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: How does laminitis develop with horses that consume lush pasture grass?
By Kathleen Crandell, PhD
Most horse owners recognize that consumption of lush pastures puts some horses at risk of developing pasture-associated laminitis (PAL), a potentially life-threatening condition.
Is this merely the ingestion of high concentrations of water-soluble carbohydrates, such as 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 glucose molecules 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. 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.
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 researchers collected fecal microbes from mares and created cultures of Streptococcus bovis, a prominent bacterium in the equine hindgut that is 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, but S. bovis was perfectly capable of making “copious amounts of lactic acid” from either type of inulin.
To protect horses against pH changes in the large intestine, a time-released hindgut buffer can help maintain a stable hindgut environment.
Kathleen Crandell is an equine nutritionist with Kentucky Equine Research in Versailles, Ky.
Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine).
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.
Click here to read Part 1 of the June 1, 2019 installment: How can I slow down the speed at which my horse consumes feed?