title: High nutrient availability reduces the diversity and stability of the equine caecal microbiota.
abstract: BACKGROUND
  It is well known that nutrient availability can alter the gut microbiota composition, while the effect on diversity and temporal stability remains largely unknown.
  
  
  METHODS
  Here we address the equine caecal microbiota temporal stability, diversity, and functionality in response to diets with different levels of nutrient availability. Hay (low and slower nutrient availability) versus a mixture of hay and whole oats (high and more rapid nutrient availability) were used as experimental diets.
  
  
  RESULTS
  We found major effects on the microbiota despite that the caecal pH was far from sub-clinical acidosis. We found that the low nutrient availability diet was associated with a higher level of both diversity and temporal stability of the caecal microbiota than the high nutrient availability diet. These observations concur with general ecological theories, suggesting a stabilising effect of biological diversity and that high nutrient availability has a destabilising effect through reduced diversity.
  
  
  CONCLUSIONS
  Nutrient availability does not only change the composition but also the ecology of the caecal microbiota.
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Naja C K
authors.initials: NC
authors.lastname: Hansen
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Avershina
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Liv T
authors.initials: LT
authors.lastname: Mydland
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Næsset
authors.affiliation: Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Aas, Norway.
authors.forename: Dag
authors.initials: D
authors.lastname: Austbø
authors.affiliation: Nofima, The Norwegian Institute of Food, Fisheries and Aquaculture Research, Aas, Norway.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Moen
authors.affiliation: Nofima, The Norwegian Institute of Food, Fisheries and Aquaculture Research, Aas, Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Måge
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway; knut.rudi@nmbu.no.
authors.forename: Knut
authors.initials: K
authors.lastname: Rudi
keywords: 16S rDNA; caecal microbiota; equine; hay; whole oats