Location: Agroecosystems Management ResearchTitle: High sulfur content in corn dried distillers grains with solubles protects against oxidized lipids by increasing sulfur-containing antioxidants in nursery pigs Author
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2013
Publication Date: 6/1/2013
Publication URL: http://handle.nal.usda.gov/10113/57959
Citation: Song, R., Chen, C., Wang, L., Johnston, L.J., Kerr, B.J., Weber, T.E., Shurson, G.C. 2013. High sulfur content in corn dried distillers grains with solubles protects against oxidized lipids by increasing sulfur-containing antioxidants in nursery pigs. Journal of Animal Science. 91:2715-2728. Interpretive Summary: Oxidative damage of lipids in animal feed can negatively affect pig health and growth performance. It has been suggested that lipid peroxidation may occur during the production of corn dried distillers grains with solubles (DDGS). Corn oil, which is typically present at a concentration of approximately 10% in DDGS, contains high levels of polyunsaturated fatty acids which are vulnerable to lipid peroxidation. In addition, high temperatures used by ethanol plants to dry DDGS may also accelerate lipid peroxidation. On the otherhand, the total sulfur (S) content in corn DDGS can exceed 0.75%, due to the addition of sulfuric acid during the ethanol production process, with the S content in DDGS is elevated compared to corn grain, approximately 0.1% S. Sulfur is an essential component in many physiological functions of animals and is incorporated into amino acids, proteins, enzymes and micronutrients, including naturally occurring antioxidants in the body. Research results described in this report provides nutritionists at universities, feed companies, allied industries, and swine production facilities data that although feeding pigs a DDGS with high amounts of lipid peroxidation showed indications of metabolic stress, the concentrations of S-containing antioxidants in the body were elevated when fed DDGS suggesting that higher levels of dietary S may provide metabolic oxidative stress protection.
Technical Abstract: Some sources of corn dried distillers grains with solubles (DDGS) contain relatively high amounts of oxidized lipids produced from PUFA peroxidation during the production process. These oxidized lipids may negatively affect growth performance and metabolic oxidation status of pigs. The objective of this study was to understand the effects of feeding corn-soybean meal diets (CON) or diets containing 30% highly oxidized DDGS with one of 3 levels of vitamin E (a-tocopheryl acetate): none supplemented, NRC level (11 IU/kg), and 10X NRC level (110 IU/kg) on oxidative status of nursery pigs. The DDGS source used in this study contained the highest thiobarbituric acid reactive substances (TBARS) value, peroxide value, and total S content (5.2 ng/mg oil, 84.1 meq/kg oil, and 0.95%, respectively) among 30 other DDGS sources sampled (mean values = 1.8 ng/mg oil, 11.5 meq/kg oil, and 0.50%, respectively). Barrows (n = 54) were housed in pens and fed the experimental diets for 8 wk after weaning and transferred to individual metabolism cages for collection of feces, urine, blood, and liver samples. Total S content was higher in DDGS diets than CON (0.39 vs. 0.19%). Dietary inclusion of 30% DDGS improved apparent total tract digestibility of S (86.8 vs. 84.6%, P < 0.001) and S retained (P < 0.01) compared to CON. Although pigs were fed highly oxidized DDGS in this study, serum TBARS were similar between DDGS and CON treatments. There was no interaction between DDGS and dietary vitamin E concentration in serum TBARS. Serum a-tocopherol concentrations were higher in pigs fed DDGS diets compared with those fed CON when a-tocopheryl acetate was not provided or provided at NRC level (1.61 vs. 0.69 µg/mL). Pigs fed DDGS diets had higher serum concentrations of S-containing AA, particularly Met (P < 0.001) and taurine (P = 0.002), compared with those fed CON. Liver glutathione concentration was higher in pigs fed DDGS diets than CON (56.3 vs. 41.8 nmol/g). Dietary inclusion of DDGS (P < 0.001) and vitamin E (P = 0.03) increased serum enzyme activity of glutathione peroxidase. The elevated concentrations of S-containing antioxidants (Met, taurine, glutathione) in vivo may protect pigs against oxidative stress when feeding highly oxidized DDGS. Therefore, increasing levels of vitamin E in diets may not be necessary to protect pigs against metabolic oxidative stress when feeding high S and high oxidized DDGS.