Keep track of moldy corn issues this fall
Published: Nov 12, 2009 12:00 am - 0
By Russ Daly
Special to the Farm Forum
Dry weather - thankfully - has returned to the region, allowing some “catch-up” for the soybean and corn harvests. The cool wet weather we had through October has had important implications for the corn crop. Conditions have been favorable for mold formation on corn ears, and in some cases, stalks, leaves, and husks as well. Early indications are that a great percentage of the corn crop has been affected-not just in South Dakota, but across the Corn Belt. The presence of these molds has raised many questions about the fitness of this corn: both for marketing purposes and for use as livestock feed.
SDSU's Plant Pathology and Olson Biochemistry Labs, along with many other private and university labs, have been busy fielding calls and testing corn affected with these molds. So far, many of the molds observed have not been ones that produce mycotoxins; but these are early results and more will be known as the harvest progresses.
Understanding the difference between molds and mycotoxins is important. Just because an ear of corn has mold does not necessarily mean it will be harmful to animals. A lot of the molds we people encounter on spoiled foods won't hurt us either, but it doesn't mean the food is going to taste good. Likewise, it's possible that even some of these harmless molds will create off-flavors and decreased feed consumption as a result.
Certain molds, however, under just the right conditions, produce chemicals as a by-product of their growth called mycotoxins. These chemicals have various effects on animals and sometimes on people.
One of the types of mold for which conditions have been right is fusarium mold. This is a white to pink cottony-appearing mold that has potential to produce the mycotoxin called fumonisin. The animal most sensitive to fumonisin is the horse. Relatively small amounts of fumonisin eaten by a horse can result in what has been known for years as “moldy corn poisoning.” The toxin has its effect on the white matter in the brain, causing death of brain cells. Clinical signs consist of behavior change, weakness, staggering, an inability to rise, and eventually, death. There is no treatment or vaccine. Especially worrisome is the possibility that corn stalks or leaves may be affected with the fungus, thus potentially the toxin. This leads me to caution horse owners to at the very least be extremely cautious letting horses run on cornstalks this fall, or even exposing them to corn stalk bedding. Fumonisin can also affect cattle and pigs, but at much higher concentrations than affect horses.
Gibberela mold, a pinkish mold that develops from the tip of the ear inward, has the potential to create vomitoxin, which when given to pigs in sufficient quantity, has exactly the effect that its name implies! More importantly, at lower levels, it causes feed refusal, resulting in decreased weight gain and efficiency. Gibberela mold also may possibly produce zearalenone, which is a mycotoxin that has reproductive effects, especially in pigs, causing premature estrus cycles, vulvar swelling, and prolapses in growing gilts. At higher concentrations it can affect reproduction in heifers and cows.
There are some other potential mycotoxins to look out for, but they do not seem to be as common this season. The most notable of these is aflatoxin, a potent cancer-causing agent that suppresses the immune system and causes liver damage in pigs and cattle. Aflatoxin generally is produced by molds during hot weather, so its presence is not really expected this fall.
The bottom line with mold issues in corn to be fed this year is that it is much easier to test the grain or feed now, or before feeding, to get an idea of whether mycotoxins are present and if so, in what quantity. Clinical signs due to mycotoxins tend to be very vague and may not show up until long after the offending feed is fed, making diagnosis after the fact difficult.
The good news is that there are many resources to help livestock producers sort out potential mycotoxin issues this fall. SDSU's Cooperative Extension Service has a very useful website, http://sdces.sdstate.edu/weatherDamagedGrain/index.cfm, and local Extension educators and veterinarians are great resources as well.
Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University. He can be reached via e-mail at russell.daly@sdstate.edu or at 605-688-5171.
Special to the Farm Forum
Dry weather - thankfully - has returned to the region, allowing some “catch-up” for the soybean and corn harvests. The cool wet weather we had through October has had important implications for the corn crop. Conditions have been favorable for mold formation on corn ears, and in some cases, stalks, leaves, and husks as well. Early indications are that a great percentage of the corn crop has been affected-not just in South Dakota, but across the Corn Belt. The presence of these molds has raised many questions about the fitness of this corn: both for marketing purposes and for use as livestock feed.
SDSU's Plant Pathology and Olson Biochemistry Labs, along with many other private and university labs, have been busy fielding calls and testing corn affected with these molds. So far, many of the molds observed have not been ones that produce mycotoxins; but these are early results and more will be known as the harvest progresses.
Understanding the difference between molds and mycotoxins is important. Just because an ear of corn has mold does not necessarily mean it will be harmful to animals. A lot of the molds we people encounter on spoiled foods won't hurt us either, but it doesn't mean the food is going to taste good. Likewise, it's possible that even some of these harmless molds will create off-flavors and decreased feed consumption as a result.
Certain molds, however, under just the right conditions, produce chemicals as a by-product of their growth called mycotoxins. These chemicals have various effects on animals and sometimes on people.
One of the types of mold for which conditions have been right is fusarium mold. This is a white to pink cottony-appearing mold that has potential to produce the mycotoxin called fumonisin. The animal most sensitive to fumonisin is the horse. Relatively small amounts of fumonisin eaten by a horse can result in what has been known for years as “moldy corn poisoning.” The toxin has its effect on the white matter in the brain, causing death of brain cells. Clinical signs consist of behavior change, weakness, staggering, an inability to rise, and eventually, death. There is no treatment or vaccine. Especially worrisome is the possibility that corn stalks or leaves may be affected with the fungus, thus potentially the toxin. This leads me to caution horse owners to at the very least be extremely cautious letting horses run on cornstalks this fall, or even exposing them to corn stalk bedding. Fumonisin can also affect cattle and pigs, but at much higher concentrations than affect horses.
Gibberela mold, a pinkish mold that develops from the tip of the ear inward, has the potential to create vomitoxin, which when given to pigs in sufficient quantity, has exactly the effect that its name implies! More importantly, at lower levels, it causes feed refusal, resulting in decreased weight gain and efficiency. Gibberela mold also may possibly produce zearalenone, which is a mycotoxin that has reproductive effects, especially in pigs, causing premature estrus cycles, vulvar swelling, and prolapses in growing gilts. At higher concentrations it can affect reproduction in heifers and cows.
There are some other potential mycotoxins to look out for, but they do not seem to be as common this season. The most notable of these is aflatoxin, a potent cancer-causing agent that suppresses the immune system and causes liver damage in pigs and cattle. Aflatoxin generally is produced by molds during hot weather, so its presence is not really expected this fall.
The bottom line with mold issues in corn to be fed this year is that it is much easier to test the grain or feed now, or before feeding, to get an idea of whether mycotoxins are present and if so, in what quantity. Clinical signs due to mycotoxins tend to be very vague and may not show up until long after the offending feed is fed, making diagnosis after the fact difficult.
The good news is that there are many resources to help livestock producers sort out potential mycotoxin issues this fall. SDSU's Cooperative Extension Service has a very useful website, http://sdces.sdstate.edu/weatherDamagedGrain/index.cfm, and local Extension educators and veterinarians are great resources as well.
Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University. He can be reached via e-mail at russell.daly@sdstate.edu or at 605-688-5171.
Bookmark/Search this post with:
Delicious
Digg
StumbleUpon
Reddit
Facebook
Technorati