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Rumen microbial communities influence metabolic phenotypes in lambs

This work describes how different historical colonization events induce changes in the rumen microbiota and the host phenotype through time.  It brings new insights on the interactions between gut microbial populations among themselves and with the host and highlights the importance of rumen microbes as modifiers of the host metabolic phenotype.  Basic concepts and some results, i.e. the link between gut Methanomassiliicoccales and urine trimethylamine N-oxide (an atherosclerosis-related metabolite in humans), are of interest for ruminants but are also applicable to other species. 

Agneau.. © INRA, NORMANT Sophie
Updated on 08/01/2017
Published on 08/01/2017

Context and challenge:

The gut microbiota of higher animals provides a myriad of ecosystem services to the host.  An essential process for the proper functioning of the gastrointestinal microbiota is the recruitment and development of their various microbial denizens.  Colonization events such as those induced by different environments are important as they occur during a specific time window and can have a lasting effect on the host animal. 

Historical colonization events are difficult to test on some mammals due to biological constraints and confounding variables such as genotype, maternal transmission and changes in diet, particularly weaning.  We used lambs as animal model because the precocial characteristic of the species allows the separation of lambs from their mothers soon after birth and makes it possible to control the diet and the surrounding environment.  The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of lambs for identifying host-microbe associations and potential biomarkers of digestive function.

Results:

The composition of the rumen bacterial and archaeal communities was monitored concurrently with measures on urine metabolome and other general traits attributed to the capacity of the animal to utilize feeds such as digestibility, ingestion, and live weight gain.  This work brings new insights on the interactions between gut microbial populations among themselves and with the host and highlights the importance of gut microbes as modifiers of the host metabolic phenotype.  This information is expected to help understanding the role of the microbiota in nutrition and health of the host.  We observed that growth in lambs was not affected by a reduced rumen microbial diversity, by the presence or not of protozoa or by a mild stress treatment.  In spite of that, rumen microbial diversity had a major influence on rumen fermentation parameters, digestibility, and the general metabolism of the host.  The latter monitored through the urinary metabolome profile.  These results suggest that under controlled and unchanged sanitary, environmental, and dietary conditions an adequate rumen function can be provided by a microbiota with reduced diversity.  The evolutionary advantages for ruminants to maintain an extremely diverse microbial community in the rumen could be regarded as an insurance against dietary changes and occasional aggressions such as xenobiotics. 

Perspectives:

The interaction found between trimethylamine N-oxide and methanogens from the order Methanomassiliicoccales shows potential of the metabolomics approach for the discovery and monitoring of biomarkers of rumen microbial functions.  The fundamentals and results of this work are not only of interest to scientist working on ruminants but also to a broader scientific audience. 

Contact(s)
Scientific contact(s):

Associated Division(s):
Animal Physiology and Livestock Systems
Associated Centre(s):
Auvergne-Rhône-Alpes

References

Morgavi, D. P., E. Rahahao‐Paris, M. Popova, J. Boccard, K. F. Nielsen, and H. Boudra. 2015. Rumen microbial communities influence metabolic phenotypes in lambs. Front Microbiol 6. 10.3389/fmicb.2015.01060