Beginning to Understand Your Horse's Nutritional Needs:

Horses are a rather unique animal as they are designed to eat small amounts all day long. In the wild, horses spend most of their day grazing, eating small amounts of grasses, leaves, bark and shrubs. This is the way horses were designed to eat. In order to understand how to properly feed your horse you need to understand how he processes what you feed him.

Once chewed, feed travels down approximately four feet of esophagus and into the stomach. A horse's stomach is relatively small when compared to the rest of the horse, holding only about two gallons (eight quarts). Little digestion takes place in the stomach and food can pass to the small intestine in as little as fifteen minutes (liquids and easily digestible feeds). Which is why horses always seem to be hungry; they are! What little digestion does take place in the stomach is done mostly by digestive enzymes produced by the pancreas. Enzymes are simply proteins which produce chemical changes in organic matter (feed), which causes the feed to break down.

Enzymes are also the main digestive mechanism in the small intestine, which is the next step in the digestive process. The small intestine is about 70 feet long and holds around 12 gallons (48 quarts). Feed takes about one hour to move through the small intestine. Over 50% of the digestion of crude proteins and easily dissolved carbohydrates takes place between the stomach and small intestine which together make up the fore gut. Fibrous materials (hay) are digested later, in the hind gut.

The next step for your horse's now partially digested feed is the Cecum, a four foot long 'sack' which holds about 10 gallons (40 quarts). Here, the process of digestion changes. Where the fore gut digested with enzymes, the hind gut, which begins with the Cecum, uses primarily specialized microbes. These microbes develop depending on what the horse is eating. The anatomy of the Cecum is unique with both the entrance and exit of the organ on top and located only inches apart. Feed spends about seven hours in the Cecum where the feed that was not broken down in the fore gut is broken down and digestion continues.

At twelve feet long the large intestine is not the longest organ in the digestive system but it does have the greatest capacity at 20 gallons (80 quarts) and feedstuffs take 2 to 2.5 days to move through. Microbial digestion continues and much of the nutrients made by microbial digestion are absorbed here. This is the last stage of the journey where feed is turned into balls of manure, passed into the rectum and expelled, leaving us to come though with muck rake and wheel barrow to clean up the mess!

It should be noted that times of digestion will vary from horse to horse; be influenced by the physical condition of the individual horse, stress levels and how long the horse has gone between feedings. The longer the interval between feedings, the longer it will take for the horse's digestive system to begin functioning properly. In some cases, if the horse has gone a long time between feedings it could take 24 hours just for the stomach to clear.

To refresh my memory of the exact capacities, lengths of organs and exactly what is digested where, I went to one of my favorite resources: http://ohioline.osu.edu/b762/b762_5.html