Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find Part 2 of the latest question and answer installment that you can share with your footcare clients.
Q: What role do fructans play in laminitis situations?
By Kentucky Equine Research staff
A: Most horse owners already know that consumption of lush pastures puts some horses at risk of developing pasture-associated laminitis(PAL), a potentially life-threatening condition.
Several questions need to be asked when PAL is a possible concern:
- Is it merely the ingestion of high concentration of water-soluble carbohydrates, like simple sugars?
- Does a horse’s reduced sensitivity to insulin also impact PAL?
- Is it a combination of these factors or even something completely different?
Without an improved understanding of the underlying events leading up to PAL, controlling this condition remains challenging.
One theory is that a specific type of water-soluble carbohydrate, called fructan, can lead to PAL. Fructans are chains of fructose sugar molecules that are configured much like starch, which is made up of glucose molecules that are linked together.
Unlike starch, ingested fructans are minimally digested in the small intestine before entering the large intestine. Once in the hindgut, fructans are fermented by bacteria, primarily Streptococcus spp., to produce lactic acid. While the horse may eventually use lactic acid for energy, this is much different than the fermentation of fiber, which produces short-chain fatty acids that provide energy for the horse without affecting the pH.
“An increase in lactic acid produced by fermenting fructans decreases the pH of the large intestine, causing hindgut acidosis,” says Kathleen Crandell, an equine nutritionist with Kentucky Equine Research. “This makes the walls of the intestine leaky, allowing endotoxins produced by bacteria, amines and proteinases to be absorbed into the bloodstream and circulate to the hoof, potentially causing laminitis.”
There are several types of fructans, and it is not clear if all fructans are fermented in the same way and are equally dangerous. To better understand the impact of fructans on PAL, researchers* created a model of the large intestine to measure the fermentation of a specific type of fructan called inulin.
More specifically, the research group collected fecal microbes from mares and created cultures of Streptococcus bovis, a prominent bacterium found in the equine hindgut suspected of fermenting fructans. Both short-chain inulin (with less than 10 fructose molecules making up the inulin) and long-chain inulin (with more than 23 fructose molecules) were incubated with the fecal microbes and S. bovis.
Short-chain inulin was more readily fermented than long-chain inulin in these models, but S. bovis was perfectly capable of making “copious amounts of lactic acid” from either inulin type. This research contributes to our understanding of PAL, a complex and multifactorial condition.
To protect horses against deleterious pH changes in the large intestine, Crandell says feeding a time-released hindgut buffer helps maintain a stable hindgut environment.
*Harlow, B.E., I.A. Kagan, L.M. Lawrence, et al. Effects on inulin chain length on fermentation by equine fecal bacteria and Streptococcus bovis. Journal of Equine Veterinary Science. In press.
Located in Versailles, Ky., Kentucky Equine Research is an international research, consulting and product development firm working in the areas of equine nutrition and sports medicine.
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Click here to read Part 1 of the July 1, 2016 installment: Can nutrition help in preventing or treating thrush?
Click here to read more installments of Hoof Nutrition Intelligence.