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Revisiting how life depends on microbiota

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Advancia 2017 - Session 3

From scientific reviews to a roundtable addressing questions from the participants and a forum for more questions and answers.


The metabolic microbiota, Nutrition Ecology

  • Dr Filip VAN IMMERSEEL (Ghent University, Belgium)

Improving the digestive immune system, inflammation and gut health

  • Prof Theo NIEWOLD (Katholieke Univ. Leuven Universiteit, Belgium)

Indicators and biomarkers to appreciate gut health

  • Dr Elisabeth SANTIN (Univ. Fed do Parana, Curitiba, Brazil), Medicina veterinaria

Feeding the birds or the bugs, toward Nutrition Ecology

  • Prof Richard DUCATELLE; Prof Theo NIEWOLD
Your question / Our answers

Q: When regard to nutrient supply and metabolism, what proportion is utilized by microorganisms versus the proportion used by the animal itself ? And does the proportion change with the age of the bird or microbiota changes ?

In horses, it has been mesured that 80% of the maintenance can be explained by microbiota metabolism. Logically, the age is important as the microbot composition changes with increasing diversity and thus metabolic functions with age. So the microbial energy supplyshould be higher in older animals, but also microbial use of feed compounds would be enhanced. However, it might be not so clear to what extent the use of susbtrates and the production of metabolites that can be used by the host is distributed.

Q:  Regarding carbohydrates metabolism: what is the consistency of microorganism metabolism and beneficial  response given the variation in ingredient quality we face in the commercial side?

A good point to consider in feed formulation indeed but how? Most feed compositions for broilers are fairly similar, except when using low-quality ingredients or by-products  or even batches but with different qualities. We have not enough knowledge for these substrates, but installing a pre-screen batch fermentation and montoring metabolite production could help, although maybe practically not realistic.

Q:  Some Bacillus species secrete digestive enzymes. Is it possible to reduce NSPase in feed if you supplement with these bacteria? 

Never forget that microorganism producing enzymes will produce those enzymes when developing in the digestive tract thus rather in the distal period. Thus NSP will still limit accessibility to nutrients.

Q:  What is the effect of ambient temperature (hot vs cold) on intestinal inflammation and gut barrier integrity. 

High temperature, heat stress definitely promotes gut inflammation and degrades gut barrier integrity. Thus helping the animals to reinforce their gut barrier will prevent degrading performance

Q:  Regarding metabolic chain, would you recommend to add « butyrate producer microoragnisms » or the adding of butyrate directly in the feed? 

There are various possibilities, but it might be more long-term efficient to supply the right alternatives to stimulate growth and metabolism of butyrate producing microbiota.

Q:  Is there a difference between dietary butyrate and butyrate produced by the intestine.

Supplying directly butyrate either as is or in different forms, or prebiotics to stimulate the butyrate producers, or probiotics that would either produce or stimulate the butyrate producers are the different potential means. What is the best supply is not clear, but butyrate has to be delivered close to the enterocytes to be efficient and defnitely in a protected form to pass the stomach.

Q:  What is the challenge when we use butyric acid directly to the feed? What is preferable : to induce butyric acid, use it directly or both?  

It seems that the more sustainable approach is steering towards butyrate production with feed composition and additives.

Q: Can we expect the same beneficial effect of butyric acid and linoleic acid if these components were add to the feed or produced by microbiota?


It all depends on the way how butyrate procduction is induced, and which additives are used; There is a lot of variability, so it should be tested one-by-one, but there are large differences in outcome, depending on the disease or issues that are targeted.

Q:  What are the characteristics of the anaerobic butyrate producers ? Can’t we simply use these as probiotics? 

It is not an easy task.

Q:  Is it possible to « accelerate » the maturation of the microbiota ? How? 

Supplemementing with probiotics or prebiotics as early as possible will be the best way to influence the microbiota development.

Q: What would be your advice in feed formulation to fuel the gut facing health challenge?

a good question to address as it is key for the feed formulator to better understand its important role in influencing the gut functioning

Q: In a commercial feed (mash or pellet), should we adding a certain amount of small particle size wheat bran ? How much is enough?

Fine particles is clearly not positive as shown in pigs. Moreover there is an optimum here. With bran it has been shown that this is quite beneficial for stimulation of beneficial microbes and even 0,1% can help. Likely also there is an optimum in concentration and as always, too high will be countereffective.

Q:  What about mucin secretion in the intestines? Is that may help? 

This is not a targe, as too much mucin can even be a side effect of of coccidiosis or inflammation.

Q:  Is mucin secretion good or bad? 

it is indeed a protective mechanism, but if too much mucin production occurs it can allow more clostridia growth

Q:  How can we genetically map the chicken’s gut microbiome if we cannot culture all the microbes or know what all microbes might be? 

The metagenome project will demonstrate the potential and the importance of knowing better the complete microbiota and its variation according to various factors.

Q: In the microbiota, do we or can we, know exactly who eats what? 

