Equine digestion is largely based on microbial fermentation in the large intestine, where dietary fibers serve as key energy sources for gut microbes. Fermentable fibers used in feeding, such as inulin, have attracted interest because of their effects on the intestinal environment and microbial activity.
In this article, inulin is examined in light of the research literature, focusing on its structural properties, fermentability, and its role as part of an overall feeding program.
What Is Inulin?
Inulin belongs to fructans, which are indigestible carbohydrates found in plants. The horse's digestive enzymes do not break down inulin in the small intestine. Instead, it passes into the large intestine, where it serves as a food source for microbes.
In the research literature, inulin is described as:
- a fermentable dietary fiber
- a prebiotic carbohydrate
- part of the nutritional environment of the gut microbiome
(Gibson & Roberfroid, 2008)
Inulin and the Gut Microbiome
In several studies, inulin has been examined because of its connection to the composition and activity of the gut microbiome. As a prebiotic fiber, inulin functions as a substrate—meaning a source of nourishment—for gut microbes or microbial enzymes, especially in the large intestine.
Equine research has found that:
- inulin is fermented in the large intestine
- fermentation produces short-chain fatty acids
- effects depend on the overall diet and the dosing strategy
(Costa et al., 2012; Cooke, 2023)
Inulin Fermentation in the Equine Digestive Tract
Bachmann et al. (2021) investigated the degradation of inulin and FOS compounds in the equine digestive tract. The study found that fructans:
- do not break down significantly in the stomach
- are fermented mainly in the large intestine
- influence gas production depending on the dose and the adaptation period to the feeding program
In addition, Bachmann et al. (2020) showed in their in vitro study that inulin's fermentation activity varies between different sections of the digestive tract. This highlights the importance of dosing and the overall feeding strategy.
Inulin as Part of a Feeding Strategy
In the research literature, inulin is not viewed as a standalone solution. Instead, it is considered part of a broader feeding strategy that takes into account:
- the horse's base diet
- the total amount of fiber
- the balance of fermentable carbohydrates
- the adaptation period
Cooke (2023) emphasizes in a narrative review that the use of prebiotics in horses is based on a nutritional approach, not a medical intervention.
Summary
Inulin is a fermentable dietary fiber whose relevance in equine feeding is linked to nutritional support of the gut microbiome and to fermentation processes in the large intestine.
When gut microbes ferment fibers (such as inulin), the short-chain fatty acids produced serve as energy for the mucosal cells of the large intestine and are part of normal intestinal metabolism.
Based on studies, inulin's effects depend on dosage, the overall feeding program, and the horse's adaptation to the use of fermentable fibers.
References:
- Gibson, G. R. & Roberfroid, M. B. (2008). Prebiotic effects of inulin and oligofructose. Journal of Nutrition.
- Cooke, C. G. (2023). Prebiotics and Synbiotics in Equine Health and Disease. Narrative review.
- Bachmann, M. et al. (2021). Degradation of monosaccharides, disaccharides, and fructans in the stomach of horses adapted to a prebiotic dose of FOS and inulin. Journal of Equine Veterinary Science.
- Bachmann, M. et al. (2020). In vitro gas production from batch cultures of stomach and hindgut digesta of horses adapted to FOS and inulin. Journal of Equine Veterinary Science.
- Costa, M. C. et al. (2012). Effects of diet on the equine hindgut microbiome.Equine Veterinary Journal.
