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Home / Equine Research Bank / Anim Sci J / Complete Extruded Diet: How Does Equine Fecal Microbiota Cha...
Animal science journal = Nihon chikusan Gakkaiho2026; 97(1); e70147; doi: 10.1111/asj.70147

Complete Extruded Diet: How Does Equine Fecal Microbiota Change During Intake Adaptation?

Abstract: This study aimed to investigate the gradual adaptation of the fecal bacterial community and in vitro fermentative capacity of horses fed a complete extruded diet (CED). Twelve geldings weighing 370 kg were removed from a native pasture and fed coastcross hay (Cynodon spp) for 7 days. In the second week, horses were assigned to two groups: one group was fed exclusively with coastcross hay (HAY) for 28 days and the other group fed with weekly increases of CED (30%, 60%, and 100%) to replace HAY. Fecal samples were collected on Days 7, 14, 21, and 28 for microbiota and in vitro fermentation analyses. CED intake reduces the relative abundance of phyla Fibrobacteres, Proteobacteria, Campilobacterota, Lentisphaerae, and SR1, while increasing Verrucomicrobia and Synergistetes. The fecal bacterial diversity was maintained until Day 21 (60% CED) but declined when hay was completely withdrawn. Equine fecal microbiota is diet-dependent; the stability of microbial diversity is more closely linked to the presence of roughage than to CED intake. Also, the inclusion of CED affects its microbial abundance and the detection of bacterial groups able to alter in vitro fermentative activity.
© 2026 The Author(s). Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.
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Publication Date: 2026-01-08 PubMed ID: 41504615PubMed Central: PMC12782053DOI: 10.1111/asj.70147Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Objective Summary

  • The study examines how the fecal bacterial community and fermentative capacity of horses change as they adapt from a hay-based diet to a complete extruded diet (CED).

Introduction and Research Purpose

  • The research focuses on equine nutritional science, specifically the effects of diet transition on gut microbiota.
  • Understanding gut microbiota adaptation is crucial because it influences digestive health, nutrient absorption, and overall horse well-being.
  • The study aims to monitor fecal microbiota changes and fermentative activity during a gradual switch from coastcross hay (a type of roughage) to a fully extruded pelleted feed called CED.

Experimental Design and Methods

  • Twelve geldings weighing approximately 370 kg were initially kept on native pasture, then transitioned to coastcross hay for 7 days to standardize baseline conditions.
  • In the second week, horses were divided into two feeding groups:
    • HAY group: Continued exclusively on coastcross hay for 28 days.
    • CED group: Fed increasing amounts of CED replacing hay in three stages (30%, 60%, and finally 100%) over the 28-day period.
  • Fecal samples were collected on days 7, 14, 21, and 28 to analyze:
    • Microbiota composition through bacterial community profiling.
    • In vitro fermentative capacity, assessing how the bacterial community contributes to nutrient fermentation.

Key Findings

  • As horses increased CED intake, the relative abundance of certain bacterial phyla such as Fibrobacteres, Proteobacteria, Campilobacterota, Lentisphaerae, and SR1 decreased.
  • Conversely, the abundance of Verrucomicrobia and Synergistetes increased with greater inclusion of CED.
  • Microbial diversity remained stable until Day 21, corresponding to a diet of roughly 60% CED, suggesting resilience in the microbiota up to a moderate replacement level.
  • However, complete removal of hay (100% CED diet) led to a significant decline in fecal bacterial diversity, indicating roughage presence helps maintain a diverse microbial population.

Interpretation and Implications

  • Equine fecal microbiota composition is heavily influenced by diet, particularly the presence or absence of roughage like hay.
  • The findings underscore that microbial community stability is more linked to roughage intake than to the amount of CED itself.
  • Introducing a complete extruded diet shifts the balance of microbial populations, likely affecting the gut’s fermentative environment and nutrient breakdown.
  • The microbial changes might impact digestive efficiency and horse health, making gradual diet transitions and roughage retention important to avoid gut dysbiosis.

Conclusions

  • The study provides valuable insights on how feeding practices affect equine gut health by mapping microbiota adaptations during diet shifts.
  • Complete withdrawal of hay negatively affects microbial diversity, underscoring the importance of roughage in equine diets.
  • Careful management of diet transitions involving pelleted CED can minimize adverse impacts on gut microbiota and fermentative capacity.
  • These findings can help inform feeding strategies to optimize equine gut health and performance.

Cite This Article

APA
Franzan BC, da Silva Coelho I, Ramos EM, de Souza ARP, de Almeida FQ, Silva VP. (2026). Complete Extruded Diet: How Does Equine Fecal Microbiota Change During Intake Adaptation? Anim Sci J, 97(1), e70147. https://doi.org/10.1111/asj.70147

Publication

Animal science journal = Nihon chikusan Gakkaiho
ISSN: 1740-0929
NlmUniqueID: 100956805
Country: Australia
Language: English
Volume: 97
Issue: 1
Pages: e70147
PII: e70147

Researcher Affiliations

Franzan, Bruna Caroline
  • Animal Science Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.
da Silva Coelho, Irene
  • Veterinary Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.
Ramos, Emilly Martins
  • Animal Science Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.
de Souza, Ana Rúbia Pereira
  • Veterinary Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.
de Almeida, Fernando Queiroz
  • Veterinary Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.
Silva, Vinicius Pimentel
  • Animal Science Institute, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil.

MeSH Terms

  • Animals
  • Feces / microbiology
  • Horses / microbiology
  • Horses / physiology
  • Fermentation
  • Diet / veterinary
  • Animal Feed
  • Adaptation, Physiological / physiology
  • Male
  • Animal Nutritional Physiological Phenomena / physiology
  • Eating / physiology
  • Gastrointestinal Microbiome / physiology
  • Microbiota / physiology
  • Time Factors
  • Dietary Fiber

Grant Funding

  • 001 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES

Conflict of Interest Statement

The authors declare no conflicts of interest.

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