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Research Article
The Horse Gut Microbiome Responds in a Highly Individualized Manner to Forage Lignification
Andres Gomez
University of Minnesota
Corresponding Author
ORCiD: https://orcid.org/0000-0002-1174-0368
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Although contributions of the equine gut microbiome to forage utilization are well recognized, the impact of alfalfa lignification on the equine gut microbiome remains unknown. Here, we characterized microbial community dynamics in the equine distal gut when feeding reduced lignin (RL) and reference alfalfa hays (CON-control) ( Medicago sativa L.) to adult stock-type horses. Hay from RL and CON cultivars were similar in crude protein, neutral detergent fiber, and equine digestible energy, but differed in acid detergent lignin content (RL:74 g kg -1 vs. CON: 81 g kg -1 ). Dietary treatments were fed to six horses in a crossover study. Experimental periods consisted of a 9-d dietary adaptation phase followed by a 5-d total fecal collection phase, during which horses were housed in individual box stalls and manure was removed on a continuous 24-h basis. At 12-h intervals, feces were thoroughly mixed, frozen, and used for bacterial community composition analyses via V4, 16S rRNA amplicon MiSeq sequencing.
Results: RL alfalfa did not result in specific fecal microbiome composition across all horses. However, upon incorporating individual horse in the model, it was shown that the microbiome of each subject did respond to hay lignin content in an individualized manner over time, in terms of alpha and beta diversity. Closer inspection of specific taxonomic changes upon feeding the two diets also revealed horse-specific trends, with unique amplicon sequence variants classified as Akkermansia , Fibrobacter succinogenes , Treponema, and Paludibacter fluctuating significantly in abundance when RL alfalfa was fed, depending on horse. Along these lines, horse-specific associations between individual gut microbiome traits and characteristics of the digested CON or RL alfalfa were observed, mainly in regards to dry matter digestibility and mean feed particle size.
Conclusions: These results indicate that the horse gut microbiome responds in an individualized manner to small changes in the amount of acid detergent lignin in alfalfa hay, potentially impacting several feed digestibility characteristics. The implications of horse-specific responses to forage quality in regards to metabolic health and performance remain to be elucidated.
Keywords
Equine, Alfalfa, Reduced lignin, fecal microbiome
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This is a preprint. It has not completed peer review.
Research Article
The Horse Gut Microbiome Responds in a Highly Individualized Manner to Forage Lignification
Andres Gomez
University of Minnesota
Corresponding Author
ORCiD: https://orcid.org/0000-0002-1174-0368
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 11 May, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
General Microbiology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Although contributions of the equine gut microbiome to forage utilization are well recognized, the impact of alfalfa lignification on the equine gut microbiome remains unknown. Here, we characterized microbial community dynamics in the equine distal gut when feeding reduced lignin (RL) and reference alfalfa hays (CON-control) ( Medicago sativa L.) to adult stock-type horses. Hay from RL and CON cultivars were similar in crude protein, neutral detergent fiber, and equine digestible energy, but differed in acid detergent lignin content (RL:74 g kg -1 vs. CON: 81 g kg -1 ). Dietary treatments were fed to six horses in a crossover study. Experimental periods consisted of a 9-d dietary adaptation phase followed by a 5-d total fecal collection phase, during which horses were housed in individual box stalls and manure was removed on a continuous 24-h basis. At 12-h intervals, feces were thoroughly mixed, frozen, and used for bacterial community composition analyses via V4, 16S rRNA amplicon MiSeq sequencing.
Results: RL alfalfa did not result in specific fecal microbiome composition across all horses. However, upon incorporating individual horse in the model, it was shown that the microbiome of each subject did respond to hay lignin content in an individualized manner over time, in terms of alpha and beta diversity. Closer inspection of specific taxonomic changes upon feeding the two diets also revealed horse-specific trends, with unique amplicon sequence variants classified as Akkermansia , Fibrobacter succinogenes , Treponema, and Paludibacter fluctuating significantly in abundance when RL alfalfa was fed, depending on horse. Along these lines, horse-specific associations between individual gut microbiome traits and characteristics of the digested CON or RL alfalfa were observed, mainly in regards to dry matter digestibility and mean feed particle size.
Conclusions: These results indicate that the horse gut microbiome responds in an individualized manner to small changes in the amount of acid detergent lignin in alfalfa hay, potentially impacting several feed digestibility characteristics. The implications of horse-specific responses to forage quality in regards to metabolic health and performance remain to be elucidated.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6