Feeding the bugs directly or influencing the cross feeding meaning dealing more with nutrition ecology is key for future of nutrition. By separating the bacteria from the host and testing in vitro, it is possible to better identify substrates used but that is an approach that is time-consuming and not realistic on a large scale. Also the future genomic analysis tools will likely be able to produce metabolic maps for each bug.  

Q:  Which is the role of yeast in affecting microbiota and especially on bacteria producing butyric acid?

not yet studied too much

Q:  For sulfur-containing compounds, SH2 can be produced. How toxic is this SH2 to intestinal cells and is there a thereshold for SH2 and toxicity? 

Indeed H2S is detrimental for the functioning of microbiota, and at high concentrations, H2S is even toxic for epithelial cells.

Q:  Do you think that intestinal inflammation in our fast growing broiler could explain some of the muscles problems we talked about yesterday (myopathies). 

It might contribute but rather indirectly as redox imbalance is suggested to be involved in myopathies

Q:   Would you be able to evaluate metabolic costs vs. Metabolic benefit in hind gut?

Indeed microbiota and gut maintenance requirement is significantly affecting the energy and nutrient metabolism but SCFA production is also supplying metabolites and significant amount of energy to adult animals.

Q:  If inducing immunity involves cost, is it necessary to supplement immunomodulators in feed? 

Immunomodulators will help the gut to better support challenges

Q:  Many different tests are used to show anti inflammatory effects ... How can we make sure that we are not too far away from what can be expected in vivo?

There is usually a good relationship except for compounds such as unencapsulated butyrate which cannot reach the small intestine.

Q:  Any thoughts or admitted links between inflammation and oxydation at intestinal level?

Indeed inflammation is involving redox mechanisms and oxidative balance.

Q:  How can you know, without having analyzed this, that the AGPs, cyclins, or even poppy plume is not affecting microbiota composition? 

A good point as recent developments show that microbiota will be affected even with pretty low level of antibiotics as used as AGP's.

Q: Is hypothesis that antibiotics are anti-inflammatory not because of effect on microbiota? 

maybe both mechanisms

Q:  Could yeast cell wall help to improve intestinal health? 

  Certain components of yeast cell walls would have an effect on gut health.

Q: When can the poultry industry expect an easy-to-measure fecal biomaker for gut health? 

A good point that biomarkers would be fundamental to further develop relevant solutions to improve gut functioning solutions. Ghent Univ hope than in 3 years a test kit could be available, a lot of molecules are potential targets now and need to be validated in field conditions.

Q:  Do we have non invasive biomakers yet? Are these being developed by scientists? 

 Practical biomarkers should not be too long to be available for the industry.

Q: Qualitative markers are good, but what about quantitative ones?

They are quantitative in pigs, no reason why they shouldn't quantitative too in broilers.

Q: Do you know a biomarker of bad balance of the bird’s microbiota? Do you think the detection of such a marker could help anticipate dysbiosis? 

Well, enterobacteraceae are described as markers for poor gut health, and the butyrate producers (eg by measuring the gene copies for the butyrate production enzyme) as positive markers

Q:  Are markers used in humans intestinal inflammation (e.g: ibd), not usefull? 

There is difference between humans and birds relevant markers, recent developments will shortly help to better understand the key factors to improve gut balance and health. However, there is not enough homology at protein level, so human kits do not work in chickens.

Q:  Can we simply test human calprotein tests with fecal sample of chickens? 

The problem here is twofold, 1. birds do have different systems (e;g; miss MPO), and if the have the same proteins, the mammal antibodies do not work.

Q:  At what age should we measure biomarkers for gut health? 

As early as possible to be able to understand how to influence but can be done  at any age with sufficient faeces. The target should be before the onset of problems, eg 2 weeks, so that we can predict problems and start preventive approaches.

Q:  Clostridium is a key player in the gut and it was not addressed. Is this bug involved in wet litter?

In necrotic enteritis yes, in wet litter it will be a part of the 'bad' microbitoa, not the only

Q: Do in vivo, nutrition models exist to induce inflammation? This would be good for additive evaluation. 

Yes, a lot are described, using poorly digestible substrates, consequently bacterial overgrowth and inflammation

Q:  Why do we use Bacilli as probiotics and not one of key players in gut health?

Because Bacillus genius has shown lots of potential to secrete a large range of metabolites able to influence microbiota, moreover their spore-forming capacity give them the potential to support lots of feed processes.

Q: Climatized vs. Control housing: is the difference in cytokine expression and inflammation due to lower/inconsistent feed intake and disruption within the gastro-intestinal tract? 

Indeed reducing heat load on the animals will reduce inflammation and thus oxidative challenge to the gut barrier.

Q:  Is antibiotic usage in field not a problem for biomarker detection (as it creates a sudden change)? 

Yes, but the aim of biomarkers is to justify antibiotic usage, and when these are used anyway, markers become irrelevant.