Date of this Version
Journal of Animal Science (2013) 91: 1,454-1,467. DOI: 10.2527/jas2012-5914.
Angus-cross steers (n = 128; initial BW = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed before slaughter versus concentrate ﬁnishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) ﬁnishing treatments. At 40 d before harvest, MP steers were randomly divided into 3 forage species treatments: alfalfa (AL), pearl millet (PM), or mixed pasture (MP). Average daily BW gain was greater (P = 0.001) for CON than for forage-ﬁnished (FOR) steers during the early and overall ﬁnishing phase. During the late ﬁnishing phase when FOR steers were grazing difference forage species, ADG was greater (P = 0.03) for PM than MP or AL. Harvest weight and HCW were greater (P < 0.001) for CON than FOR due to the differences in animal performance. Total fat percentage of the 9th to 11th rib section was 46% less (P = 0.028) for FOR than CON due to reductions (P < 0.001) in the percentage of subcutaneous fat. Warner-Bratzler shear force (WBS) values at 14 d and 28 d of aging did not differ (P > 0.78) between CON and FOR and were not altered (P > 0.40) by forage species. Trained sensory panel juiciness, initial tenderness, and overall tenderness scores did not differ (P > 0.17) by ﬁnishing treatment or forage species. Beef ﬂavor intensity was greater (P < 0.001) for CON than FOR. Beef ﬂavor intensity was greater (P < 0.02) for AL and PM than MP. Off-ﬂavor intensity was greater (P < 0.001) for all forage-fed steaks, regard-less of forage species, than CON. Finishing on forages reduced (P = 0.003) total lipid content by 61% for the LM compared with CON ﬁnished cattle. Forage species grazed before harvest did not alter (P > 0.05) total lipid content of the LM. Oleic acid concentration and total MUFA of the LM were 21% and 22% less (P = 0.001) for FOR than CON. Concentrations of all individual [linolenic acid, eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosadexaenoic (DHA) acids] and total n-3 fatty acids were greater (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the concentration of linolenic acid compared with MP or PM. The ratio of n-6 to n-3 fatty acids was greater (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate ﬁnishing increases carcass weight with same time endpoints and accelerates deposition of MUFA in comparison with FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d before slaughter did not alter beef tenderness but FOR had greater off-ﬂavors according to both trained and descriptive sensory panelists.