Polysaccharide utilization by gut bacteria: potential for new insights from genomic analysis

Flint, Harry J.; Bayer, Edward A.; Rincón, Marco T.; Lamed, Raphael; White, Bryan A.

doi:10.1038/nrmicro1817

Cited by 1,444 publications

(1,079 citation statements)

References 124 publications

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“…However, in practice, it is difficult to evaluate this scientifically, as no two feed ingredients are identical in all constituents bar starch and fibre. In the present study, there were also numerical differences in OM, ADF, ether extract and WSC between the two concentrate sources, all of which could alter rumen fermentation pathways within the rumen (Latham et al, 1971) and alter the ruminal microbial diversity (Flint et al, 2008).…”

Section: Feed Compositionmentioning

confidence: 54%

The influence of grass silage-to-maize silage ratio and concentrate composition on methane emissions, performance and milk composition of dairy cows

Hart

Huntington

Wilkinson

et al. 2015

Animal

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It is well-established that altering the proportion of starch and fibre in ruminant diets can alter ruminal and post-ruminal digestion, although quantitative evidence that this reduces enteric methane (CH 4 ) production in dairy cattle is lacking. The objective of this study was to examine the effect of varying grass-to-maize silage ratio (70 : 30 and 30 : 70 DM basis), offered ad libitum, with either a concentrate that was high in starch or fibre, on CH 4 production, intake, performance and milk composition of dairy cows. A total of 20 cows were allocated to one of the four experimental diets in a two-by-two factorial design run as a Latin square with each period lasting 28 days. Measurements were conducted during the final 7 days of each period. Cows offered the high maize silage ration had a higher dry matter intake (DMI), milk yield, milk energy output and lower CH 4 emissions when expressed per kg DMI and per unit of ingested gross energy, but there was no difference in total CH 4 production. Several of the milk long-chain fatty acids (FA) were affected by forage treatment with the most notable being an increase in 18:0, 18:1 c9, 18:2 c9 c12 and total mono unsaturated FA, observed in cows offered the higher inclusion of maize silage, and an increase in 18:3 c9 c12 c15 when offered the higher grass silage ration. Varying the composition of the concentrate had no effect on DMI or milk production; however, when the high-starch concentrate was fed, milk protein concentration and milk FAs, 10:0, 14:1, 15:0, 16:1, increased and 18:0 decreased. Interactions were observed for milk fat concentration, being lower in cows offered high-grass silage and high-fibre concentrates compared with the high-starch concentrate, and FA 17:0, which was the highest in milk from cows fed the high-grass silage diet supplemented with the high-starch concentrate. In conclusion, increasing the proportion of maize silage in the diets of dairy cows increased intake and performance, and reduced CH 4 production, but only when expressed on a DM or energy intake basis, whereas starch-to-fibre ratio in the concentrate had little effect on performance or CH 4 production.Keywords: methane, dairy cows, forage, SF 6 tracer ImplicationsMethane production by ruminants is becoming an increasing concern due to its contribution to greenhouse gas emissions. Dietary strategies to reduce methane production in terms of supplying dietary supplements can result in pollution swapping, and are therefore not desirable. Researchers examine the effect of changing the ratio of grass and maize silage in addition to changing the amount of starch and fibre in the concentrate. The results obtained are related to national greenhouse gas inventories and potential effects of cropping systems on greenhouse gas emissions along with animal performance. IntroductionGlobally, agriculture, forestry and land use change account for 56% of non CO 2 anthropogenic greenhouse gas emissions, with methane (CH 4 ) from enteric fermentation accounting for 36% of this (Smith et al., 2014...

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Section: Feed Compositionmentioning

confidence: 54%

The influence of grass silage-to-maize silage ratio and concentrate composition on methane emissions, performance and milk composition of dairy cows

Hart

Huntington

Wilkinson

et al. 2015

Animal

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“…SCFA have been implicated to have both local and systemic beneficial biological effects in the human body; acetate is readily absorbed and transported to the liver; propionate is a substrate for hepatic gluconeogenesis; butyrate is the preferred fuel of the colonocytes and also plays a major role in the regulation of cell proliferation and differentiation (7) . Several excellent review-papers already exist (130,(142)(143)(144)(145)(146)(147) , and therefore we will not go into detail with the dietary interventions with fibre.…”

Section: Fermentable Dietary Carbohydratesmentioning

confidence: 99%

“…), resistant starch (stimulates bifidobacteria, Bacteroides spp., Ruminococcus bromii, E. rectale and Roseburia spp. ), β-glucan (stimulates bifidobacteria) and fructan (stimulates bifidobacteria, Bacteroides spp., lactobacilli and butyrate-producers) are well recognised (144,(154)(155)(156)(157)(158)(159)(160)(161) . In addition, arabinoxylan-oligosaccharides, which are enzymatic hydrolysis products of arabinoxylan, have been shown to stimulate the growth of bifidobacteria in some studies (156) .…”

Section: Fermentable Dietary Carbohydratesmentioning

confidence: 99%

Human gut microbiota: does diet matter?

2014

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The human oro-gastrointestinal (GI) tract is a complex system, consisting of oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus, which all together with the accessory digestive organs constitute the digestive system. The function of the digestive system is to break down dietary constituents into small molecules and then absorb these for subsequent distribution throughout the body. Besides digestion and carbohydrate metabolism, the indigenous microbiota has an important influence on host physiological, nutritional and immunological processes, and commensal bacteria are able to modulate the expression of host genes that regulate diverse and fundamental physiological functions. The main external factors that can affect the composition of the microbial community in generally healthy adults include major dietary changes and antibiotic therapy. Changes in some selected bacterial groups have been observed due to controlled changes to the normal diet e.g. high-protein diet, high-fat diet, prebiotics, probiotics and polyphenols. More specifically, changes in the type and quantity of non-digestible carbohydrates in the human diet influence both the metabolic products formed in the lower regions of the GI tract and the bacterial populations detected in faeces. The interactions between dietary factors, gut microbiota and host metabolism are increasingly demonstrated to be important for maintaining homeostasis and health. Therefore the aim of this review is to summarise the effect of diet, and especially dietary interventions, on the human gut microbiota. Furthermore, the most important confounding factors (methodologies used and intrinsic human factors) in relation to gut microbiota analyses are elucidated.

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“…The reasons why host diet has a strong impact on the gut microbial composition are still not well understood (De Filippo et al, 2010;Muegge et al, 2011;Turnbaugh et al, 2009), but presumably reflects a combination of influences on the physical and chemical milieu of the gut (Clissold et al, 2010;Duncan et al, 2008;Faith et al, 2011;Flint et al, 2008;Ley et al, 2008;Sorensen et al, 2010), and effects on immune responses (see above). Also, the diet itself is a vector of commensals, and different diets will provide microbial inoculates of different community compositions.…”

Section: Microbiota: a Key Component Of Nutritional Immunologymentioning

confidence: 99%