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Sulfur from wet or dry distillers in feedlot cattle diets and the ruminal available sulfur concept
Three experiments were conducted to evaluate the effects of sulfur (S) concentrations from wet or dry distillers grains with solubles (DGS) and inclusions in cattle finishing diets on growth performance and ruminal metabolism; evaluate the effects of organic, inorganic and blend (wet DGS) sources of S when fed above ruminant S requirements on ruminal metabolism; and develop a concept and a laboratory procedure to measure ruminal S availability for reduction to H2S. Intake decreased for steers fed wet and dry DGS that was 1.16% S, and gain decreased when wet 1.16% S DGS increased in the diet compared to 0.82% S DGS. Improvement in G: F was observed for steers fed wet DGS compared to dry. Molar proportion of propionate declined when 1.16 compared to 0.82% S DGS was fed. Apparent total tract DMD was not affected by treatments. Greater ruminal H2S concentration for steers fed wet compared to dry DGS was observed, while 1.16% S DGS tended to have greater ruminal H2S concentration than 0.82% S. Calculated ruminally degradable S (RDS) intake was negatively related to ADG, but total S (TS) intake was not. Lower gain and greater H2S suggests S is more prone to be converted to H 2S in wet DGS diets. Steers fed inorganic S tended to have less DMI compared to those fed organic or blend sources of S. Calculated (RDS) and measured ruminal available S (RAS) intakes were greater for steers fed wet DGS, followed by inorganic, organic and least for corn control diets. Steers fed wet DGS and inorganic S sources spent more time eating compared to other treatments. Similar H2S were observed for steers fed inorganic and wet DGS S sources diets, which were greater than other treatments. Greater ruminal H2S at 8 than 13 h post feeding was observed only for steers fed organic sources of S and control diets. Ruminal H2S variation was better explained by RDS and RAS intakes compared to TS intake or ruminal pH variables. Acetate decreased, propionate molar proportions increased, and lower A: P ratio were observed for steers fed inorganic S compared to corn control diet. Using RDS or RAS was better to predict H2S than just total S. Ruminal H2S concentration may also modulate intake pattern. An in vitro procedure was developed to measure RAS. Greater S content from wet DGS has greater effect on cattle gain, intake and ruminal H2S than dry DGS.
Sarturi, Jhones Onorino, "Sulfur from wet or dry distillers in feedlot cattle diets and the ruminal available sulfur concept" (2012). ETD collection for University of Nebraska - Lincoln. AAI3503378.