title: Effect of dietary fiber on the methanogen community in the hindgut of Lantang gilts.
abstract: The primary objective of this study was to investigate the effect of dietary fiber on methanogenic diversity and community composition in the hindgut of indigenous Chinese Lantang gilts to explain the unexpected findings reported earlier that Lantang gilts fed low-fiber diet (LFD) produced more methane than those fed high-fiber diet (HFD). In total, 12 Lantang gilts (58.7±0.37 kg) were randomly divided into two dietary groups (six replicates (pigs) per group) and fed either LFD (NDF=201.46 g/kg) or HFD (NDF=329.70 g/kg). Wheat bran was the main source of fiber for the LFD, whereas ground rice hull (mixture of rice hull and rice bran) was used for the HFD. Results showed that the methanogens in the hindgut of Lantang gilts belonged to four known species (Methanobrevibacter ruminantium, Methanobrevibacter wolinii, Methanosphaera stadtmanae and Methanobrevibacter smithii), with about 89% of the methanogens belonging to the genus Methanobrevibacter. The 16S ribosomal RNA (rRNA) gene copies of Methanobrevibacter were more than three times higher (P0.05) was observed in 16S rRNA gene copies of Fibrobacter succinogenes between the two dietary groups, and 18S rRNA gene copies of anaerobic fungi in gilts fed LFD were lower than (P<0.05) those fed HFD. To better explain the effect of different fiber source on the methanogen community, a follow-up in vitro fermentation using a factorial design comprised of two inocula (prepared from hindgut content of gilts fed two diets differing in their dietary fiber)×four substrates (LFD, HFD, wheat bran, ground rice hull) was conducted. Results of the in vitro fermentation confirmed that the predominant methanogens belonged to the genus of Methanobrevibacter, and about 23% methanogens was found to be distantly related (90%) to Thermogymnomonas acidicola. In vitro fermentation also seems to suggest that fiber source did change the methanogens community. Although the density of Methanobrevibacter species was positively correlated with CH4 production in both in vivo (P<0.01, r=0.737) and in vitro trials (P<0.05, r=0.854), which could partly explain the higher methane production from gilts fed LFD compared with those in the HFD group. Further investigation is needed to explain how the rice hull affected the methanogens and inhibited CH4 emission from gilts fed HFD.
authors.affiliation: 1College of Animal Science,South China Agricultural University,Guangzhou 510642,China.
authors.forename: Z
authors.initials: Z
authors.lastname: Cao
authors.affiliation: 2Institute of Tropical Agriculture,Universiti Putra Malaysia,43400 Serdang,Malaysia.
authors.forename: J B
authors.initials: JB
authors.lastname: Liang
authors.affiliation: 1College of Animal Science,South China Agricultural University,Guangzhou 510642,China.
authors.forename: X D
authors.initials: XD
authors.lastname: Liao
authors.affiliation: 3School of Animal and Comparative Biomedical Sciences,College of Agriculture and Life Sciences,University of Arizona,Tucson, AZ 85721,USA.
authors.forename: A D G
authors.initials: AD
authors.lastname: Wright
authors.affiliation: 1College of Animal Science,South China Agricultural University,Guangzhou 510642,China.
authors.forename: Y B
authors.initials: YB
authors.lastname: Wu
authors.affiliation: 4Agro-Animal Husbandry Co., Ltd.,Shenzhen,Guangdong 518023,China.
authors.forename: B
authors.initials: B
authors.lastname: Yu
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004032:Diet / Q000662:veterinary; D004043:Dietary Fiber / Q000494:pharmacology*; D005260:Female; D005285:Fermentation; D041981:Gastrointestinal Tract / Q000382:microbiology; D008697:Methane / Q000378:metabolism*; D041581:Methanobrevibacter / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013552:Swine / Q000382:microbiology* / Q000523:psychology
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004043:Dietary Fiber; D008697:Methane
keywords: Lantang gilts; Methanobrevibacter; dietary fiber; methanogen community