Date of this Version
Journal of Animal Science, August 2, 2012; doi: 10.2527/jas.2010-3240
Wet distillers grains contain approximately 65% moisture. A partially dried product (modified distillers grains plus solubles; MDGS) contains about 50% moisture. However, both have similar nutrient composition on a dry matter basis. The objective of this study was to investigate the effects of finishing diets varying in concentration of MDGS on marbling attributes, proximate composition, and fatty acid profile of beef. Yearling steers (n = 268) were randomly allotted to 36 pens which were assigned randomly to 0, 10, 20, 30, 40 and 50% MDGS (DM basis) and fed for 176 d prior harvest. Forty-eight h postmortem marbling score, marbling texture, and marbling distribution were assessed by a USDA grader and one ribeye slice (longissimus thoracis) 7 mm thick was collected from each carcass for proximate and fatty acid analysis. Treatments did not significantly alter marbling score or marbling distribution (P ≤ 0.05). USDA Choice slices had coarser marbling texture when compared to USDA Select. Although dietary treatment affected marbling texture no consistent pattern was evident. Diets did not influence fat content, moisture, or ash of the ribeye (P ≥ 0.05). For treatments 0, 10, 30, 40 and 50% there were positive linear relationships between marbling score and fat percentage in the ribeye (P ≤ 0.05) and all slopes were similar (P = 0.45). Feeding MDGS linearly increased stearic, linoelaidic, linoleic, linolenic, PUFA and n-6 fatty acids. As levels of MDGS increased, linear decreases were observed in all n- 7 fatty acids and cubic relationships were detected for the 18:1 trans isomers (trans-6-8-Octadecenoic acid, 6-8t, elaidic acid, 9t, trans-10-Octadecenoic acid, 10t, and trans vaccenic, 11t). No effects were observed for saturated fatty acids containing 6 to 14 carbons. Feeding MDGS resulted in increased PUFA, trans, and Omega 6 fatty acids, minimal effects on marbling texture, and no effects on the relationship of marbling to intramuscular fat content relationship.