When your horse is just not himself, insidious toxins may be to blame. Your horse may be losing weight, exhibiting feed withdrawal symptoms, or having sudden bouts of hyper-excitability, all of which your veterinarian has checked and rechecked, but to no avail. While such changes in behaviors point to any number of disorders, have you considered mycotoxin overload, or mycotoxicosis?
Mycotoxins are a by-product of mold found in concentrates and forages, and as the name suggests, create a toxic environment when consumed. Dr. Swamy Haladi, global technical manager for the Alltech Mycotoxin Management Team, says that although harm is not necessarily credited to mycotoxins directly, it is thought they can cause immune suppression, thereby weakening the host in the process.
“Toxins are first formed in the field with levels fluctuating in response to weather conditions during the growing season,” Haladi explains. Molds are able to propagate under sub-optimal storage conditions as well, leading to more mycotoxin production.
“The result is that mycotoxin overload can leave a wake of clinical signs affecting the liver, as well as gastrointestinal, neurological and reproductive systems,” Haladi says. Cases of death have also been attributed to this.
Mycotoxicosis tends to build up over time. “It’s the protracted feeding of contaminated ingredients that increases the risk of toxicity,” Haladi says.
Mycotoxin exposure can be traced to six major groups of toxins that typically attach to corn, wheat, barley, oats, rye, soybean meal, alfalfa, and forages such as hay.
“Under the right conditions mycotoxins can interact with each other to become even more toxic,” Haladi says.
One example is aflatoxins, predominately found in corn, soybean meal and alfalfa, and a possible cause of weight loss, fever, hemorrhage, incoordination, and yellowing of the eyes or skin. But, Haladi says, it is the combination of Fusarium toxins, with a spotlight on the sub-class fumonisins that are a major threat to horses. “Fumonisins are linked primarily to corn and corn by-products and target the nervous system, accounting for debilitating and often permanent neurological damage, coined ‘blind staggers’ or ‘moldy corn syndrome’,” Haladi says.
The challenge in diagnosing mycotoxicosis is that many symptoms mirror other conditions, and without established testing procedures, positive identification is often overshadowed by more easily recognized disorders.
To rule out the possibility, Haladi suggests sending feed or forage samples to an accredited laboratory to assess mycotoxin levels, and to analyze as many toxins as possible to account for mycotoxin interactions.
Once detected, mycotoxicosis is difficult to treat. Resistant to decomposition or being broken down during digestion, mycotoxins are equally resistant to extreme temperature applications.
Although no industry-wide mandate exists, the U.S. Food and Drug Administration and the Association of American Feed Control Officials (AAFCO) have made an attempt to control the problem with recommended fumonisin levels not to exceed five parts per million, and corn not to exceed 20 percent of the non-forage portion of the diet. Many companies are taking their own steps to monitor the situation by actively overseeing the quality of their nutrient sources or choosing not to feed contaminated feed.
Another option is to use an effective mycotoxin adsorbent, either silica-based polymers or carbon-based organic polymers. Silica-type materials, such as clays, are readily available and many have shown to be effective against aflatoxins, but ineffective against other types. Haladi recommends an organic mycotoxin sequestering agent that can be used at practical levels of inclusion for all species of mycotoxins.
WHAT YOU CAN DO
Even with all the preventive measures employed at different stages of production, maintaining low mycotoxin levels still requires due diligence and good management.
While many feed companies are taking steps to ensure quality control, not all are on the bandwagon. Without set industry standards, they are at liberty to include ingredients based on cost rather than quality; it falls to the horse owner to be proactive and learn how to tell the difference between those that provide high-grade products and those that do not.
The first line of defense is to read the feed tag. “The feed tag guarantees the nutrient values that ultimately end up in your horse’s digestive system and bloodstream,” says Nick Adams, Alltech’s Mycotoxin Management Team Global Sales Director. Adams cautions that even though the nutritional analysis must conform to AAFCO rules, there is more than a little wiggle room when it comes to changing, modifying or substituting actual ingredients.
In fact, AAFCO offers manufacturers a choice of formulation methods under the banner of “collective terms” and “descriptive terms.” AAFCO states that it is acceptable to list ingredients in groupings, whereby the manufacturer may interchange them based on what is either available or least expensive as long as they maintain the same nutrient guarantees found on the tag. Adams illustrates the point with the term, roughage products, which he says can include soybean hulls and beet pulp, nutritious spin-offs of the milling process, but can also include and/or be substituted with peanut hulls, which are generally used as cheap fillers, lacking in nutrients, and worse, prone to containing high levels of mycotoxins.
Descriptive terms, on the other hand, spell out each ingredient so that what is recorded on the tag is actually in the bag. He further recommends that horse owners look to companies that have fixed formulas and list their ingredients in order of nutritional importance.
“By listing ingredients in descending order of inclusion, the premium nutrients will be featured on top, and while these feeds tend to be more costly, it speaks to the value the manufacturer places on providing quality nutrition, and consequently, is more likely to implement mycotoxin controls as well,” Adams says.
Adams adds that reputable manufacturers tend to have established protocols for reviewing and approving suppliers who provide only high-grade ingredients.
Along with diligently reading feed tags, horse owners should test their hay at harvest time or if they notice moldy or dusty bales, as mycotoxins are often present in forage. University extension services offer hay analyses.
TAKE HOME MESSAGE
Adams sums it up by urging horse owners to take an active role in their horses’ nutritional welfare from the ground up.
“Have your hay analyzed regularly, and contact your feed company to discuss their mycotoxin control practices. By discovering how they deal with the issue, you can make an informed decision as to whether the feed measures up to your standards,” Adams says.
Finally, Adams recommends contacting your veterinarian with questions, especially if your horse is exhibiting signs that could be related to mycotoxicosis.
Tips to Manage Potential Mycotoxins
Dr. Hawkins gives these five tips for producers dealing with feedstuffs compromised by 2012’s drought:
1. Dry corn to 15 percent moisture or less within 24-48 hours of harvest. Reducing the moisture will help to stabilize the mold level and prevent further growth.
2. Screen grain to remove fines, broken kernels and foreign material as these are precursors to increased mold growth.
3. Have all ingredients that are grain or are sourced from grain analyzed for mycotoxins. With more than 500 known mycotoxins, the greatest percentage of samples contain from two to five mycotoxins.
4. Mycotoxin analysis should be conducted regularly throughout the storage process, as temperature and moisture changes will affect mold growth.
5. When purchasing ingredients, producers may find ingredients from certain areas that are consistently higher in mycotoxins. Know the levels of mycotoxins that are practical and can be fed and the guideline limit that should not be fed to livestock.
Dr. Max F. Hawkins has over 40 years of livestock experience, encompassing production, university teaching and nutrition companies. He is currently with Alltech ( www.alltech.com ), working with the North American Mycotoxin Management Group.