To determine an optimum feeding program for your horse you need to identify what his current condition is and if he has any incidental problems that could affect his digestion. Does he have parasites? Do his teeth need floated? These issues should be dealt with as they arise, or be managed routinely, as in a rotating worming schedule.
His age and activity level will influence what his nutritional needs are. His environment will also have bearing on how you feed. A horse in adequate pasture will not require as much hay per year as a horse that is stabled year round.
You will want to understand the horse's digastive system before you calculate his feeding requirements.
The horse is a nonruminant herbivore. This means that he has a single stomach, and that he eats plants. There are several organs used in the digestive process.
In the mouth his feed is chewed and mixed with saliva to form a bolus which is swallowed and goes into the esophagus. A horse will produce up to 10 gallons of saliva a day! If there is a problem with chewing, such as improper bite or sharp points on his molars that prevent effective chewing, he could have inadequate digestion. These problems could cause the bolus that is swallowed to have less nutritional value, or could even result in colic.
The esophagus is the muscular tube that delivers the bolus of food to the stomach. There is a cardiac sphincter valve leading into the stomach. It is very strong, and prevents food from going back into the esophagus. For that reason, it is almost impossible for a horse to vomit. His stomach will usually rupture if he is overfed and unable to vomit as other animals can.
The stomach makes up only 10% of the digestive system. It is small, and designed for handling small amounts frequently. Ideally, horses would be fed several times a day in small amounts, but that is not always practically possible. Domestic horses are usually fed concentrated feed twice a day, which makes for less than optimum digestion capabilities. If a horse is overfed, or there is a drastic change in feed, it could cause fermentation and a build up of high levels of lactic acid, then paralyzing the pyloric sphincter which lets the food go into the small intestine. In this case the stomach could rupture.
The next step in the process, the small intestine, is where most of the use of nutrition takes place. It is about 70 feet long and can hold around 48 quarts. The food that has started digesting in the stomach enters the small intestine. The nutrients are absorbed into the walls of the small intestine, then the blood stream carries the nutrients to all parts of the body.
Anything remaining undigested then enters the cecum. It is a storage sack about 4 feet long and will hold 40 quarts of food and fluid. It has microbes that break down food that wasn't previously digested. Adequate water is necessary for the proper function of the cecum. Also, the microbes are specific to whatever feed the horse is accustomed to. So if there is a change in feed it should take place slowly, over a three week period as described below. It gives the microbes time to adjust and work on the changes in the feed. Feed remains in the cecum for about 7 hours. The microbes will break it down and produce vitamin K, B-complex, proteins, and fatty acids. The vitamins and fatty acids will be absorbed, but little if any protein will.
The colon, or large intestine is about 12 feet long and will hold 80 quarts. Food will reach here in as little as 7 hours and remain for 48 to 65 hours. Here, microbial digestion continues, and additional nutrients and water are absorbed. Here is where fecal material is formed, then passes through the rectum.
To make a change in your feed follow the following schedule:
Week 1: Feed a mix of three-fourths of the old ration and one-fourth of the new ration.
Week 2: Feed a mix of one-half of the old ration and one-half of the new ration.
Week 3: Feed a mix of one-fourth of the old ration and three-fourths of the new ration.
Week 4: Feed all new ration.
This web page summarizes horse digestion based on information from Ohio State University. The link to your left will take you to the full story. Go there for more details.
