Perhaps you've never thought about why your horse's grain looks the way it does, whether it's a molasses-bathed mix of cracked corn and crimped oats, alfalfa-enriched pellets, or chunky nuggets. If you're like most modern humans, you're accustomed to buying prepared and processed foods for yourself--from fast food meals on the fly to the pre-made soups and sauces on your grocer's shelves.
But while these human foods are typically geared toward saving time, most processing in the horse feed industry has a more fundamental purpose--ensuring that your horse gets the maximum health benefits from the grain he consumes. In this article, we'll look at the main processing techniques used on equine feed, so you'll not only better understand why that grain looks the way it does, but also know what that means to your horse's well-being.
To best understand feed-processing techniques and their importance, it helps to understand a bit about the equine digestive system. As you know, the horse is designed to simply graze the day away. So, the equine gastrointestinal tract--small intestine, large intestine, and cecum--is adept at processing a near-continuous stream of high-fiber forage. But it's not good at handling low-fiber, high-carb meals; in other words, grain in its natural state.
Specifically, while the horse's small intestine digests starch, it can only process a limited amount at a time. (Starch is the major component of grain; it and sugar comprise grain's carbohydrate load.) Any starch not digested in the small intestine travels to the hindgut (large intestine and cecum), and that's where trouble can arise.
"The hindgut is beautifully designed to digest fiber," explains Randel Raub, PhD, director of horse research and new product development for Purina Mills. But if the hindgut is overwhelmed with a large amount of undigested starch, digestive upset can occur, leading to excess gas buildup, cecal or colonic acidosis, diarrhea, lactate accumulation, colic, or laminitis. In large part, this is where and why feed processing enters the picture, as a way to minimize the amount of starch in the horse's diet and/or increase the pre-cecal (mouth through small intestine) digestibility of the starch he does ingest.
The most basic form of grain processing is mechanical. Through such actions as crimping, cracking, rolling, flaking, and dehulling, mechanical processing breaks the grain's outer shell (the seed coat or hull). This makes the starch inside more accessible and more easily digested by the small intestine. The tactic is particularly helpful to older horses which, because of worn teeth and age-related digestive inefficiencies, need a helping hand to fully digest and utilize their feed, says Martin Adams, PhD, equine nutritionist for Southern States Cooperative, makers of the Triple Crown and Legend brand horse feeds.
Mechanical processing is primarily used on hard-kernel grains such as corn, barley, and wheat. Oats are sometimes processed this way. However, oats are fairly soft and their starch is more readily digestible by the horse's small intestine, so processing is typically not considered necessary.
Adams notes that crimped oats are about 2% more digestible than whole oats if you consider only pre-cecal digestibility, that is, digestion only to the small intestine. But if you consider the total digestive tract, there is no difference in digestibility between whole and crimped oats. For corn--which has a higher and less digestible starch content than oats--cracking or grinding increases digestibility greatly.
Mechanical processing has a few disadvantages compared to whole grains. Most significantly, when you break the seed coat, you eliminate some natural protection. This exposes the seed to mold, mycotoxins (toxins from plant molds), microorganisms, and insects, and it decreases the grain's shelf life by hastening nutrient breakdown and oxidation. However, notes Raub, feed manufacturers can take measures that help guard against these problems, such as establishing quality control programs and placing easy-to-read date codes on feed bags. Good barn management practices (i.e., keeping grain in a cool, dry, insect-proof place) can also help.
Turn Up the Heat
A step beyond mechanical processing is thermal processing, which uses heat to "pre-digest" grain. The heat works like natural digestive enzymes to "gelatinize" the grain--that is, break the starchy bonds, making the energy more available for absorption in the small intestine.
Steaming and micronizing are two forms of thermal processing. Steaming uses wet heat to soften the starch bonds. Micronizing uses dry heat (microwaves) for the same result. Studies have shown that protein utilization increases 2-3% in oats and barley when they are micronized. However, says Adams, moist heat is better, since it does a more thorough job of gelatinizing the grain. Plus, he adds, "Micronizing is more expensive and is hardly ever done in commercial horse feeds." On the other hand, oats might be steam-crimped, barley could be steam-flaked, and corn sometimes is steam-rolled or steam-flaked.
Pull It All Together
Pelleting is a more complex form of heat processing. It involves grinding the grain (and/or hay) into particles, mixing and compacting those particles, then "conditioning" them with forced steam and heat at 150-200ï¿½ F. The mix is then forced through a die to create pellets. After cooling and drying, the end product has less than 15.5% moisture--a figure low enough to help the pellets remain hard and to discourage mold.
