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

Abstract

Abstract. Eleven individual additives were incubated with either perennial ryegrass or with grass silage+barley grain (50 : 50) and the in vitro methane output was assessed using the gas production technique (GPT). Additives were: fatty acids (lauric, oleic, linoleic and linolenic acids), halogenated methane analogues (bromoethanesulfonate and bromochloromethane), pyromellitic diimide, statins (mevastatin and lovastatin), a probiotic (Saccharomyces cerevisiae) and an unsaturated dicarboxylic acid (fumaric acid). Each additive was included at a range of concentrations. Effects on methane output per gram of feed dry matter (DM) incubated (CH 4 /DMi) and disappeared (CH 4 /DMd), as well as other fermentation variables, were evaluated after 24 h of incubation. The addition of increased concentrations of individual fatty acids, bromoethanesulfonate and pyromellitic diimide caused a dose-dependent decline in methane output (CH 4 /DMi, CH 4 / DMd), when incubated with either perennial ryegrass or grass silage+barley grain. No methane output was detected for either feed with the addition of !5 mM bromochloromethane. The statins were ineffective inhibitors of methane output regardless of feed type. For perennial ryegrass, S. cerevisiae caused a dose-dependent decline in CH 4 /DMd and fumaric acid a dose-dependent decline in CH 4 /DMi and CH 4 /DMd. The effectiveness of lauric, oleic, linoleic and linolenic acids and bromoethanesulfonate to reduce methane output was more pronounced when incubated with grass silage+barley grain than with perennial ryegrass, and therefore the type of feed is an important component for any future in vitro and in vivo studies to be undertaken with these additives. Thus, incorporating different feed types in the initial in vitro screening protocols of all new additives is recommended.Additional keywords: in vitro total gas production technique, rumen fermentation modifiers, ruminant diets.

Effect of nanoemulsified oils addition on rumen fermentation and fatty acid proportion in a rumen simulation technique

“…The fish oil inclusion of different fatty acid composition as cited by Shingfield et al (2010) could lead to a decrease in the molar concentration of the acetate toward the increased concentration of propionate. Propionate-producing gram-negative bacteria are not significantly inhibited by the fatty acids (O'Brien et al, 2014), which could explain the lack of effect of the nanoemulsions containing fish oil on the molar proportions of propionate in the current study. The possible decrease in molar concentration of acetate caused by fish oil fatty acid could explain the decrease observed in total volatile fatty acid count by NEF and NEB supplementation.…”

Effects of 3-nitrooxypropanol on methane production using the rumen simulation technique (Rusitec)

“…However, the decrease in CH 4 production is not completely explained in stoichiometric terms by moderate increases in propionate concentration. Indeed, the use of specific CH 4 inhibitors has been related to hydrogen gas (H 2 ) accumulation both in vitro (Immig et al, 1996;Soliva et al, 2011;O'Brien et al, 2014) and in vivo using direct measurement (Immig et al, 1996;Mitsumori et al, 2012), or stoichiometric calculation (Mitsumori et al, 2012;Romero-Perez et al, 2015). Thus, we hypothesized that accumulation of excess H 2 would also occur with NOP use.…”

Design, implementation and interpretation of in vitro batch culture experiments to assess enteric methane mitigation in ruminants—a review

“…However, CH 4 production from soybean hulls with BES or cinnamaldehyde was 65% lower compared with soyhulls without additive after 72 h, suggesting an influence on adaptation, whereas no CH 4 was produced after 72 h production when maize was incubated with these additives. Subsequent studies covering a range of plant extracts and fatty acids (Castro-Montoya et al, 2012;Klevenhusen et al, 2012;O'Brien et al, 2013) have provided further evidence that responses of CH 4 to a given additive differs depending on the feed substrate incubated. For example, addition of fatty acids were found more effective in lowering CH 4 during incubations containing higher proportions of concentrate ingredients, an effect attributed to greater protonation of fatty acids at a lower pH (e.g.…”