Digestion involves extracting nutrients from a food base by breaking the food down into its component parts and absorbing them. But there’s one major nutrient source that no animal can break down – fiber.
A few species of microbes can produce the enzymes needed to break fiber down into metabolisable units. This means herbivores have had to evolve specialized compartments to house those micro-organisms and “harvest” their fermentation products. For the cow, it is a two-compartment section of a fourstomach adaptation. But the horse has ignored the stomach in favor of a large-volume hindgut.
Breaking Down Digestion
Carbohydrates are the major source of energy for the horse. It is purely down to the bond between different sugar molecules that determines whether or not the carbohydrate is a fiber or saccharide. For example, alpha-linked glucose builds into starch, and beta-linked glucose builds into cellulose. The beta link tends to twist the sugar molecules, which means animal enzymes cannot break them; but those few microbial species mentioned above have enzymes that can. The products of this breakdown fuel the fermentative processes of other microbes, so a whole interdependency of microbial species is created.
These end products (acetate, etc., the volatile fatty acids) are small enough to be absorbed across the hindgut wall, where they can enter the metabolic chain for sugars and produce energy.
Larger molecules, such as amino acids, sugars derived from the enzymic breakdown of protein, and starch, are absorbed in the small intestine and carried away for metabolism, growth and normal biochemical activity. If the levels of major nutrients are too high, the horse’s ability to break down and absorb them is compromised and macronutrients can escape into the hindgut.
The Hindgut’s Role
The hindgut has a different environment than the small intestine – it’s less acidic and harbors a different mix of microbes. Macronutrients flooding this area (complete with bacteria that use those nutrients) disrupt the balance, shifting it away from fiber fermentation and generating endotoxins such as nitrites and amines from protein, and high levels of lactate from starch. These effects may also make the environment more acidic, causing death and decomposition of the native micropopulation.
The Importance of Proper Nutrition
In extreme cases, absorbing these toxins will have negative effects on health, highlighting the need for correct feeding. As a species, the horse has evolved from a plains inhabitant living off poor quality herbage, and we are now in a world where overfeeding is commonplace. This is why there has been an upsurge in nutritional aids, to improve the digestion of nutrients so they are utilised where they should be and don’t disrupt the microbial spectrum along the gut.
Emerald Valley provides additional enzymes so protein and starch is broken down before it leaves the small intestine; natural products to combat wear and tear; and pre- and pro-biotics to bolster and support microbial populations and produce nutrients that enforce gut integrity and immune function. This helps horses better utilize what they are eating, and heads off feed-related issues such as obesity, insulin resistance, and laminitis.
Dr. Tom Shurlock started working for British Horse Feeds in 1997. Armed with a BSc in Agricultural Biochemistry & Nutrition and also a PhD in Animal Physiology & Nutrition, it was very clear from the get go that researching new developments in horse nutrition is Tom’s passion.
Emerald Valley met Dr. Tom in 2003 when an interest in finding natural low sugar/low starch feeds for horses struggling with metabolic issues led them to import Speedi-Beet and Fibre-Beet, both made by British Horse Feeds. Emeraldvalleyequine.com