Effect of feeding various dried distillers grains plus solubles on beef meat quality

Abstract

Two studies were designed to investigate the effect of feeding crossbred beef steers a standard barley-based control diet or substituting wheat, corn, or wheat/corn (40% dry matter basis) dried distillers grains plus solubles (DDGS) on the resulting meat quality. The first study investigated the effect of diet on the quality of the longissimus muscle. It was observed that diet did not have an effect on meat composition, pH, drip loss or shear values; however, diet did have an effect on colour attributes, with steaks obtained from steers fed a DDGS diet losing redness faster over time and having a less desirable retail appearance than steaks obtained from steers fed the control diet (P<0.001). Differences (P<0.05) were also observed in both the subcutaneous and intramuscular fatty acid profiles, with steers fed corn DDGS having elevated levels of trans-monounsaturated fatty acids, and steers fed a DDGS diet having elevated levels of branched-chain fatty acids and conjugated linoleic acid. The fatty acid composition of cattle fed a DDGS diet also had higher (P<0.05) concentrations of polyunsaturated fatty acids, which resulted in a less desirable n-6 to n-3 ratio. Despite the fact that fat obtained from steers fed a DDGS diet had elevated levels of total unsaturated fatty acids when compared to steers fed the control diet, no differences were observed in regards to the oxidative stability of raw or cooked meat as determined by thiobarbituric acid reactive substances. The second study investigated the effect of diet on the quality of raw and pre-cooked semimembranosus roasts injected with a salt/phosphate brine. No dietary effects were observed in meat quality, processing attributes, or shear values of the non-injected SM roasts, while roasts prepared from the semimembranosus of animals fed corn DDGS had the lowest brine pickup and the highest shear values. Raw non-injected meat from steers fed a DDGS diet was less oxidatively stable than meat obtained from steers fed a control diet. Oxidative changes due to diet were mitigated in the cooked injected roasts due to the chelating effect of phosphate, which improved overall oxidative stability. Similarly, oxidation levels in the pre-cooked SM roasts remained below levels where rancidity is normally detected over 56 days of refrigerated storage at 4°C. Overall, replacing barley grain with 40% wheat, corn, or wheat/corn DDGS did not have a profound impact on meat quality attributes of raw or cooked meat.