Elevated DON risks a problem for pig farms

Thanks to a period of wet and snowy weather parts of the U.S. and Canada, experts are advising operations that handle corn or feed ingredients to be cautious of mycotoxins going forward.

Of particular concern is deoxynivalenol, or DON. This mycotoxin is produced by a mold that flourishes in wet conditions and is a major health threat if consumed in animal feed. Pigs show an especially high sensitivity to DON — contamination in swine feed can lead to reduced growth, less nutrient intake from vomiting, a weakened immune system and reduced litter size.

Farms.com reports that 25% of samples tested by the Ontario Ministry of Agriculture, Food and Rural Affairs had DON levels greater than 5 parts per million (ppm), and 15% tested between 2 and 5 ppm. The Canadian Food Inspection Agency recommends that DON shouldn’t exceed 1 ppm in mixed feeds. These high numbers mean that contaminated loads are being rejected by elevators.

The Ontario Animal Health Network suggests the following for managing DON in swine feed:

• Clean and dry grain ASAP

• If contaminated grain is unavoidable, try to keep it away from breeding swine and recently weaned pigs

• Ask if testing has been performed when buying dried distillers grains with solubles (DDGS)

• Reduce mycotoxin concentration by blending contaminated and non-contaminated grain

• Increase nutrient density of the pigs’ diet to combat reduced feed intake caused by DON

DON in pigs

DON is also known as vomitoxin for a reason — it induces vomiting in pigs, so much so that they will reduce their own feed intake. In pigs, it causes nausea, gastroenteritis, diarrhea, immune suppression and can lead to blood disorders.

When pigs ingest DON-contaminated feed, their intestinal epithelial cells are targeted. These cells are located in the stomach, right near the small intestine. The toxin is absorbed into the system there.

The pig’s gut is an important barrier to toxins; DON can enter regardless of the intestines’ backups. Barriers include tight junctions that essentially seal the intercellular space. DON can not only cross through these junctions, but also increase the permeability of the intestine while doing so. Thus, pigs that may be chronically exposed to DON-contaminated products have a higher DON uptake.

But this isn’t the end of the path of DON. Any absorbed mycotoxins can re-enter the intestine through the same initial path (the intestinal epithelium) or through enterohepatic circulation, a fancy way of saying vomiting. If a pig were to re-ingest the bile, the DON would again be re-absorbed. Either of these scenarios increases the exposure along the gastrointestinal tract.

See our website for more information on the products and services Neogen offers for the care of swine, or for the detection of DON and other mycotoxins in feed.