Equine Nutrition 101

HORSES’ UNIQUE DIGESTIVE SYSTEM

To develop a good feeding program, it’s important to understand how the horse’s digestive system works.

Once food is chewed and swallowed, it’s passed down the esophagus into the stomach where the digestive process begins. The stomach acts as a reservoir to keep the small intestine continuously supplied and begins the digestion of protein.

The horse’s stomach is relatively small. Food moves through it quickly. Since horses don’t vomit, over-feeding can cause serious problems, including colic and stomach rupture. As a precaution, horses that need a lot of feed should be fed three or more times a day.

From the stomach, food enters the small intestine where enzymes that digest carbohydrates, fat and protein are secreted. Carbohydrates are turned into glucose and other simple sugars that are absorbed and used for energy. Proteins are broken down into amino acids, which are absorbed and used as building blocks for the body. Bile secreted in the small intestine helps digest fat. Many minerals are absorbed in the small intestine.

In the cecum, large populations of bacteria and other microbes produce enzymes that break down fiber into volatile fatty acids. These fatty acids are then absorbed and used for energy. Bacteria in the cecum also help synthesize many B vitamins and vitamin C.

Because the horse’s cecum is near the end of the digestive tract, horses can’t absorb significant amounts of microbial protein from the cecum. Therefore, good quality protein with adequate amino acids must be provided in the feed.

Some microbial breakdown of fiber continues to occur in the large intestine, but the major activity here is reabsorption of water.

DIGESTIBILITY OF FEEDS

Efficient digestion is influenced by a number of factors. Rolling, cracking or crimping certain grains allow enzymes to work more effectively. Cooking does improve digestibility. Pelleting is a form of cooking, which is why pelleted feeds usually have a higher digestibility than textured feeds.

Feeding large amounts at once can decrease digestibility by increasing rate of passage. The faster food moves through the system, the less time enzymes and bacteria have to act on the feed components. Feeds with high levels of starch have a faster rate of passage than feeds higher in fat and fiber.

NUTRIENTS HORSES NEED

Excluding water, there are four basic nutrient groups: Energy, Protein, Vitamins and Minerals.

Energy is supplied by carbohydrates, protein and fat. Carbohydrates are the primary source of energy. Protein is an inefficient source of energy; carbohydrates and fat are much better.

Protein is mainly used to build body tissues. Any excess is used to supply energy or is stored as fat. Hard work, age and growth all increase the total protein needs of the horse.

Fat is a much more concentrated source of energy than carbohydrates or protein. Vegetable sources of fat supplies the unsaturated fatty acids horses need for healthy skin and coats.

Traditionally, the way to add extra calories has been to feed extra grain, high in carbohydrates. But overfeeding grain can create uncontrolled, “hot” energy, or worse, diarrhea, insulin resistance, founder or even colic. Feeding fat provides supplemental calories without the risks inherent in extra grain.

Nutrient requirements of individual horses depend on several factors. Age decreases the horse’s ability to absorb nutrients, and nutrient production by microbes in the cecum may be compromised. Growth, lactation, activity level and stress increase nutrient needs relative to maintenance levels.

VITAMINS

Vitamins are organic compounds the body needs for normal functioning. The fat soluble vitamins-- A, D and E-- are stored in the body. Excesses of vitamins A and D can be toxic. Water soluble vitamins, including the B vitamins and vitamin C, are flushed out in the urine when the body has more than needed.

Most horses produce all the water-soluble vitamins they need in their cecum, but very young horses who do not have a fully active cecum, sick horses or those recovering from illness or other trauma, and senior horses whose manufacturing and absorption capabilities are diminished, can benefit from daily supplementation. Horses in intense training may also benefit from vitamin supplements.

MINERALS

The amount of minerals each horse needs depends on a variety of factors, including the horse itself. Young horses need higher levels of some minerals than full-grown horses, as do pregnant and lactating mares and horses in intense training.

Bioavailability, or how efficiently an element is absorbed and utilized by the horse, affects the quantity required.

Minerals must be kept in balance. Feeding high levels of one mineral can lead to problems with absorption of another. The best way for horses to get the right balance of minerals is naturally, through a well-balanced nutritional program based on high-quality feeds.