Mycotoxins and silage
October 3, 2012
What a strange summer. After a dry winter and spring we went into drought. The small grain was OK, but the row crops were severely affected. About half the corn in our area has been cut for silage, but some fields have some ears and may yield 30-40 bushel per acre. Now we are told the corn may be extremely high in mycotoxins.
All feeds contain fungal spores. If temperature and humidity are just right, the spores sprout and grow creating mold. Most molds are non-toxic but some produce a toxin (mycotoxin) which interferes with gains, animal health, and overall productivity.
Mycotoxins are harmful toxins produced by molds as a byproduct of normal growth. Different molds cause various health problems for animals. These mycotoxins can be typed and measured at diagnostic labs. We send our samples to North Dakota for their individual mold screen. Limits have been set for individual toxins in purchased grains, but mycotoxins effects are synergistic in nature. This means if you have more than one type of mycotoxin the effects will be additive, worse than single toxins.
We know mycotoxins can be produced in storage, as well as in the field. Silage is an excellent substrate for the growth of mold and therefore mycotoxins. The energy of the silage is needed for mold growth. Generally well packed and sealed silage piles have less oxygen available for mold growth.
When I went to school we believed that cattle (the rumen) degraded mycotoxins. Any and all feeds tested high in mycotoxins were blended and fed to our feed lot cattle. Now we know specific mycotoxins can cause lameness and abortion shortly after consumption. Other mycotoxins, when fed in low levels over a long period of time, can cause slower growth rates, inconsistent manure (diarrhea) and poor conception rates. Several years ago we had a dairy producer with excessive mycotoxins in their milk. Rations were changed after mold was found in stored corn and the problem disappeared.
This year in our area the silage was cut while it still had high moisture content (75 – 85 percent). This usually results in a pile which doesn't pack very well and drains water all fall and winter. The sugars are still present in the stalk and the poor packing allows more oxygen to enter the pile. This results in excessive mold growth and the chance of subsequence problems. Late winter is when we normally see sporadic abortions in our herds being fed large amounts of silage. The pile has usually been open for awhile and we begin to see mold growth on the edges of the pile. With the high hay prices most producers will not have much dry forage to feed to their animals. This will greatly increase the chance of problems in your herd.
Mold spores are everywhere. Grains and purchased feedstuffs are always a possible source. Silage causes problems in our area every year. This year, with the low quality and increased moisture, our problems may be higher than normal. Consult with your veterinarian or feed nutritionalist to decide if you need to test your feedstuffs for mycotoxins. If you observe abortions and infertility, or suspect poor weigh gains and decreased productivity; test your feeds. Don't let these in apparent silent mycotoxins steal your profits.