26 research outputs found
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Flaxseed supplementation decreases methanogenic gene abundance in the rumen of dairy cows
The objective of this study was to investigate the effects of a flaxseed-supplemented diet on archaeal abundance and gene
expression of methanogens in the rumen of dairy cows. In all, 11 non-lactating dairy cows were randomly divided into two
groups: group A (five cows) and B (six cows). The two diets fed were: (1) the control diet, a conventional dry cow ration; and
(2) the flaxseed-supplemented diet, the conventional dry cow ration adjusted with 12.16% ground flaxseed incorporated into the
total mixed ration. A cross-over experiment was performed with the two groups of cows fed the two different diets for five 21-day
periods, which included the first adaptation period followed by two treatment and two wash out periods. At the end of each
feeding period, rumen fluid samples were collected via rumenocentesis and DNA was extracted. Quantitative PCR was utilized
to analyze the gene abundance of 16S ribosomal RNA (16S rRNA) targeting the ruminal archaea population and the mcrA gene
coding for methyl coenzyme-M reductase subunit A, a terminal enzyme in the methanogenesis pathway. Results demonstrated
a 49% reduction of 16S rRNA and 50% reduction of mcrA gene abundances in the rumen of dairy cows fed the flaxseedsupplemented
diet in comparison with those fed the control diet. This shows flaxseed supplementation effectively decreases
the methanogenic population in the rumen. Future studies will focus on the mechanisms for such reduction in the rumen
of dairy cattle, as well as the relationship between methanogenic gene expression and methane production.Keywords: Dairy cattle, Mcra, Methanogenic gene, Flaxsee
Composition, Diversity, and Origin of the Bacterial Community in Grass Carp Intestine
Gut microbiota has become an integral component of the host, and received increasing attention. However, for many domestic animals, information on the microbiota is insufficient and more effort should be exerted to manage the gastrointestinal bacterial community. Understanding the factors that influence the composition of microbial community in the host alimentary canal is essential to manage or improve the microbial community composition. In the present study, 16S rRNA gene sequence-based comparisons of the bacterial communities in the grass carp (Ctenopharyngodon idellus) intestinal contents and fish culture-associated environments are performed. The results show that the fish intestinal microbiota harbors many cellulose-decomposing bacteria, including sequences related to Anoxybacillus, Leuconostoc, Clostridium, Actinomyces, and Citrobacter. The most abundant bacterial operational taxonomic units (OTUs) in the grass carp intestinal content are those related to feed digestion. In addition, the potential pathogens and probiotics are important members of the intestinal microbiota. Further analyses show that grass carp intestine holds a core microbiota composed of Proteobacteria, Firmicutes, and Actinobacteria. The comparison analyses reveal that the bacterial community in the intestinal contents is most similar to those from the culture water and sediment. However, feed also plays significant influence on the composition of gut microbiota