2. Stick with your feeding program.
Frequent or sudden changes in your horse's diet are enough to push him into the colic zone, regardless of what the actual dietary ingredients are. It's that tricky microbial balance again. "If the microbes in the intestines get used to a food that isn't fed in an oversupply, the horse can adapt quite well to his diet," says Nathaniel White II, DVM, of Marion duPont Scott Equine Medical Center in Leesburg, Virginia. "The problem comes if you change the type of food or the amount you feed. Then the microbes are unbalanced and upset."
Sometimes the dietary disruption is purely accidental, as in the case when an owner runs out of his usual hay or grain and feeds a replacement that is quite different. Or the horse may be moved to a stable or region of the country where entirely unaccustomed feedstuffs are used. "Grains have different amounts of starch, protein and molasses--different nutrient profiles," says Duren. "The digestive system needs time to adjust to those different levels."
Horses adapt to new grains and hay all the time, and some can accept major and abrupt changes without any ill effects. But to be on the safe side, convert your horse to different rations gradually over 7 to 10 days. Reductions in ration size or nutrient levels can be made relatively rapidly, in a week or less. But when you're bumping horses up to higher-powered diets involving more carbohydrates, fat and/or protein, take at least 10 days of incremental increases to give the intestinal bacteria time to acclimate to the new diet.
When upping a horse's ration, suggests Kathleen Crandell, PhD, of Kentucky Equine Research, Inc., begin by mixing one-quarter portion of the new grain with three-quarters of the old grain for two days. Continue to increase the new grain in the ration by a quarter every two to three days until the new feed completely replaces the old grain. Crandell recommends a similar stepwise process when switching hay. Horses who are accustomed to eating low-protein, moderate quality grass hay and are switched suddenly to a legume, such as alfalfa, often experience some degree of digestive disturbance.
3. With grain, think small and often.
The human dietary schedule of three meals a day--or even fewer for those on the run--is a ritual that fits our carnivorous needs. You gobble down a substantial meal, which lingers in your rather large stomach, and digest it over the course of the day.
Horses, on the other hand, are continual foraging machines. When left on pasture and to their own devices, horses pick and choose their mouthfuls here and mouthfuls there for as many as 20 hours a day. These bite-size portions remain in the stomach for less than two hours and in the small intestine for about an hour, then spend from several hours to a couple days getting the full digestive treatment in the large intestine. In all, an average horse ration takes anywhere from 12 to 36 hours to run its course through the gut. Coarse or dense fibers may spend as long as seven days undergoing the digestive efforts of the intestinal microbes.
Unfortunately, our meat-eating mealtime schedule can wreak havoc on our horses' vegetarian setup. We'll dump a few scoops of grain in the feed tub a couple times a day, not realizing that these feeding practices put a real strain on horses' digestive equipment. "The horse's stomach has only about a five-gallon capacity, so five pounds of grain is pretty much the maximum to feed at one time," says Crandell. "If you give your horse more, he can eat it, but the grains aren't broken down or adequately prepared for proper digestion."
A more gut-friendly option is to feed smaller, equal-size portions often, at the same times throughout each day, allowing slow and steady digestive action. Not only do smaller portions aid the digestive process, but the presence of food in the stomach keeps acid levels lower and the horse better hydrated. "When a horse gets a bolus, a mass of chewed food, as is common with twice daily feeding, the rapid production of fatty acids draws water into the colon," says White. "When the body senses the dehydration it draws the water back into the bloodstream. That process can first dehydrate the blood and subsequently the colon."
4. Keep him moving.
What goes on outside your horse can affect his inner functions to a remarkable degree, giving your management routines a major role in gut health. Take the lead from the way your horse would voluntarily structure his day: spending most of his time grazing and ambling about.
Over and over, research studies of predisposing factors in colic cases find that horses who spend the greatest part of the day standing in stalls are much more prone to abdominal disease than those who live in turnout situations. Turnout with compatible companions keeps horses happy, allows them social interaction and gives them the opportunity to let off some steam in addition to consuming their favorite food. Not only is the horse free to consume the ideal fibrous diet, but the simple, continual act of stepping to reach one bite, then the next and the next keeps the food sloshing along in the gut and is believed to increase intestinal motility.
"Peristalsis, the contraction of the intestinal wall, carries the food through to the next portion of the gut," says Harman. "The horse's motion keeps a tone to that whole system." Even if your horse lives in a situation where he can't enjoy continual turnout, be diligent in seeing that he gets daily exercise. Light to moderate controlled exercise in a paddock, on the longe line or under saddle contributes to better digestion.