Guidelines for Feeding Mouldy Corn

US - Marcia Shannon, Missouri state swine nutrition specialist, offers advice to farmers how best to feed this year's mouldy corn, without adversely affecting the health or productivity of farm livestock and poultry.
calendar icon 23 December 2009
clock icon 3 minute read

The best solution is to buy clean grain for swine and dairy as they are most susceptible. Thus, some mouldy feed may be fed to beef cattle. Feeder cattle should be able to safely consume levels five to 10 times higher than swine and dairy. Thus, ruminants older than four months can withstand 10 to 20ppm of vomitoxin. Signs of toxicity with vomitoxin/deoxynivalenol (DON) are usually feed refusal or feed intake reduction. At concentrations of 5 to 10ppm, vomitoxin vomiting is observed in swine.

Zearalenone concentrations should not exceed 2ppm in growing and finishing pigs. Signs of toxicity that may be observed in swine with zearalenone are a disrupted estrus cycle, enlarged mammary glands, and swollen vulva.

If contaminated corn must be fed, the following table lists FDA advisory levels for vomitoxin/deoxynivalenol (DON) in animal feed.

Advisory levels for vomitoxin/deoxynivalenol (DON) in animal feed

Corrective steps

  • clean mouldy grains, remove fines and light weight grains suspected of contamination
  • dilute mould- or mycotoxin-contaminated corn with mould-free grains
  • if mouldy corn is fed to pigs, a reduction in feed intake and growth rate will be approximately 10 per cent for each 1 ppm of vomitoxin in the diet
  • no zeolites are effective in alleviating vomitoxin toxicity
  • if mild contamination is suspected, increase the nutrient levels by 5 to 20 per cent of the diet to help compensate for the reduced intake
  • store mouldy grain separately at 13 per cent moisture and feed before summer temperatures rise.

Calculate the maximum inclusion level of mouldy corn

Maximum inclusion rate (%) = safe level ÷ level in corn DM × 100
If corn analysis is 5ppm DON then: 1 ÷ 5 × 100 = 20% maximum inclusion level based on DON level

Despite these calculations, poor palatability of mouldy corn may lower feed intake. If in doubt, be conservative and watch for problems!

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