A recent investigation found that condensed tannins could exhibit a reduction in methane production in an in vitro gas production test [21]. Further investigation into the diversity of 16S rRNA gene library of rumen methanogen in the condensed tannin

treatment library revealed 21.9% higher diversity of sequences related to the TALC methanogens and a lower diversity of those associated with orders Methanobacteriales (15.1%) and Methanomicrobiales (6.8%) [22]. This shows a possible association between reduction in methane production and diversity of rumen methanogen. In the current study, yak has present higher methanogen diversity and significant different methanogen PERK modulator inhibitor community structures compared with cattle (Figure 1). While there are many factors which may explain these differences in methanogen diversity, it is possible that these differences between the methanogen GSK1904529A in vitro diversity in yak and cattle could be related to the significant difference in enteric methane production by both these ruminant species. Long [23] reported a significantly high level of propionic acid, which leads to efficient energy utilization and this further suggested a low methane production

in yak. Yak has also been found MCC950 cell line to exhibit lower methane output [9]. In the present study, yak had higher levels of acetate, proprionate, isobutyric, isovaleric and total volatile fatty acids than cattle, but cattle had higher acetate to proprionate (A/P) ratios (Table 2). This may also suggest different methanogenesis pathways. Therefore, the diversity and community structure of methanogens

in yak, which is the lower methane producing ruminant species in current study, correlates with data reported by Tan et al [22]. Table 2 The concentrations of volatile fatty acids from yak and cattle mafosfamide rumen samples Volatile fatty acids Yak (mmol/L) Cattle (mmol/L) Standard error Significance Acetate 58.56 42.57 3.18 p < 0.004 Propionate 12.13 7.35 0.93 p < 0.001 Isobutyric 0.88 0.60 0.06 p < 0.016 Butyrate 9.03 7.25 0.49 p < 0.09 Isovaleric 1.02 0.51 0.12 p < 0.027 Valeric 0.07 0.13 0.06 p < 0.728 Total volatile fatty acids 81.69 58.41 4.61 p < 0.001 A/P (Acetate to Propionate) 4.83 5.80 0.19 p < 0.004 * Concentrations of volatile fatty acids was analysed by gas chromatograph equipped with a DB-FFAP column (30 m × 0.25 μm × 0.25 μm; Agilent Technologies). Wright et al [24] revealed 65 sequences of methanogens by phylogenetic analysis from the Australian sheep rumen, and 62 of them belonged to the genus Methanobrevibacter. They were grouped with Methanobrevibacter NT7, Methanobrevibacter SM9, Methanobrevibacter M6, Methanobrevibacter ruminantium, Methanobrevibacter acididurans and Methanobrevibacter thaueri.