Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract only
Publication Acceptance Date: 5/10/2007
Publication Date: 7/9/2007
Citation: Brown, K.R., Cox, R.B., Anderson, G.A., Rentfrow, G.K., Bush, L.P., Strickland, J.R. 2007. Neotyphodium Coenophialum Exposure Reduces Carcass Mass and Ribeye Area, but not Meat Quality of Growing Steers Grazing High Versus Low Endophyte Infected Forages. Journal of Animal Science. 85:Suppl 1. pg 12 (Abstract #M26). Interpretive Summary:
Technical Abstract: Steers that graze toxic endophyte-infected tall fescue before undergoing a finishing feed regimen experience decreased growth during finishing and carcass characteristics at slaughter. The potential effects of consumption of toxic endophyte-infected tall fescue on growth, carcass quality, and postmortem parameters of growing Angus steers slaughtered off of pasture were examined. Steers were randomly allotted by weight to either a low-endophyte (LE; 6.8 % infection) mixed grass fescue pasture (n = 9; BW = 266 ± 10.9 kg; 5.7 ha) or a high endophyte (HE; 62.8 % infection) fescue pasture (n = 10; BW = 267 ± 14.5 kg; 5.7 ha) for at least 85 d. Shrunk BW was measured at d 0, 36, 57 and 85, and carcass parameters taken at slaughter (d 89, 91, 98, 103, or 105). ADG was greater (P < 0.01) for LE than for HE (0.40 vs -0.05 kg, respectively) from d 0 to 36, but no treatment difference was observed for ADG or BW for the overall 85 d period. However, BW at slaughter (P < 0.05; 338 vs 313 kg), hot carcass BW (P < 0.01; 172 vs 148 kg), and dressing percentage (P < 0.01) of LE steers were greater than for HE. Although 12th rib backfat thickness did not differ between LE and HE, the REA of LE steers was greater (P < 0.01; 60.3 vs 51.7 cm2). No differences in pH, a*, b*, or shear force of REA steaks were observed between LE and HE on d 7, 14, or 21 postmortem. Although no treatment effects were observed for hue angle and chroma values, REA steak L* values of LE steers were 1.3 to 2.0 units higher (P < 0.04) than for HE at d 7, 14, and 21. These results indicate that steers grazing fescue pastures with a high percentage of endophyte infection have reduced carcass mass and REA, but not indices of meat quality after 85–105 d of exposure.