Adams explains that reducing particle size through grinding increases the surface area of the grain. This, in turn, increases the gelatinization and digestibility of the feed. Some horse feeds combine all ingredients into pellets, while others are so-called textured feeds (i.e., sweet feeds) that mix processed grains, pellets, and molasses. "You need pellets in textured feed, as that is where you put the vitamins, minerals, yeast culture, etc.," says Adams.
Like previously discussed techniques, pelleting makes grain starches more readily digestible by the horse's small intestine. In addition, agree Raub and Adams, the process lends more uniformity to the feed, letting manufacturers easily add and evenly distribute ingredients, ensuring a balanced ration in every bite. Pelleting can also let a manufacturer use products such as dried beet pulp, soy hulls, or wheat mids to enhance a feed's nutritional value, says Raub.
Pellets tend to be less dusty than loose grain or hay and, because they're denser, they take up less storage space. "Pelleting also helps prevent the horse from sorting or separating out individual ingredients," says Raub. That helps ensure your horse gets the feed he needs and you don't pay for grain that's wasted on the stall floor.
Pellets soften in water, so they're easier for young horses, geriatrics, and equines with dental problems to chew and digest. Studies indicate that hay pellets might reduce intestinal fill, giving your horse a trimmer appearance than if he were on a hay diet. Horses might eat 20-30% more hay pellets by weight than actual hay, providing a safe way to give hard keepers and high performers the feed they need.
On the downside, pellets can be eaten faster than loose grain or hay. When used as a hay/forage replacement, they can leave the horse with free time that might result in bad chewing behaviors (i.e., nibbling on your fences). There is also some debate over whether the faster consumption rate might increase the risk of choke and colic.
With pellets, you can't assess the quality of the individual ingredients and have to rely on the manufacturer. Finally, because of the more extensive production process, pellets tend to cost more than the less-processed or unprocessed grains.
"Sweet feeds were the first commercial feeds made for horses, mixing oats, corn, and molasses," says Adams. Today, sweet feeds--also known as textured feeds--often contain pellets and other additives. A good sweet feed will have a low corn content with added oil/fat, giving the mix a low starch content and allowing you to provide sufficient energy without feeding a mountain of grain, says Adams. Reputable feed companies will also fix the feed's formula so your horse gets the same ration in every bag you buy.
"Most people think horses like sweet feeds better," he notes. "And they likely are the most palatable, especially for horses that are under stress, like performance horses."
The Pressure's On
Introduced to the equine scene in the 1980s, extrusion is the most recent processing technique to hit the horse market. As with pelleting, the extrusion process begins by grinding and mixing the grain. The resulting product is then conditioned using both steam and pressure, with temperatures reaching about 260ï¿½F. Because of the added pressure and higher temperatures, the extrusion process does a more thorough job of gelatinizing grains--breaking those starchy bonds--than micronizing, steaming, or pelleting, notes Adams.
Next, the conditioned mix is forced through an extruder--basically a steel tube with an auger that rotates the mix under increasing pressure. More steam and water are added, and the mixture is then shaped into nuggets using a die. The nuggets are exposed to cooler air, which makes them "pop" or expand. After drying, the final product contains less than 10% moisture.
Extruded feeds have met resistance in some circles and been hailed in others. Proponents note that extruded feeds have many of the same benefits as pellets--manufacturers can easily combine ingredients that horses can't sort out, the product has low dust levels, and its low moisture content makes for a long shelf life without the need for preservatives. In addition, the bulky nuggets can slow the horse's rate of eating, thus reducing the risk of colic and choke while helping satisfy the grazing urge.
Some studies have shown that, because of improved utilization of starches, extruded feeds also have greater overall digestibility than other feeds, including pellets. For instance, digestion of corn starch in the small intestine can be improved almost three times by extrusion. All of this means that the horse can extract more energy from less feed, which means you can feed less (based on weight) yet provide the same energy level as pellets or other feeds.
Critics of extruded feeds, however, argue that this is among the least palatable of horse feeds. The extrusion process also destroys some of the grains' natural vitamin content, so manufacturers must add excess amounts before extrusion in order to end with satisfactory levels. Extruded feeds also take up more space than other bagged feeds. And, like pellets, they are pricey and prevent you from examining the quality of individual ingredients.
Adams notes another potential pitfall to extruded feeds: It's possible that feeding high levels of a high-starch-containing diet could be a contributing factor in the incidence of developmental bone disease (i.e., osteochondritis dissecans) in growing horses. So if you're considering an extruded feed for a young horse, proceed with caution.
Add It Up
Unlike mechanical and heat processing, the tactic of adding non-grain ingredients to a feed doesn't alter grain's physical makeup. But it does aim to enhance the grain, particularly its nutritional value and palatability. While the list of potential additives is huge, here we highlight some of the most common, popular, and trendy ingredients.
Binding agents--Pellets need a binding agent to hold the ground grain particles together. In horse feed, molasses is probably the most common binder. Barley and wheat are other natural binding agents. Lignasol, an artificial binder, can be used.
