Animal Science Department


Date of this Version



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professor Chris R. Calkins. Lincoln, NE: August 2011

Copyright 2011 Asia Haack


Feeding distillers grains to cattle decreases shelf life stability of retail displayed steaks due to the increased polyunsaturated fatty acid (PUFAs) content. High levels of PUFAs cause rapid oxidation of the fats in meat. To improve shelf life, a low-fat distillers grain ration, without solubles (LFWDG; 4.72% fat), was compared to a traditional diet containing wet distillers grains plus solubles (TWDGS; 6.91% fat) and a corn-based control diet (Corn; 3.64% fat). Strip loins (M. longissimus lumborum) from 45 USDA Choice steers (15 per dietary treatment) were selected to determine the effects of diet on fatty acid profile, fat composition, oxidation, color changes during retail display, flavor and tenderness. After 4 days of simulated retail display, samples from cattle fed LFWDG had significantly (P < 0.05) more oxidation than TWDGS or controls as measured by objective and subjective color scores. By day five of simulated retail display, steaks from cattle fed LFWDG were less red in color (lower a*) and had more visual discoloration than the other steaks (P < 0.01). The L* and b* values were not significantly different. Steaks from LFWDG were less tender (P ≤ 0.0006) and had a more distinct off-flavor (P ≤ 0.02) after display than TWDGS. Meat from LFWDG had about 10% more PUFAs than TWDGS (4.86 vs. 4.46, respectively; P = 0.08). These data suggest fatty acids contained within the distillers grains are not biohydrogenated during digestion, while fatty acids in the soluble fraction are more readily hydrogenated in the rumen. Consequently, diets formulated with LFWDG tend to compromise meat quality after extended retail display.

Advisor: Chris R. Calkins