title: Sulfur and nitrogen metabolism in the bovine fed different forms of supplemental sulfur.
abstract: Twelve growing Angus heifers averaging 282 kg in weight were fed a tall fescue hay-based diet in a completely randomized design experiment to determine sulfur (S) and nitrogen (N) metabolism and bioavailability of different forms of supplemental S:elemental S (E), sodium sulfate (SU) and DL-methionine (M). The study included a 72-h adaptation phase that was followed immediately by a 5-d retention phase. Control (C) heifers were fed a ground fescue hay diet twice daily throughout the study. Supplementation with .15% S from E, SU or M to the basal diet began at h 0. Differences in total blood S, plasma S and ruminal NH3 N were dependent on sampling time in the 72-h adaptation phase. Urinary S excretion during 0 to 72 h was greater for S-supplemented calves than for C. Mean molar proportions of acetate, butyrate, isobutyrate and valerate were affected by form of S supplementation. No treatment differences (P greater than .10) were noted in total VFA concentrations. Sulfur supplementation increased daily urinary sulfate (P less than .01), total urinary S (P less than .01) and fecal S (P less than .01) excretion during the retention phase. Methionine and SU heifers had the greatest urinary S losses, and fecal S was highest for E (P less than .01). No differences (P greater than .10) in DM digestion occurred among treatments. N retention (g/d) and N retention as a percentage of intake averaged 5.9, 8.5; 13.2, 18.7; 13.8, 20.5; and 11.3, 19.2, respectively, for C, E, SU and M. Sulfur retention (g/d) was increased (P less than .10) by S supplementation. Sulfur supplementation of a basal fescue hay diet increased S retention transitorily, although much of the added S was lost through excretory routes. Supplementing S as E, SU or M appeared to be equally beneficial, despite differences in route and extent of S excretion among the three S sources.
authors.affiliation: Dept. of Anim. Sci., University of Kentucky, Lexington 40546-0215.
authors.forename: M J
authors.initials: MJ
authors.lastname: Fron
authors.forename: J A
authors.initials: JA
authors.lastname: Boling
authors.forename: L P
authors.initials: LP
authors.lastname: Bush
authors.forename: K A
authors.initials: KA
authors.lastname: Dawson
mesh_terms: D000222:Adaptation, Physiological; D000821:Animal Feed; D000818:Animals; D001682:Biological Availability; D001806:Blood Urea Nitrogen; D002417:Cattle / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D008715:Methionine / Q000493:pharmacokinetics; D009584:Nitrogen / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism; D013431:Sulfates / Q000493:pharmacokinetics; D013455:Sulfur / Q000378:metabolism* / Q000493:pharmacokinetics / Q000652:urine
chemical_list: D005232:Fatty Acids, Volatile; D000644:Quaternary Ammonium Compounds; D013431:Sulfates; C012036:sodium sulfate; D013455:Sulfur; D008715:Methionine; D009584:Nitrogen