As use of distillers’ grains in cattle rations grows, one concern has been variability in the product, including, at times, high concentrations of sulfur in the feed. High levels of sulfur in the feed can impact animal health and performance, especially if an operation’s water supplies also contain high levels of sulfur. Researchers at Iowa State University recently conducted a trial to evaluate the effects of supplementing vitamin C in rations containing high levels of sulfur. Previous research indicated that vitamin C aids in clearance of sulfur metabolites from the body. The researchers fed 120 Angus-cross steers initially averaging 751 pounds, using three rations with varying levels of sulfur. Within each ration treatment, half of the groups received a vitamin C supplement and half did not. They fed the cattle 149 days and collected performance data throughout the feeding period and carcass data at slaughter. The researchers report that marbling score, backfat thickness, yield grade and hot carcass weight declined as dietary sulfur increased. However, the addition of vitamin C to the high-sulfur diet increased body fat, marbling scores and percentage of cattle grading Choice compared with cattle receiving the high-sulfur diet without vitamin C. The researchers conclude supplementation of vitamin C to cattle receiving the high-sulfur diet improved marbling scores. Although the exact mechanism for this improvement is unknown, they say it could be related to greater circulating vitamin C available for lipid metabolism in these cattle. Their report is published in the October 2013 issue of the Journal of Animal Science.