Vitamins and minerals--While grains naturally contain some vitamins, levels are typically low and can fluctuate depending on the quality of the ingredient, explain Adams and Raub. In addition, they will naturally oxidize away. So feed manufacturers add high levels of stabilized forms of vitamins to help ensure optimum nutrition. Among the most common vitamins added to horse feeds are A (important for reproduction), E (a natural preservative/ antioxidant that helps ensure optimum function of the reproductive, muscular, circulatory, nervous, and immune systems), and H (a.k.a., biotin, helpful for improving hoof and hair quality and for the synthesis of fats, proteins, and glucose). Calcium, phosphorus, copper, zinc, and selenium are typical mineral additions.
Forage/fiber--As you know, horses need fiber. But these days, fiber doesn't just come from flakes of hay or grass pasture. Many feeds now include such highly digestible fiber sources as shredded beet pulp, soy hulls, or even alfalfa chaff. These help ensure that your horse receives adequate fiber and can also provide the calories (energy) usually lacking in high-fiber feeds. For instance, says Adams, shredded beet pulp provides as many calories as oats. In addition, he notes, "Soy hull- and beet pulp-based feeds are safer energy sources than grain because the majority of ingredients are digested in the hindgut, so you're not going to have that spike in glucose or insulin levels that causes hyperactivity."
Fat--Unlike grain starches, fat is easily digested in the horse's small intestine, yet delivers an energy punch at least equal to that of grain. According to Southern States, fat can supply 2.5 times more digestible energy than an equal weight of cereal grains. Thus, fat allows you to increase your horse's energy intake without increasing grain, and that minimizes the amount of starch for the digestive system to handle. Fat is also famous for adding shine to your horse's coat and is said to improve muscle performance. Vegetable oil--including soy, corn, and canola--is the most common fat used in horse feed. However, stabilized rice bran, flaxseed meal, and copra meal are also popular sources. While the average horse feed has just 2-3% fat, many high-performance feeds or special-needs (i.e., lactating mare) feeds have 6, 8, 10, or even 12% fat content.
Flavoring--Most horses gobble down grain with obvious delight. But for those finicky eaters in the herd, flavorings can help ensure optimum nutrient intake. Molasses is the most common flavor additive in the equine industry--particularly famous as the "sweet" in sweet feed. Research at Purina Mills continues to show that molasses does increase feed palatability. (If you're worried about the sugar content of molasses, relax. Laboratory research has shown that good hays and fresh pasture have higher sugar contents than molasses.)
Alfalfa meal is often used to increase the palatability of pellets, says Adams. One study, he adds, even showed that cherry was the most appealing flavor to horses, although no feed manufacturer seems ready to exploit this discovery quite yet.
Adams notes that flavorings can often be less important than what your horse is accustomed to: A horse might actually turn up his nose at a "better-tasting" feed simply because it's unfamiliar.
Other additives--Other equine feed additives include lysine, probiotics, and "natural health"-type products such as kelp meal and yucca. Lysine is an amino acid critical for growth as well as muscle and tissue development. Probiotics, which include yeast culture, and a variety of other products on the market help promote good digestion and overall intestinal health, particularly in relation to the health of microflora and digestive enzymes. Yucca, notes Adams, is an ammonia binder that reduces ammonia levels in blood and manure. Kelp meal is a source of micronutrients.
The bottom line on all additives, says Adams, is guarantees. "Anybody can say they have biotin or vitamin E," he explains. "You should look for feeds that guarantee a certain amount."
In addition, says Raub, make sure the additives are things that your horse actually needs. Otherwise, you could be wasting precious pennies on products that are not contributing any real nutritional value to your horse's diet. And you could be imbalancing his diet in other ways.
What Matters Most
When it comes to selecting the right feed for your horse, says Adams, Look for high-quality food that keeps your horse fit and happy--regardless of what's in it or how it looks.
After all, concludes Raub, "Even if you use all the processing methods that are available, a low-quality ingredient will still be a low-quality ingredient. You can't take wheat straw and process it into a great feed."
Briggs, K. Extruded Feeds. The Horse, June 2000, www.TheHorse.com/ViewArticle.aspx?id=139.
Briggs, K. Grains of Glory. The Horse, September 1997, www.TheHorse.com/ViewArticle.aspx?id=666.
Briggs, K. Pelleted Feeds: Packaged Nutrition. The Horse, October 1997, www.TheHorse.com/ViewArticle.aspx?id=635.
About the Author
Sushil Dulai Wenholz is a free-lance writer based in Lakewood, Colo. Her work appears in a number of leading equine publications, and she has earned awards from the American Horse Publications and the Western Fairs Association.
POLL: University Equine Hospitals