Understanding Energy - Key Part Of Feeding Horses Correctly
By Donald Stotts
STILLWATER - Most horse owners know first-hand that problems can occur when over-eating certain types of food, but this fact sometimes is overlooked when applying it to horses rather than themselves.
One of the major causes of digestive upset in horses is caused by over-consumption of energy-containing compounds in the diet, said Dave Freeman, Oklahoma Cooperative Extension Service equine specialist.
"This happens most frequently when horses are fed large amounts of carbohydrates at a single meal," Freeman said. "Understanding how energy is supplied by different nutrients, and how to manage the feeding of energy, can help horse managers develop feeding plans that reduce the incidence of colic and founder."
Energy is the fuel for chemical reactions that run the various systems of the body. Energy-containing compounds are parts of grains, forages and many supplements. The main sources of energy are supplied in the form of carbohydrates (starch), fat, fiber and protein.
Starch is found primarily in grains, and as much as 55 percent to 85 percent of starch is absorbed in the small intestine. Starch bypassing to the cecum and large intestine is digested by microbes and absorbed as volatile fatty acids. "Large amounts of starch presented to the cecum and large intestine predispose horses to colic because of gaseous products of microbial digestion, and abnormal changes in gut pH and fluid balance," Freeman said.
The amount of starch bypassing the small intestine to the hindgut depends on intake level, rate of flow through the digestive tract and the amount of mechanical disruption of the hard seed coats of grains.
"Considering starch levels in typical grain mixes, recommendations are to split daily grain needs into two daily feedings when grain levels are greater than 0.5 percent of body weight per day," Freeman said.
This works out to five to six pounds of grain for a 1,000-pound horse. Small particle size (ground mixes) may further increase starch bypass because ground feed passes more quickly than textured or coarsely processed grain.
While planning for starch levels is important, fat is another component of most feedstuffs that needs to be taken into account. Unsupplemented grain mixes typically have minimums of two percent to three percent fat. Fat is higher in energy than starch, fiber or protein. "Adding additional levels of fat in formulations for grain mixes has become a common practice," Freeman said. "This supplementation increases the energy
concentration of grain mixes without increasing the amount of starch."
Freeman said fat-added feeds have advantages of being more concentrated in energy, and safer by containing less starch as a total part of the energy-containing compounds. "Fat-added feeds may contain eight percent to 10 percent total fat," he said. "Horses can efficiently digest energy in fat at these levels."
While horses easily digest fat at levels commonly found in formulated feeds, they do not easily digest all sources of fiber. Fiber digestion is dependent on the efficiency of digestion from microbial fermentation in the cecum and colon. "Horses don't digest low-quality forages as well as cattle, thus they need to eat immature, high-quality hay or pasture," Freeman said.
In addition to supplying energy, dietary fiber helps regulate the flow of nutrients in the digestive tract, and guards against behavioral problems related to boredom. "General recommendations are to supply hay or pasture at minimums of 0.75 percent of body weight per day," Freeman said. "The only nutritional problem to feeding high-quality forage as the sole source of feed is that some classes of horses need more energy than an all-forage diet can supply,"
Finally, protein is an important consideration in most feedstuffs. The main purpose of feeding protein is for the horse's body to use various amino acids to make or maintain protein-containing substances such as muscle, enzymes and hormones.
"Protein also is used as a source of energy, although prioritizing protein as a fuel source rather than its main purpose is nutritionally inefficient," Freeman said.
One point to remember is that many commercial feeds with high protein are formulated to also have higher concentrations of starch and fat. "Horse managers must take into account the numerous combinations of starch, fat, fiber and protein levels possible through different feeding practices," Freeman said. "These combinations and their potential effects are why feeding recommendations for horses are based in part on supplying energy safely."
We would like to take this opportunity to thank Oklahoma State University for allowing us to provide you with this information.
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