We’re all familiar with roasted coffee beans, peanuts and sunflower seeds, and we all know that roasting greatly increases the flavor of these foods. If you pay attention to ingredients lists on your horse’s feed bag, you probably notice roasted soybeans as well. Roasting or toasting is done for a variety of reasons beyond its flavor-enhancing effect, however, and all grains can be roasted. One of the reasons interest in roasted grains for horses is on the rise at the moment is its ability to greatly reduce mold and mycotoxin contamination of grains.
What Roasting Can Do
Roasting, like other processing forms that use heat, has its pros and cons (see chart). The improved starch digestibility of grains like corn, milo and sorghum means you can feed less for same number of calories. Basically, you’re getting more nutrients per pound, of the ones that survive the processing. This is clearly a good thing. However, one study showed higher glucose and insulin responses in horses fed roasted grains vs. untreated grains, and that is not a good thing, especially in horses that may be on the verge of becoming insulin-resistant. The heat process may also destroy some of the nutrients (see chart), but this can easily be counteracted by careful supplementation of the grain, such as extra thiamine and essential amino acid supplementation.
If you check any website that sells roasted grains for horses, you’ll see that they are said to lessen the chance of ulcer formation, improve soundness, fertility, improved flavor, less acidosis (associated with laminitis) and more. Clearly, though, the greatest appeal in light of the recent aflatoxin contaminated grain fiasco is in mold and mycotoxin control. However, while roasting will kill molds and harmful bacteria, it is not 100% successful in eliminating mycotoxins (see sidebar from FDA on acceptable levels of contaminants).
In one sense, mycotoxins are a fact of life. The fungi that produce them live in the soil and are ready and waiting to take advantage of grain conditions that allow them to take hold. Drought stresses grains and causes cracks where fungi can proliferate on the rich nutrients inside the grain. Some molds flourish more superficially on the grains and do best under high humidity conditions. Worst of all is a midsummer drought followed by high heat and humidity.
Roasting isn’t the only way to reduce mycotoxins in feeds. An article in the February 2005 Food Additives and Contaminants found ”extrusion cooking generally decreases the mycotoxins levels at rates depending on different factors such as the type of extruder, the type of screw, the die configuration, the initial mycotoxin concentration, the barrel temperature, the screw speed, the moisture content of the raw material and the use of additives. Reductions of 100, 95 and 83% for fumonisins, aflatoxins and zearalenone, respectively, have been reported during extrusion cooking of cereals, while lower reductions were observed for deoxynivalenol, ochratoxin A and moniliformin, where maximum reductions did not exceed 55, 40 and 30%, respectively.”
The FAO is the Food and Agriculture Organization of the United Nations. It is similar to a combination between our USDA and the foods division of the FDA.
In their most recent publication on mycotoxins, written by two researchers from the Toxicology and Mycotoxin Research Unit of the USDA, they talk about screening grains, seeds and nuts, how to minimize growth during storage and took a look at decontamination methods. The bottom line was that thermal treatment of infested grains isn’t 100% effective and avoidance of mycotoxin problems still has to rely heavily on diverting those grains out of the food supply for people and highly susceptible animals like the horse.
The interest in feeding roasted grain is an understandable way to go in horse feeding, as it does reduce the risk of feeding contaminated grain. However, it’s not the same as feeding a traditional, untreated grain.
It’s also likely to be more expensive, because you’re paying for an additional manufacturing process. In addition, there’s currently a limited geographic distribution area, which is a downside to anyone not living within a reasonable distance from a distributor. You may also have to pay for added vitamins that you didn’t need to buy previously.
Finally, with a rapidly growing increase in the number of diagnosed cases of insulin-resistant horses, we worry about the study showing a rapid, higher glucose and insulin response when comparing horses fed roasted grains vs. those fed untreated grains.
We consider roasted feeds a growing sector of the industry to watch. It’s heading in the right direction, but we’re not ready to make a total switch. Clearly, more study is needed.
For more information on the feed recall, see our July 2008 issue, which is available at www.horse-journal.com or by calling 800-424-7887. Other related articles include: ”Legal, But Deceptive Feed Labels” (April 2006), ”Safety In Equine Feeds” (July 2007), ”If He Won’t Eat It, Check Feed Quality” (February 2007), ”Hays And Molds” (July 2007).
We have an article in the works on the best horse feeds in North American, and we would appreciate your input. Send a list of your current feed manufacturers to us at the editorial office (page 2) or via email to [email protected]
Article by Horse Journal Veterinary Editor Eleanor Kellon, VMD.