Methanogens and Methanogenesis in the Rumens and Ceca of Lambs Fed Two Different High-Grain-Content Diets

Abstract

The amount and nature of dietary starch are known to influence the extent and site of feed digestion in ruminants. However, how starch degradability may affect methanogenesis and methanogens along the ruminant's digestive tract is poorly understood. This study examined the diversity and metabolic activity of methanogens in the rumen and cecum of lambs receiving wheat or corn high-graincontent diets. Methane production in vivo and ex situ was also monitored. In vivo daily methane emissions (CH 4 g/day) were 36% (P < 0.05) lower in corn-fed lambs than in wheat-fed lambs. Ex situ methane production (mol/h) was 4-fold higher for ruminal contents than for cecal contents (P < 0.01), while methanogens were 10-fold higher in the rumen than in the cecum (mcrA copy numbers; P < 0.01). Clone library analysis indicated that Methanobrevibacter was the dominant genus in both sites. Diet induced changes at the species level, as the Methanobrevibacter millerae-M. gottschalkii-M. smithii clade represented 78% of the sequences from the rumen of wheat-fed lambs and just about 52% of the sequences from the rumen of the corn-fed lambs. Diet did not affect mcrA expression in the rumen. In the cecum, however, expression was 4-fold and 2-fold lower than in the rumen for wheat-and corn-fed lambs, respectively. Though we had no direct evidence for compensation of reduced rumen methane production with higher cecum methanogenesis, the ecology of methanogens in the cecum should be better considered.

Examination of the Rumen Bacteria and Methanogenic Archaea of Wild Impalas (Aepyceros melampus melampus) from Pongola, South Africa

“…In the present study, Methanobrevibacter species were the most dominant methanogens from the four impalas, similar to previous studies on a range of host species including Mediterranean water buffalo on three different diets in Brazil, sheep from Venezuela, sheep from Western Australia on three different diets, lambs on different high-grain diets in France, lactating Jersey and Holstein cows in Vermont, alpaca from Vermont, and in the Hoatzin from South America [24,26,[41][42][43][44][45]. However, at the species level, the majority of the 16S rRNA gene sequence reads from the highest represented OTU had the highest sequence identity to M. thaueri, a methanogen first isolated from cow feces and a member of the Methanobrevibacter smithii-gottschalkii-millerae-thaueri (SGMT) clade that uses hydrogen and carbon dioxide to produce methane [24,46].…”

Characterization of the Microbial Communities in Rumen Fluid Inoculated Reactors for the Biogas Digestion of Wheat Straw

“…In bovine rumen, methanogens predominantly utilize H 2 -CO 2 as substrates to produce methane [13], which was supported by the prevalence of hydrogenotrophic Methanobrevibacter in this study and previous studies [11,12,40,41]. In addition to the predominance of hydrogenotrophic methanogenesis, methylotrophic methanogenesis in bovine rumen might be undertaken by Methanomassiliicoccus, the growth of which could be enhanced by methylamine supplement [42].…”

“…The non-fibrolytic bacteria, such as Succinivibrio dextrinosolvens, Selenomonas ruminantium, and Anaerovibrio lipolytica could facilitate plant fiber digestion in the rumen [10]. Additionally, rumen methane production, which is mainly due to the hydrogenotrophic Methanobrevibacter, is also a subject of concern for its contribution to the greenhouse gas increment [11,12]. In rumen, the aceticlastic pathway was not important with low numbers of Methanosarcina retrieved [13,14].…”

Relationship between in vitro and in vivo methane production measured simultaneously with different dietary starch sources and starch levels in dairy cattle

“…However, there is substantial variation in the in vitro fermentation kinetics of different starch sources (Cone and Becker, 2012). Inclusion of these starch sources in the diets of animals also influences rumen fermentation differently, and hence leads to variability in the reduction of CH 4 produced (Beauchemin and McGinn, 2005;Popova et al, 2013). Above all, in vitro and in vivo studies are usually performed separately under different conditions and there is a lack of direct in vitro-in vivo comparison, which is essential to demonstrate the robustness or effectiveness of the in vitro GP technique in simulating rumen fermentation.…”