As corn harvest winds down, farmers need to watch for potential molds and fungus in corn. Fields that were hit with late-summer hail could pose a particular risk. Also drought-stressed corn is susceptible to aflatoxin-- a toxic metabolite produced by the ear-rotting fungus Aspergillus flavus.
With the high levels of distillers dried grains with soluble fed to swine today, mycotoxin monitoring should always be on producers’ checklist. During the ethanol production process, mycotoxins become concentrated in DDGS to the tune of three to four times the level in the original corn source. With growing interest in alternative feedstuffs, it’s worth noting that wheat-mids can carry high mycotoxin levels as well.
With harvest 65 percent complete, delays haven’t been a concern, but the risk of molds and toxins worsen as the crop remains in the field.
Kansas State University Extension swine specialists Mike Tokach and Joel DeRouchey offer the following advice regarding mycotoxin issues and swine.
•If possible, clean the grain before storage. Removing damaged kernels lowers toxin levels (by about 50 percent).
•Store at less than 15 percent moisture (13 percent or less is ideal) to limit further fungal growth and toxin production.
•Flush to clean the system after handling contaminated corn (put flush in a contaminated bin).
•Consider adding propionic acid to corn before it goes into storage if fungus is present and a possible concern. 0.5 percent addition of propionic acid limits further fungal growth.
•Monitor grain bin temperatures as hot spots will increase fungal growth and toxin production.
•Segregate corn into high- and low-mycotoxin-level bins if possible. Corn with less than 20 parts per billion can be fed in sow, nursery and late finisher diets. Corn with greater than 20 ppb can be fed to finishing pigs.
•Use low-test-weight corn quickly. It does not store well.
•Monitor dried distillers grains with soluble supplies as Aflatoxin may be four times higher in DDGS than in the corn used to make it
“Keep in mind that aflatoxin is a carcinogen, and that levels build up in the body over time,” Tokach says. “So, when feeding corn that contains aflatoxin, there may be reduced feed intake in the short term, but it’s the long-term where the biggest negative impact can occur.” When feeding to grow/finish pigs, there’s often no adverse effect if corn contains less than 200 ppb aflatoxin, but at 200 to 400 ppb reduced growth can occur and immune systems can be compromised, he notes. At 400 to 800 ppb, liver lesions can occur.