title: Supplemental vitamin C improves marbling in feedlot cattle consuming high sulfur diets.
abstract: The objective of this study was to examine the effects of supplemental rumen-protected vitamin C (VC) on live and carcass-based performance, and antioxidant capacity of cattle consuming varying concentrations of dietary S. Angus-cross steers (n = 120) were blocked by initial BW (341 ± 11 kg) and assigned equally to 1 of 6 treatments, evaluating 3 concentrations of dietary S [0.22%, 0.34%, and 0.55%, for low S (LS), medium S (MS), and high S (HS), respectively] and 2 concentrations of supplemental VC (0 or 10 g • steer(-1) • d(-1)). Steers receiving VC-supplemented diets consumed an average of 10.3 g of supplemental VC • steer(-1) • d(-1) and increasing dietary S linearly increased (P < 0.01) grams of S consumed. Increasing dietary S decreased (P < 0.01) DMI, final BW, and ADG, and linearly increased (P < 0.05) rumen hydrogen sulfide and blood sulfhemoglobin concentrations. The inclusion of VC, regardless of S treatment, tended to increase (P = 0.08) plasma VC concentrations, specifically within the medium and high S diets (P = 0.04). Plasma total antioxidant capacity (d 90) linearly decreased (P = 0.003) and total liver glutathione (GSH; d 143) tended to decrease (P = 0.08) due to increased S intake. Within the high S treatment, addition of VC decreased (P = 0.04) the ratio of oxidized-to-reduced GSH compared with HS alone. Increased dietary S and VC decreased (P < 0.05) plasma Cu concentrations, whereas VC increased (P = 0.01) plasma Fe concentrations. Linear decreases (P < 0.02) in marbling score, backfat thickness (BF), yield grade, and HCW were observed as dietary S increased; however, the addition of VC to the HS diet increased (P < 0.01) BF, marbling scores, and percentage of cattle grading Choice compared with HS without VC. In conclusion, supplementation of VC to cattle receiving the high S diet improved marbling scores; although the exact mechanism for this improvement is unknown, it may be related to greater circulating VC available for lipid metabolism in these cattle.
authors.affiliation: Department of Animal Science and Interdepartmental Graduate Program in Nutritional Sciences, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Pogge
authors.forename: S L
authors.initials: SL
authors.lastname: Hansen
mesh_terms: D050154:Adiposity / Q000187:drug effects*; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood*; D001823:Body Composition; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D008297:Male; D008460:Meat / Q000032:analysis*; D011897:Random Allocation; D012417:Rumen / Q000502:physiology; D013054:Spectrophotometry, Atomic / Q000662:veterinary; D013457:Sulfur Compounds / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D013457:Sulfur Compounds; D001205:Ascorbic Acid