Providing supplemental feed or hunting whitetail deer over feeders filled with “deer corn” has become common practice for most Texas hunters and wildlife managers. While this is perfectly legal and often beneficial for wildlife, managers and hunters need better information on the harmful effects of aflatoxin as they could be affecting not only the health of their whitetail deer but also all other wildlife that is exposed to the feed.
Aflatoxin is a fungus produced by corn and other cereal grains typically during droughty years or when the plants become stressed. Aflatoxin can be prevalent when grain is harvested, but contaminated feed can continue to increase in aflatoxin level when stored under warm moist conditions. Feed that is not contaminated can become so simply by being stored or fed through feeders that have previously held grain that had high levels of aflatoxin. For feed to be labeled as “Wildlife Feed” or “Wildlife Safe”, State regulations require that it contain less than 50 parts per billion aflatoxin. The only problem is that many times feed containing less than 50 ppb aflatoxin at the time of purchase, will contain higher levels when it is made available to wildlife as toxin levels can increase until it is actually consumed. Texas Feed and Fertilizer recommends that grain tested higher than 100 ppb not be used to feed free ranging deer, but little information is available on how aflatoxin can affect our whitetail deer. Fawns are the most susceptible to aflatoxin poisoning, while other economically important species such as wild turkey, dove, quail and songbirds have been found to be even more sensitive to high aflatoxin levels.
Studies have shown that high aflatoxin levels will cause liver damage, blood clotting abnormalities, cancer, immune dysfunction and death. The major underlying problem with this toxin is that it ultimately makes animals vulnerable to secondary infection from other disease due to a depleted immune system. While it may not be the main cause of death, a depleted immune system will make animals more sensitive to diseases they should have a natural resistance to. Respiratory diseases and bluetongue are often encountered by whitetail deer in our area. Deer that have a healthy immune system have a much better chance of overcoming these versus those that have a weak immune system. These responses could also make these animals more susceptible to predation by natural predators such as coyotes or birds of prey, ultimately causing negative effects on the total population. The FDA has established that aflatoxin levels in grain that is consumed by humans, dairy cattle and young livestock not be above 20ppb, while grain that tests higher is often diverted to other uses such as wildlife feed. Grain that is tested at below 20 ppb will therefore sell at premium to grains that only test below 50 ppb.
If corn is made available for wildlife, it is important to obtain it from a reputable company that tests all grain purchased for aflatoxin levels and maintains strict quality control methods for storage. Short of freezing, there are few storage methods that can completely prevent the growth of aflatoxin if present in high levels. There are a few companies that will only purchase human grade feed grain which will contain less than 20 ppb when it is received at their facility, but the industry standard for most companies is at 50ppb for wildlife feed. If feed is sold for wildlife feed or “deer corn”, the level of aflatoxin it was tested for should be on the bag or feed tag. If no level is shown, it is strongly recommended that you contact your supplier or switch to another company that maintains what level of aflatoxin they will tolerate in grain that is purchased. Most biologists and researchers feel that the feed industry should hold the same standard for wildlife feed as they do for human and domestic livestock use. This would maintain that they only purchase grain that tests below 20ppb to package and sell for wildlife feed, at least until further research can be done to show how aflatoxin can ultimately affect our wildlife populations.