title: Impact of source of sulfur on ruminal hydrogen sulfide and logic for the ruminal available sulfur for reduction concept.
abstract: Effects of organic and inorganic sources of S on intake, intake pattern, ruminal pH, VFA profile, and ruminal H2S gas concentration ([H2S]) were evaluated, which lead to development of a procedure to measure ruminal S availability for reduction [ruminal available S (RAS)] as well as compare with an estimated number [adjusted ruminal protein S (ARPS)]. Ruminally cannulated crossbred beef steers (n = 5; BW = 548 ± 46 kg) were assigned to 1 of 5 diets in a 5×5 Latin square design and fed ad libitum in five 21-d periods. Steers were fed a dry-rolled corn diet (CON), inorganic S source (ammonium sulfate; INORG), organic S source (corn gluten meal) fed at 9.8 (ORG-L) or 23% of diet DM (ORG-H), or wet distillers grains with solubles (WDGS) fed at 50% of diet DM. For the laboratory procedure, individual ingredients were incubated with ruminal fluid from heifers fed 60% corn-based diets (n = 2) and McDougall's buffer. Bottles were cooled in ice, centrifuged, and decanted, and the precipitate was analyzed for S. Steers fed INORG tended (P = 0.12) to consume 12% less DM. Total S intake was greater (P < 0.01) for steers fed WDGS (60 g/d) followed by ORG-H, and the lowest S intake was observed for CON (22 g/d). Intakes of ARPS and RAS were greater (P < 0.01) for steers fed WDGS followed by INORG, ORG-H, ORG-L, and CON diets. Steers fed WDGS and INORG diets spent 13% more time eating (P < 0.01) compared with other treatments. There was an interaction (P = 0.05) between treatment and time for ruminal [H2S]. Similar [H2S] were observed for steers fed INORG and WDGS diets (P = 0.28), which were greater (P ≤ 0.05) than other treatments. Greater ruminal [H2S] at 8 h compared with 13 h postfeeding was observed for steers fed ORG-H, ORG-L, and CON diets (P ≤ 0.04). Nearly 65% of ruminal [H2S] variation was explained (linear; P < 0.01) by RAS intake, ARPS explained 58% (linear; P < 0.01), S intake explained 29% (quadratic; P < 0.01), average ruminal pH explained 12% (linear; P < 0.01), and area below ruminal pH 5.6 explained 16% (linear, P < 0.01) of the variation. A 6% decrease in acetate (P = 0.01), 20% increase in propionate molar proportions (P = 0.02), and a lower acetate:proprionate ratio (P = 0.02) were observed for steers fed INORG compared with CON diet. The RAS concept is important for predicting ruminal [H2S] rather than just total S in the diet. Coefficients of RAS for individual ingredients can be predicted using in vitro procedures. Ruminal [H2S] may also modulate intake pattern.
authors: Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583-0908, USA.
authors: J O
authors: JO
authors: Sarturi
authors: G E
authors: GE
authors: Erickson
authors: T J
authors: TJ
authors: Klopfenstein
authors: K M
authors: KM
authors: Rolfe
authors: C D
authors: CD
authors: Buckner
authors: M K
authors: MK
authors: Luebbe
mesh_terms: D000821:Animal Feed / Q000032:analysis; D053180:Animal Nutrition Sciences / Q000379:methods; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects*; D006862:Hydrogen Sulfide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D011897:Random Allocation; D012417:Rumen / Q000737:chemistry*; D013455:Sulfur / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D013455:Sulfur; D006862:Hydrogen Sulfide