How Does Frame Size, Forage Type, and Time-on-Pasture Alter Forage Finished Beef Quality?

Angus-cross steers (n=144; 364 ± 37.7 kg) were used in a 3 year study to assess the effects of frame size (medium or large), forage type(cool season pasture [PAST] or PAST and warm season annual [ANN]) and time-on-pasture (TOP; 151 or 205 d) on animal performance, carcass traits and beef composition in a forage-finishing system.Steers with large-frame size had greater (P<0.05) final live weight and hot carcass weight (HCW) compared to medium-frame steers. Extending the grazing time to 205 d also increased (P<0.05) live weight, HCW, and carcass fatness. Longer TOP increased (P<0.01) total lipid and total fatty acid content of the LM. Longer TOP increased (P<0.10) MUFA concentrations; in contrast, longer TOP decreased (P<0.05) n-6 polyunsaturated fatty acids (PUFA) and n-3 PUFA concentrations, which translated to lower (P<0.05) n-6:n-3 ratio. Warner-Bratzler shear force values were not affected (P>0.05) by frame size, forage type or TOP. In forage-finishing systems, steers that graze for longer TOP had greater fatness of the carcass and lower n-6 and n-3 PUFA concentrations. Large frame size increased live weight and HCW but had only minor impacts on composition.