CASE STUDY: Carcass characteristics of Angus steers finished on grass or grain diets at similar quality grades

Research comparing grain- and grass-finished steers usually compares steers at the same chronological age. Because fat depots develop slowly in grass-finished steers, results are biased for greater fat and muscle development in grain-finished steers. The purpose of this study was to compare carcass characteristics and profitability between grain- and grass-finished steers at a minimum level of fat development (high-Select). Twenty-nine Angus steers (15 mo of age) with similar initial traits were finished on irrigated annual ryegrass (Lolium multiflorum) and white clover (Trifolium repens) pasture (CP = 14.3%, ME = 2.58 Mcal/kg of DM) for 303 d (n = 15) on average or finished on an 80% cracked-corn (CP = 9.70%, ME = 3.07 Mcal/kg of DM) diet for 168 d (n = 14). At slaughter, grain-finished steers exhibited greater final BW, ADG, ultrasound i.m. fat percentage, ultrasound backfat thickness, HCW, DP, KPH, calculated LM area, and retail yield than did grass-finished steers (P < 0.0001). Percent muscling was smaller, but percent fat was greater for grain-finished compared with grass-finished steers (P ≤ 0.0010). Taste-panel judges did not detect differences (P ≥ 0.14) in juiciness, flavor intensity, flavor quality, or overall palatability. Furthermore, there was no difference in shear force or cooking loss between steaks from grass-or grain-finished steers. There was a difference in profitability, if a premium of 8% for grass-finished beef was considered (P = 0.010). Therefore, both groups had similar sensory qualities and profitability per steer, but grain-finished cattle yielded more muscle and fat.