High nutrient availability reduces the diversity and stability of the equine caecal microbiota

Abstract

BackgroundIt is well known that nutrient availability can alter the gut microbiota composition, while the effect on diversity and temporal stability remains largely unknown.MethodsHere 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.ResultsWe 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.ConclusionNutrient availability does not only change the composition but also the ecology of the caecal microbiota.

Dietary composition and yeast/microalgae combination supplementation modulate the microbial ecosystem in the caecum, colon and faeces of horses

“…When horses changed from a 100 % hay diet to a 56/44 hay/barley diet, their hindgut microbial ecosystems were clearly challenged in terms of diversity and function. The hay/barley diet was associated with a lower bacterial diversity both in the caecum and RV colon in agreement with a previous study (46) and with a lower richness in the caecum only. A lack of sufficient diversity in the bacterial community has been reported to diminish its stability and ability to withstand perturbation (47) .…”

Diet-Dependent Modular Dynamic Interactions of the Equine Cecal Microbiota

“…The feeding of a high fiber diet was previously shown to result in greater microbial stability and reductions in lactic acid-producing bacteria and Streptococcus spp. in feces than in horses fed starch-rich concentrate (10, 41). A stable hindgut environment is crucial for the health of horses, and imbalances in the gut microbiota and fermentation products may lead to diseases such as colic (13) and laminitis (8, 27, 28).…”

Beeinflussung der equinen Mikrobiota durch Fütterung und Probiotika: aktueller Stand der Forschung und rechtliche Grundlagen

“…Studien, in denen mittels Sequenzierung der Einfluss einer stärkereichen Fütterung im Chymus von Zäkum und Kolon untersucht wurde, ergaben, dass bei stärkereicher Fütterung die Diversität der bakteriellen Mikrobiota abnimmt [32] [45]. Außerdem wurde ein Anstieg der laktatproduzierenden und stärkeverwertenden Bacillus-Lactobacillus-Streptokokkus-Gruppe festgestellt, während das zellulolytische Genus Fibrobacter seltener vorkam [13].…”

“…So führt beispielsweise eine stärkereiche Fütterung zu einem Anstieg von Bakterien, die Stärke verwerten und Laktat produzieren [15] [25] [31] [40], während die Anzahl der für die Faserverdauung zuständigen zellulolytischen Bakterien sinkt [15] [31] [40] [43] [45]. Dadurch kommt es zu einem Anstieg der Laktatund SCFA-Konzentration sowie zum Abfall des pH-Werts im Dickdarmchymus [25] [32]. Änderungen in der Zusammensetzung dieser komplexen Mikrobiota werden auch bei Erkrankungen wie Kolik [79], Hufrehe [72], Kolitis [9], Grass Sickness [47] und Durchfall [68] beobachtet.…”