Sunday, January 22, 2012

Mycotoxins: Feed Hazard

Mycotoxins--toxic substances secreted by mold--are the latest food safety concern hitting the news this month in China. Last month, aflatoxin was discovered in milk products manufactured (but not sold) by one of China's largest dairy companies. Earlier this month aflatoxin was found in peanut oil recalled by authorities in Guangdong Province. These incidents are just the tip of the iceberg of a much broader problem with mycotoxins in China. The discovery of aflatoxin in consumer products and the adjective "cancer-causing" got peoples' attention even though no one was actually harmed.

Mycotoxins in moldy grain are a much broader problem that sometimes kills livestock but more often makes them less productive and less resistant to disease. Mycotoxins have been a major concern for the animal feed and livestock industries in China for some time.

In 2009, feed millers in Guangdong Province attended a meeting to hear about a Shanghai company's mycotoxin detection equipment. The article on the meeting said that 100% of corn has mycotoxins in it and at least 90% of compound feed contains them. At the meeting it was reported that feed mills had to compensate farmers for 10 million ducks that died from aspergillus in feed. During a period of high hog prices in 2004, mycotoxin poisoning caused many sows to abort or deliver dead pigs. During 2006-07 there was widespread swine fever (and a big spike in hog prices) that some experts in China link to mycotoxin poisoning. Testing cited by the article said contamination was especially higher in brewers' grains (DDGS) which concentrate the toxins in the residue left after distilling alcohol from corn.

A 2010 article from veterinarians at Sichuan Agricultural University, "Fully Recognize The Danger of Feed Mycotoxins," describes mycotoxins as a worldwide public safety issue. The Sichuan scientists say there is mycotoxin contamination at every stage of the food chain from farm to table and its seriousness should attract our full attention. The Sichuan veterinarians say there are multiple kinds of mycotoxins, and where you find one there are probably others present. They report that FAO says 25% of grain worldwide is contaminated, and samples from China find contamination as high as 70%-100%. There are different contaminants for various feed ingredients, seasons, and kinds of feed.

Toxins cause diarrhea, vomiting, or stomach pain that can lead to coma or death, but they more commonly cause subacute symptoms that reduce animals' productivity and resistance to disease. Results include: decreased feed intake, diarrhea, slow weight gain, lower egg or milk output, reduced breeding ability and lower feed utilization. The Sichuan veterinarians say research shows that low degrees of contamination can reduce feed utilization by 10%-20%. They say this could mean a waste of 10 mmt of feed in China. Another hazard of sub-acute mycotoxin is breakdown of the immune system, weaker resistance to stress and pathogens, and in some cases vaccines are made less effective. The veterinarians suggest that research should be conducted on whether the widespread disease problems and high use of antibiotics are linked to mycotoxins in feed.

A December 2011 article reported that research in southern provinces found 89% of feed was contaminated with mycotoxins. The article attributed high levels of mycotoxins to flooding and inadequate drying of grain that led to mildewing. This article says that mildew can reduce the nutritional value of feed by using the vitamins B and E in grain and reducing amino acids. Mildew can also alter the smell and taste of feed, making it less palatable to hogs.

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