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06November

The Carbohydrate Debate

What is the Buzz about Carbohydrates?

With the buzz going around about carbohydrates being the number one contributor to everything from colic and laminitis to hyperactivity and nervousness, with developmental orthopedic diseases (DOD) and Cushing’s Disease thrown into the mix, are carbohydrates – soluble or insoluble - a help or a hindrance to the equine diet?


While the research points to the benefits of feeding fat and fiber (insoluble carbohydrates) over sugars and starches (soluble carbohydrates), you first would do well to understand the process by which a horse digests food, as the process is the key to the answer.

Understanding Digestion
 
Horses are limited in their ability to absorb nutrients from large quantities of food at one time due to their exceptionally small stomachs; a holdover from their days in the wild. Because they can forage up to 20 hours a day, the stomach needs to process food quickly, between 30 to 90 minutes before passing it on to the small intestine where the majority of the nutrients, including protein, some carbohydrates, and fat are digested, as well as where many essential vitamins and minerals are absorbed. The residual matter and liquids then continue on to the cecum (hind-gut) and large intestine, which digests fiber and the remaining starches and sugars.
 
Understanding Carbohydrates
 
There are six main categories of nutrients necessary to a horse’s survival – water, carbohydrates, protein, fats, vitamins, and minerals. While energy isn’t a category, next to water, almost 90% of a horse’s nutrient intake is required to fulfill this critical requirement, and where both soluble and non-soluble carbohydrates come in.
 
Soluble Carbohydrates (starches and sugars)
 
Soluble carbohydrates are broken down into simple sugars (glucose) from the stomach before traveling to the small intestine where they are eventually absorbed into the blood stream. The hormone, insulin, continues the process by transferring glucose to the liver and muscles where it is stored for utilization on demand. This energy reserve, known as glycogen, is the resource that provides immediate power bursts critical for all horses, but especially horses involved in intense anaerobic sports such as racing. The starch from corn, oats, barley, and molasses are the most common sources of soluble carbohydrates
 
Insoluble Carbohydrates (fiber source, cellulose)
 
Unlike soluble carbohydrates, insoluble carbohydrates are derived from the fiber source, cellulose, which is digested in the cecum and large intestine. Taking 24+ hours to process, insoluble carbohydrates are transformed into volatile fatty acids, which are absorbed and held by the liver as an additional energy source. Forages such as hay, beet pulp, and soybean hulls are the main suppliers of insoluble carbohydrates.
 
Understanding the Relationship between the Two
 
Trouble often starts when feeding excessive amounts of soluble carbohydrates. Because there may not be sufficient time for the starches to be broken down in the stomach before reaching the small intestine, glucose and insulin can flood the blood stream causing metabolic upsets, particularly in the young developing or senior horse, as well as hyper-excitability and behavioral problems across the board. Alternatively, when the starches are not adequately broken down, they enter the cecum and are left to ferment, which is where disorders such as gas colic and founder originate.
 
Insoluble carbohydrates, on the other hand, are fundamental to an efficient digestive system - horses can live on fiber alone, and therefore should not be compromised in an effort to reduce calories in the diet.
 
Research shows that increasing dietary fiber, while at the same time reducing starch and sugar intake will benefit the overall health of horses participating in light to medium performance or pleasure activities. And, when coupled with introducing fat into the diet, deemed the densest form of nutrient energy, it helps to control the rate at which glucose is released into the system; thus, further reducing the risks linked with starch overload.
The Bottom Line
 
Ultimately, there is a place for both types of carbohydrates; however, the focus should be on feeding fiber based forages. If your horse needs additional energy or calories for weight gain, consider a high-quality fat source, i.e. stabilized rice bran or flaxseed, which will not cause a “sugar high” associated with corn or grain based products (soluble carbohydrates). On top of which, fat is known to contribute to a shiny, healthy coat.

Posted in Equine Management