carcasses of half-blood or three-quarters-to-seven-eighths-blood Charolais bulls or steers of known history and age, handled alike from weaning to slaughter, were used. All cattle were fed in a commercial feedlot (average days-on-feed was 186) and slaughtered in a commercial packing plant. Comparisons were made for percentages of (1) untrimmed wholesale cuts, (2) partially boneless subprimals (trimmed of fat in excess of 1·9 cm), (3) partially boneless retail-ready cuts (trimmed of fat in excess of 0·95 cm) and (4) boneless retail-ready cuts (trimmed of fat in excess of 0·95 cm). Bulls had higher percentages than steers of chuck and round at all stages of trim. Steers had higher percentages of untrimmed, wholesale loin and partially boneless shortloin (1·9 cm fat) than bulls but steer percentages of shortloin cuts trimmed to 0·95 cm of fat did not differ from those of bulls. Bulls averaged 48·05%, while steers averaged 45·45%, major boneless, closely trimmed retail-ready cuts. After the lean trim was adjusted to 25% chemical fat, bulls had 27·70% lean trim and 5·65% fat trim while steers had 24·30% lean trim and 12·15% fat trim. No difference in the percentage of retail-ready cuts was attributable to breed; however, the three-quarters-to-seven-eighths-blood Charolais group had a lower percentage of standardized fat trim and a slightly higher percentage of bone than the half-blood group.