Effects of Monensin, Pyromellitic Diimide and 2-Bromoethanesulfonic Acid on Rumen Fermentation In Vitro2

Abstract

The effects of monensin, 2-bromoethanesulfonic acid (2-BES) and pyromellitic diimide (diimide) on gas and volatile fatty acid (VFA) production by the rumen microbiota were compared in mixed culture. Oat hay, a hay-concentrate mixture (48% hay, 43% concentrate) and a soluble carbohydrate mixture were used as substrates for microbial growth. The highest concentrations of diimide (10 ppm) and 2-BES (30 microM) decreased methanogenesis by 97 and 76%, respectively, while H2 accumulation was increased 30- and 20-fold, respectively. The effect of monensin on methanogenesis was less dramatic as 10 ppm decreased CH4 accumulation 16% and H2 did not accumulate. Diimide and 2-BES decreased the acetate:propionate ratio with the hay (P less than .05) and soluble carbohydrate mixture (P less than .025). The numbers of saccharolytic, cellulolytic and methanogenic bacteria from sheep fed a diet with diimide (60 ppm) did not differ significantly from sheep fed a control diet. Semicontinuous culture incubations indicated that the mixed rumen microbial population could adapt and degrade diimide after 24 h of incubation.

Effects of exogenous fibrolytic enzymes, α-bromoethanesulfonate and monensin on fermentation in a rumen simulation (RUSITEC) system

“…α-Bromoethanesulfonate (72 µM) depressed (P < 0.01) methane production per unit of digestible OM by 51% (Table 1). This observation is consistent with an earlier in vitro study (Martin and Macy 1985) and with short-term results with sheep (Immig et al 1996). α-Bromoethanesulfonate did not influence either total or cellulolytic bacterial populations, but it significantly inhibited (P < 0.05) growth of methanogenic bacteria (Table 2).…”

“…Uptake of HS-CoM by whole cells of M. ruminantium was completely inhibited by 1 µM BES (Balch and Wolfe 1979). Martin and Macy (1985) observed that 30 µM BES reduced methane production by 76% in mixed cultures of ruminal fluid. Similarly, effects have been observed in vivo; intraruminal administration of BES to sheep also depressed methane production, although the effect disappeared after 3 d (Immig et al 1996).…”

Reducing in vitro rumen methanogenesis for two contrasting diets using a series of inclusion rates of different additives

“…It is not known why PMDI affected the aDMd of ryegrass and not GS+B. The reduction in aDMd of ryegrass with the addition of PMDI was somewhat surprising and not observed in previous in vivo studies (Martin and Macy 1985;Eijssen et al 1990). Goel et al (2009) reported the reduction of in vitro methane output using 5 mM BCM with hay as substrate, compared with between 1 and 5 mM BCM required for ryegrass and GS+B in the present study.…”

“…Although not a HMA, in other reports (Van Nevel and Demeyer 1995;Choi et al 2004) PMDI has been grouped with HMA, primarily because it is thought to share a similar action as BES to inhibit methanogenesis (Martin and Macy 1985). PMDI adversely affected the in vitro fermentation of both feeds to a greater extent than did BES or BCM, as evidenced by the lower aDMd for ryegrass and a lower tVFA/ DMi for both feeds with PMDI.…”

“…PMDI is a potent inhibitor of rumen methanogenesis (Martin and Macy 1985). Although not a HMA, in other reports (Van Nevel and Demeyer 1995;Choi et al 2004) PMDI has been grouped with HMA, primarily because it is thought to share a similar action as BES to inhibit methanogenesis (Martin and Macy 1985).…”