Carcass Characteristics of Steers from Two Genetic Types of Angus Cattle Developed on Either Forage or Feedlot Regimens

Abstract

The objective of this study was to compare carcass characteristics of a sample of small, early-maturing Angus steers (Angus-I) to those of a sample of modern Angus steers (Angus-II). Steers were developed as contemporaries on either pasture (n = 68) or grain diet (n = 66) regimens over 8yr (1987 to 1994). Within each regimen, carcass data were analyzed using a model that included terms for year, genetic type, year × genetic type interaction, and age of steer as a covariate. The Angus-II steers had heavier (P<0.05) live weight, hot carcass weight, and chilled carcass weight than Angus-I steers (for pasture: 374 ± 5 vs 338 ± 6, 217 ± 3 vs 195 ± 4, and 210 ± 3 vs 191 ± 4 kg, respectively; and for feedlot: 428 ± 6 vs 365 ± 10, 261 ± 4 vs 222 ± 6, and 255 ± 4 vs 218 ± 6 kg, respectively). Longissimus muscle area, fat thickness, marbling, and yield grade were higher (P<0.05) for Angus-II than for Angus-I feedlot-developed steers but did not differ for pasture-developed steers. Angus-II steers had more total retail cuts on a weight basis than Angus-I steers for both regimens, whereas total retail cuts as a percentage of chilled carcass weight differed for pasture-developed steers (73 vs 71%; P<0.05) but not for feedlot-developed steers. Total lean product and bone in the right side of the carcass was higher (P<0.05) for Angus-II than for Angus-I for both regimens. Total fat (kilograms) was higher (P<0.05) for Angus-II than for Angus-I feedlot-developed steers but did not differ for the pasture-developed steers. When expressed as a percentage of the chilled right side, total fat was lower and total bone was higher for Angus-II (P<0.05) pasture-developed steers, whereas no differences were seen in percentage total lean or fat for feedlot-developed steers. Pasture-developed Angus-II steers had a higher (P<0.05) percentage of foreshank, chuck, round, and sirloin, and a lower percentage of plate, when expressed as a percentage of chilled carcass weight than pasture-developed Angus-I steers. For both feedlot- and pasture-developed steers, some differences in carcass characteristics and composition existed between the two types of Angus cattle. Beef with acceptable quality and palatability traits can be produced with an all-forage diet.