Doctor of PhilosophyDepartment of Animal Sciences and IndustryJames S. DrouillardFour studies evaluated effects of dry distillers grains with solubles (DDGS) containing high S concentrations on feedlot performance, ruminal fermentation, and diet digestibility by finishing cattle. Trial 1 used finishing steers fed diets based on steam-flaked corn (SFC) or dry-rolled corn (DRC), and containing 30% DDGS (DM) with 0.42% S (0.42S) or 0.65% S (0.65S). No interaction (P ≥ 0.15) between dietary S and grain processing occurred, but feeding 0.65S decreased DMI (P 0.05) or by the S × substrate interaction (P > 0.05). Study 4 evaluated cattle feedlot performance when exposed to DDGS containing high S levels, either continuously or intermittently. Treatments were chronic high S (CHS; 0.60% DM), chronic intermediate S (CIS; 0.50% DM), and sporadic intermediate S (SIS; oscillating from 0.40 or 0.60% S DM basis). Steers fed CHS had 11.2 and 6.1% less (P 0.10). These studies suggest that changes in cattle performance and digestibility associated with high S are primarily attributable to decreased DMI, but infrequent exposure to high levels is no more harmful than continuous exposure
