Alternative Beef Finishing Strategies: Effects on Animal Performance, Retail Shelf Life, Sensory, Fatty Acid Profile and Lipid Stability

Abstract

The effect of supplemental concentrate levels to steers finished on winter annual ryegrass (Lolium multiflorum Lam.) or full concentrate (GRAIN) was studied. Initial color, fatty acid profile, retail shelf-life, lipid stability and Vitamin E levels were determined. Treatment did not effect initial lean L*, a*, or b* values (P > 0.05). However, treatment did effect subcutaneous fat L* (P = 0.01) and b* (P = 0.002) values. All ryegrass treatments had higher b* values when compared to GRAIN. Total conjugated linoleic acid (CLA) was lower (P = 0.04) in GRAIN than 0.0% supplementation. Total, saturated, monounsaturated, poly-unsaturated, n-6, and PUFA:SFA FA levels were not affected by treatment (P = 0.13, 0.15, 0.15, 0.23, 0.06, and 0.56, respectively). Proportion of n-3 FA (P = 0.02) was highest in the 0.0% treatment. The ratio of n-6:n-3 FA (P < 0.001) generally increased with elevated supplementation. Visual measures of lean uniformity generally increased with elevated forage in the diet (P = 0.001). Steaks from GRAIN cattle had lower a* (P = 0.001) and higher metmyoglobin (P = 0.001), than all other treatments. Measures of lean discoloration generally decreased in proportion to increased forage in the diet. LS stability increased with amount of forage in the diet (P = 0.04) and vitamin E levels in longissimus muscle samples were not affected by treatment diet (P = 0.54). The effect of supplemental Tasco meal (Ascophyllum nodosum) and soy hull pellets in a winter annual ryegrass based finishing diet was also examined. Forage and animal performance, carcass and initial color, sensory and shear attributes, fatty acid profile and retail shelf-life and lipid stability analyzes were performed. There were no affects (P > 0.05) of Tasco treatment on any of the evaluated forage, animal performance, carcass, initial color, sensory, shear, fatty acid profile, retail shelf-life and lipid stability factors. However, supplementing steers did increase (P = 0.02) overall dressing percentage regardless of Tasco treatment. Initial subcutaneous fat b* values tended to increase (indicating a more yellow color) for cattle supplemented with Tasco and soy hull pellets (P = 0.08) over all other forage-finishing diet treatments. Additionally, n-3 polyunsaturated fatty acids tended (P = 0.10) to increase for cattle supplemented solely with Tasco on winter annual ryegrass. The ratio of n-6:n-3 tended to decrease in cattle not supplemented with soy hull pellets (P = 0.06). Fatty acid and cook-loss levels did increase (P < 0.05) with extended days of postmortem ageing, regardless of Tasco or soy hull pellet treatment. Off-flavor scores increased (P < 0.05) with extended steak exposure to simulate retail display conditions and postmortem ageing treatment.