Effect of dietary distillers dried grains with solubles on indicators of oxidative stress and immune function in growing pigs

Abstract

Distillers dried grains with solubles (DDGS) from corn contain relatively large amounts of polyunsaturated fatty acids and some yeast components, which may increase oxidative stress and alter immune function, respectively, when fed to pigs. Therefore, indicators of oxidative stress and immune status were determined in pigs (n=24; initial BW 103.8±5.9kg) fed corn soybean meal-based diets or diets containing 35% DDGS for 38days. On day 38, blood samples were collected for plasma and erythrocyte glutathione, 4-hydroxynonenal (4-HNE) protein adduct, nitrite, oxygen radical absorbance capacity, and thiobarbituric acid reactive substances (TBARS) analyses. Peripheral blood mononuclear cells were isolated, and lysates were analyzed for 4-HNE, superoxide dismutase-1 and glutathione-s-transferase-4. Fresh urine was collected and analyzed for F2-isoprostane and TBARS. Plasma immunoglobulin A (IgA), IgG, and fecal IgA were determined, and on day 39, pigs fed each diet were injected intramuscularly with saline (n=6 pigs per diet) or Escherichia coli lipopolysaccharide (LPS; n=6 pigs per diet) and plasma cytokines and metabolites were determined at 4h post LPS injection. There were no differences in basal circulating indicators of oxidative stress between dietary treatment groups, but urinary TBARS were increased (p<0.05) in pigs fed DDGS as compared to pigs fed the control diet. Plasma concentrations of IgA and IgG were increased (p<0.05) in DDGS-fed pigs versus pigs on the control diet. In pigs fed DDGS, body temperatures were greater (p<0.05) at 4h post-LPS than pigs fed corn–soybean meal diets, but LPS-induced alterations of plasma cytokines or metabolites were not different between dietary treatment groups. In conclusion, feeding DDGS does not alter circulating oxidative stress indicators, but increases urinary TBARS. Furthermore, dietary DDGS enhance humoral immunity, but in general do not alter the systemic response to LPS.