Natural beef production and growth of Bonsmara steers stocked on rye and ryegrass pastures at humid and semiarid environments

Natural, organic, and grass-fed beef provides alternative products for consumers. During 2 consecutive yr, Bonsmara steers (n = 130) grazed winter pasture at 2 environments [semiarid, Uvalde (UVL), and humid, Overton (OVT)] and received pasture only (PAS) or pasture plus 0.8% BW/steer per day corn (SUPL) to quantify growth and carcass traits. Each year, 8 steers each from UVL and OVT were slaughtered off pasture and after a 90-d feedlot (FED) period. From initiation to termination (mid-May) of stocking on Maton rye (Secale cereale L.) plus TAM-90 annual ryegrass (Lolium multiflorum Lam.) at OVT and irrigated TAM-90 at UVL, ADG was greater (P < 0.01) for steers receiving SUPL (1.16 kg) compared with PAS (1.04 kg). During grazing, ADG was greater (P < 0.01) at OVT, 1.18 kg, compared with UVL at 1.03 kg. During FED, ADG was greater (P < 0.01) for steers previously on PAS (1.35 kg) compared with SUPL (1.18 kg). Pasture environment did not affect (P > 0.05) FED ADG. Growth in BW was linear (P < 0.05) during the pasture and FED period. The FED period increased (P < 0.01) HCW, LM area, marbling, QG, KPH, and adjusted fat thickness and reduced Warner-Bratzler shear force. Carcass traits were not affected (P > 0.05) by SUPL. Tenderness was enhanced (P < 0.05) for PAS and FED by electrical stimulation, blade tenderization, and days aging from 0, 14, and 28 d. Bonsmara steers had acceptable BW (500 kg) and carcass and tenderness traits when slaughtered off pasture or after FED and met industry considerations for a natural beef product.