Horse owners often feed supplementary concentrates in addition to forage to provide additional calories or energy for performance. In a recent study, researchers at the Austrian University of Veterinary Medicine evaluated the effects of storage on corn (maize), oats, and barley, which are some of the main cereal grains in equine feeds.
Commercial Equine Grain Study Conditions
The researchers examined commercial cereals manufactured by different local companies and bagged for sale: a) native oat, barley, and corn; b) flaked oats; c) flaked barley; and d) flaked corn. They evaluated two bags of each, which came sealed and weighed 33-66 pounds. They opened one of the two bags immediately and stored it for 42 days at a horse farm. The unopened control bag remained in the same storage area for 42 days for later testing. The bags were stored upright on a wooden pallet on a concrete floor in a dark room with no air draft. Storage temperature over the 42 days ranged from 63-70 degrees Fahrenheit with 58-74% humidity.
The researchers took 2-liter samples from the top and bottom of each bag for examination. They assessed each cereal for texture, odor, taste, structure, color, cross-section, and visible contaminants. They compared color changes associated with mold, unripeness, seed treatment, and dust to a typical, expected color. They also assessed particle size and analyzed cereal from the top of each bag for mycotoxins.
Study Results
Here are some interesting results from the 36 samples:
- Impurities were found in 28 samples and included rye, wheat, wild oats, chaff, husk, sand, earth, and manure.
- Eight samples, mostly corn, were impurity-free.
- Oats had higher impurities than barley or corn.
- Unopened samples had higher impurities than the opened samples stored for 42 days.
- Processing increased numbers of flawed corn components.
- All barley samples had pest components, such as moth larvae, meal mites, and booklice.
- Control samples contained flawed grains and pests, with corn having the fewest impurities.
- Storage conditions did not affect sensory scores, and all were considered acceptable.
- Color changes occurred in openly stored bags of oats and barley with blue-gray discoloration of native oats.
- Grains from the top and bottom of the bag had the same chemical compositions.
- Particle size was similar between the top and bottom of the bag. Processing increased particle size.
- All samples had concentrates of secondary metabolites of fungi.
- Fumonisin was only found in corn.
- No sample had ergot alkaloids, which are mostly associated with rye cereals.
- Barley had the most concentrations of pesticides, including piperonylbutoxide, but at low levels.
- All samples retained dry matter content above 88%. Levels below 85% are considered unacceptable.
The researchers said they were surprised to see commercial grains containing “considerable amounts of impurities, flawed grains, and pest components.” Storage at stable conditions over 42 days did not increase the contaminants or change the cereals’ nutrient composition, even in open bags. The storage conditions in this study (63-70 degrees Fahrenheit with less than 75% relative humidity) were within the safe range for cereal grains.
Significance for Equine Grains
The study author said these findings indicate that “oats are prone to botanical impurities and earthy components; maize is physically damaged from processing; and barley is prone to pest contamination, especially after processing.” The mechanical cracking of grains enables invasion by pests. Because impurities, contaminants, and pests were present in the unopened bags, it appears they “originate from the field as well as in the manufacturing facility.” In the EU, feed materials are required to have a minimum of 95% botanical purity; these samples did not violate that standard.
The presence of pests, however, is concerning because they have the ability to multiply in warm and moist conditions. Dust, debris, and microorganisms are known for having adverse effects on the equine respiratory tract. Odor and physical appearance of feed spoils when certain levels of microbes are triggered by high humidity, high temperature, and physical damage. Mycotoxins are of great hazard to equine health, especially those found in moldy corn from Fusarium. Only found in grain, fumonisin was detected at still-safe levels, as were aflatoxins, zearalenone, deoxynivalenol, and ergovaline.
Final Thoughts
The authors recommend microscopic evaluation of cereal grains and their products as well as maintaining temperature and humidity within safe storage levels. Because feeding a single grain source can “lead to a high intake of certain impurities and contaminants,” it might be beneficial to feed a combination of grain types. Horse owners should examine cereal grains upon opening the bag. While this study occurred in the EU, it highlights the value of examining cereal grains fed to horses around the world.
Reference
Khiaosa-ard R, Czermak S, Hollmann M, et al. Changes in nutritional and hygienic quality due to storage of native and processed grain cereals intended for horse feeding. Journal of Stored Products 2024; doi.org/10.1016/j.jspr.2024.102310
Related Reading
- Beet Pulp Supplements for Equine Gut Health
- Potential Harm to Horses from Probiotics
- Diet Effects on the Equine Microbiome
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