A horses digestive system is made up of (in order) the mouth and esophagus, the stomach, the small intestine, the caecum, the colon (or large intestine), and the rectum. This system is designed to digest a constant supply of small amounts of high-fiber feed throughout the day.
With an ideal diet, a horse’s digestion begins in the mouth as food is chewed and mixed with saliva then swallowed. The feed then passes down the esophagus to the stomach, which in a horse is small and acidic and begins to absorb the most easily digestible components of the feed, such as simple sugars and starches (carbohydrates). Absorption of carbohydrates continues in the small intestine, along with the absorption of most proteins. What reaches the caecum and colon, together referred to as the “hind gut”, is mostly fiber.
The fiber that reaches the hind gut is then fermented by the beneficial bacteria and other microbes that inhabit the hind gut of the horse. This is why horses are referred to as “hind gut fermenters.” This fermentation process further breaks down the fiber, extracting as much nutrition as possible, before it passes out of the hind gut and into the rectum to be eliminated from the horse.
The hind gut is also where a variety of critical vitamins are synthesized, including many of the B-complex vitamins. In addition, a healthy microbial community in the hind gut prevents less desirable microbes from taking hold within a horse, keeping the immune system healthy and effective. It is difficult to overstate the importance of a healthy hind gut, and many equine nutritionists and veterinarians point out that proper health and nutrition for horses start with a healthy gut.
The problem we face today is that horses’ diets, or at least the way we feed horses, is most often less than ideal. Modern domestic horses tend to be fed only a few times a day, forcing them to consume large amounts of feed in a short period of time, versus small amounts of feed over a longer period of time. If the feed is a high-fiber forage, however, like hay, most horses adapt to this type of feeding quite well. But when we add grain and other high-sugar and high-starch feeds and feed concentrates to a horse’s diet, we start to cause problems for the horse.
Here’s what happens:
When we feed too much high-sugar or high-starch feed to a horse, the stomach and small intestine are not able to adequately absorb the carbohydrates. These carbohydrates then pass to the hind gut, where the fermentation process turns them into lactic acid. This lowers the pH of the hind gut, making it more acidic, and therefore a less desirable environment for the beneficial bacteria that are designed to break down fiber, not carbohydrates.
Some of the effects of this “hind gut acidosis” can be:
- More lactic acid passing to the muscles, meaning more soreness and longer recovery times after hard work
- Tying up
- Hind gut ulcers
- Laminitis or “Founder”
- Decreased beneficial microbial activity, leading to poor feed conversion
- Infiltration of the gut by undesirable pathogens, leading to a weaker immune system, more illness, and increasing gut health issues
Even though forages do have some nutritional deficiencies, in the vast majority of cases, a healthy horse will thrive on a forage-only diet, made up of the best quality hay available and a vitamin and mineral supplement designed specifically to fill the nutritional gaps in the forage.
Dr. Thornley’s™ Hay Balancer™ provides a simple and economical way to make sure your horse receives the important nutrients that are often deficient in forage, without adding unnecessary carbohydrates that can cause hind gut acidosis. In addition, Hay Balancer™ also provides proven prebiotics that act as food for the beneficial microbes in a horse’s hind gut, promoting increased feed conversion and better overall health.