Effects of sulfur and monensin concentrations on in vitro dry matter disappearance, hydrogen sulfide production, and volatile fatty acid concentrations in batch culture ruminal fermentations

D. R. Smith, N. DiLorenzo, J. Leibovich, M. L. May, M. J. Quinn, J. W. Homm, M. L. Galyean

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31 Scopus citations

Abstract

Effects of monensin (MON) and S on in vitro fermentation and H2S production were evaluated in 2 experiments. In Exp. 1, 2 ruminally cannulated steers were adapted (>14 d) to a 75% concentrate diet [steam-flaked corn (SFC)-based], and ruminal fluid was collected approximately 4 h after feeding. Substrate composed (DM basis) of 85.2% SFC, 9% alfalfa hay, 5% cottonseed meal, and 0.8% urea was added with ruminal fluid and buffer to sealed 125-mL serum bottles to allow for gas collection. A Na2SO4 solution was added to yield S equivalent to 0.2, 0.4, and 0.8% of substrate DM, and MON was included at 0, 2, 4, and 6 mg/L of culture volume. Bottle head-space gas was analyzed for H2S. No MON (P = 0.29) or MON × S interaction (P = 0.41) effects were detected for H2S production. Increasing S linearly increased (P < 0.01) H2S production (μmoles/g of fermented DM). The IVDMD (average 70.0%) was not affected by MON (P = 0.93), S (P = 0.18), or the MON × S interaction (P = 0.56). Total VFA concentrations were not affected by MON (P = 0.87), S (P = 0.14), or the MON × S interaction (P = 0.86), but increasing MON linearly decreased (P ≤ 0.01) molar proportions of acetate, butyrate, and the acetate:propionate ratio (A:P), and linearly increased (P < 0.01) the proportion of propionate. In Exp. 2, 2 additional ruminally cannulated Jersey steers were adapted (>21 d) to a 75% concentrate diet (SFC base) that contained 15% (DM basis) wet corn distillers grains plus solubles (WDGS) and MON at 22 mg/kg of DM. In vitro substrate DM was composed of 75.4% SFC, 15% WDGS, 9% alfalfa hay, and 0.6% urea, and S and MON concentrations were the same as in Exp. 1. No effects of MON (P = 0.93) or the MON × S interaction (P = 0.99) were noted for H2S production; however, increasing S linearly increased (P < 0.01) H2S production. No effects of MON (P = 0.16), S (P = 0.43), or the MON × S interaction (P = 0.10) were noted for IVDMD (average 70.9%). Total VFA concentrations were not affected by MON (P = 0.40), S (P = 0.26), or the MON × S interaction (P = 0.59). As in Exp. 1, increasing MON linearly decreased (P < 0.05) molar proportions of acetate, butyrate, and A:P and linearly increased (P < 0.01) propionate. Increasing S concentration increased in vitro H2S production, but S did not affect VFA concentrations and proportions. Monensin did not affect in vitro H2S production, and changes in VFA molar proportions were evident with MON regardless of S concentration.

Original languageEnglish
Pages (from-to)1503-1512
Number of pages10
JournalJournal of animal science
Volume88
Issue number4
DOIs
StatePublished - Apr 2010

Keywords

  • Hydrogen sulfide
  • In vitro fermentation
  • Monensin
  • Sulfur

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