Photo cutline at bottom. Click here for high-res image.
GAINESVILLE, Fla. — Corn silage is an important dairy feed but it sometimes harbors an unwelcome addition – Southern corn rust, a fungal disease that thrives under hot, humid conditions.
The fungus responsible, Puccinia polysora, seems harmless to cattle. However, a Southern corn rust infection can severely reduce the yield and nutritional value of corn plants and inhibit their fermentation to silage.
Worse, it damages corn tissue, providing a gateway for opportunistic microbes such as Aspergillis. This genus of fungi includes species that produce a toxic compound called aflatoxin, which can harm or even kill cattle that eat contaminated silage. Aflatoxin can also be transmitted to the milk of cows that eat contaminated foods; in people aflatoxin can cause cancer, other diseases and death.
Now, researchers with the University of Florida’s Institute of Food and Agricultural Sciences have found a way to control negative effects of Southern corn rust on silage and prevent aflatoxin accumulation, by inoculating the silage with beneficial bacteria.
The study was published in the September issue of Journal of Dairy Science.
“We believe this is the first study to examine the potential of bacteria to reduce the negative effects of Southern corn rust on the safety, nutritive value and fermentation of corn silage,” said Adegbola Adesogan, a UF/IFAS animal sciences professor specializing in ruminant nutrition.
The bacteria used in the study were Lactobacillus buchneri and Pediococcus pentosaceus, though the alfatoxin inhibition was likely due to L. buchneri. Both bacteria are commercially available and commonly added to silage to promote fermentation and increase shelf life, respectively.
In the study, rust-infected chopped corn was inoculated with the bacteria and compared with untreated rust-infected corn after about three months of ensiling. The bacteria prevented accumulation of aflatoxin; it also reduced spoilage and adverse effects of rust on the fermentation and nutritional value of the silage.
Next, the researchers hope to discover more about ways to use bacteria to enhance the quality of ensiled feeds.
“We’re looking at strategies to improve the safety, nutritional value and preservation of ensiled feeds with inoculants and other additives,” he said.
The team included Adesogan, Sam Kim and Oscar Queiroz, all with UF’s animal sciences department.
Writer: Tom Nordlie, 352-273-3567, firstname.lastname@example.org
Source: Adegbola Adesogan, 352-392-7527, email@example.com
Adegbola Adesogan, an animal sciences professor with the University of Florida’s Institute of Food and Agricultural Sciences, is one of the authors of a new paper showing that beneficial bacteria can reduce the negative impacts of Southern corn rust on silage, and prevent build-up of the toxic chemical aflatoxin. Corn silage is one of the most important feeds for dairy cows. The study appears in the September 2012 issue of Journal of Dairy Science.