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