# Effects of 2-bromoethanesulfonate alone or in combination with calcium propionate or monensin on methane and gaseous hydrogen production during in vitro rumen fermentation

## TL;DR

This study tested how adding 2-bromoethanesulfonate with monensin or calcium propionate affects methane and hydrogen gas production in a lab model of rumen fermentation.

## Contribution

The study introduces a potential short-term strategy to reduce hydrogen gas production when using methane mitigators in ruminants.

## Key findings

- Treatments with 2-bromoethanesulfonate reduced methane production compared to the control.
- Monensin and calcium propionate further reduced hydrogen gas production when combined with 2-bromoethanesulfonate.
- Hydrogen production was higher in 2-bromoethanesulfonate treatments than in the control at 8 hours.

## Abstract

Summary: This experiment evaluated the effect of 2-bromoethanesulfonate in combination with monensin or calcium propionate on in vitro gaseous CH4 and H2 production. Gas pressure and composition data were collected at 0, 4, 8, 18, 24, and 48 hours of fermentation. Results suggest all treatments containing 2-bromoethanesulfonate reduced CH4 production, but monensin may further reduce CH4 compared with 18 hours of 2-bromoethanesulfonate alone. The addition of monensin and calcium also reduced H2, and this observation serves as evidence that the compounds may serve as a short-term strategy to reduce gaseous H2 production when CH4 mitigators such as 2-bromoethanesulfonate are used to reduce enteric CH4 production.

Summary: This experiment evaluated the effect of 2-bromoethanesulfonate in combination with monensin or calcium propionate on in vitro gaseous CH4 and H2 production. Gas pressure and composition data were collected at 0, 4, 8, 18, 24, and 48 hours of fermentation. Results suggest all treatments containing 2-bromoethanesulfonate reduced CH4 production, but monensin may further reduce CH4 compared with 18 hours of 2-bromoethanesulfonate alone. The addition of monensin and calcium also reduced H2, and this observation serves as evidence that the compounds may serve as a short-term strategy to reduce gaseous H2 production when CH4 mitigators such as 2-bromoethanesulfonate are used to reduce enteric CH4 production.

•2-Bromoethanesulfonate (BE) decreased methane gas production in vitro.•Monensin may increase CH4 mitigation effects when paired with BE.•Monensin and calcium propionate may serve to reduce gaseous H2 production.

2-Bromoethanesulfonate (BE) decreased methane gas production in vitro.

Monensin may increase CH4 mitigation effects when paired with BE.

Monensin and calcium propionate may serve to reduce gaseous H2 production.

Some feed additives that mitigate enteric methane (CH4) production can result in an increase in hydrogen (H2) production. When expelled to the environment, H2 may intensify competition for hydroxyl radicals, prolonging CH4 persistence in the atmosphere. Therefore, the objective of the experiment was to determine the effects of adding 2-bromoethanesulfonate (BE) alone and in combination with monensin or calcium propionate on in vitro ruminal CH4 and H2 production. Using 3 separate runs, 1 g of 50% corn silage and 50% alfalfa (DM basis) was fermented (1) alone (control; CON); (2) CON with 100 μM BE (BES); (3) BES + 2.5 μM monensin (BM); and (4) BES + 2.5% DM calcium propionate (BC). Inoculum was obtained by collecting a mixture of rumen fluid from 2 steers (BW = 657 ± 12.5 kg) consuming a diet of 30% concentrate and 70% roughage. For each treatment within run, gas production was measured over a 48-h period using 2 randomly assigned paired and separate modules. Total CH4 and H2 production were calculated by multiplying the total volume of gas produced by the concentration of CH4 and H2 determined by gas chromatography at 0, 4, 8, 18, 24, and 48 h. Data were blocked by run and analyzed as a repeated measures randomized complete block design using the GLIMMIX procedure of SAS (v. 9.4) where treatment, time and the interaction between these 2 factors were considered as fixed effects and module, run and the interaction were included as random effects. Significance was declared at P ≤ 0.05. The BES, BM, and BC treatments did not differ in CH4 production (g/h) at 4 and 8 h of incubation, averaging 0.005 and 0.013 ± 0.0020 g/h, respectively, but CH4 production was reduced compared with the CON (0.017 and 0.047 ± 0.0018 g/h CH4, respectively). At 8 h, BES increased H2 production relative to BM and BC (0.002 and 0.0014 ± 0.0002 g/h H2, respectively), but all treatments containing BES were significantly greater than CON (0 vs. 0.002 ± 0.0002 H2 g/h). In conclusion, treatments containing BES reduced CH4, and the addition of calcium propionate or monensin may serve as a short-term strategy for the reduction of H2 resulting from mitigation of enteric CH4 production.