Fumonisin, a toxin that is produced almost exclusively in corn and can be fatal to equine and rabbits, has been found in corn samples from the 2002 corn crop harvested in certain portions of Texas.

The Office of the Texas State Chemist and the Texas Feed and Fertilizer Control Service have analyzed 53 samples of new crop corn for fumonisin since Sept. 19. Forty-nine percent of the corn analyzed is above recommended levels for safe feeding of horses and rabbits.

Recent corn samples that tested positive were from crops around Waco, Austin, Kerrville and Victoria, said Larry Whitlock, supervisor for feed and fertilizer product compliance with the Texas Feed and Fertilizer Control Service.

Because the problem is not confined to a specific region in the state, all corn should be tested for fumonisin prior to being fed to sensitive animals such as horses and rabbits, he said.

Corn screenings (small and broken kernels separated from whole corn during cleaning) generally contain much higher levels of fumonisin than does whole corn. Officials say to be safe, corn screenings should definitely not be fed to horses.

Fumonisin should not be confused with aflatoxin, which is another toxin produced by several molds of the genera of Aspergillus and Penicillium that can occur in corn and also in whole cottonseed, peanuts, grain screenings and the meals made from the oil extracted seed.

Aflatoxin infestation is favored by drought conditions and occurs primarily in corn kernels damaged by insects and drought.

Fumonisin is produced in corn by the fungus/mold Fusarium moniliforme.

Its development is favored by high humidity and overcast skies. These conditions occurred earlier this summer in some parts of the state and triggered the fungal growth, Whitlock said.

Fumonisin can cause leukoencephalomalacia (leuko) in horses, a fatal necrosis of the brain; after an animal has the symptoms, recovery is unlikely. The toxin also causes pulmonary edema (PPE) in swine.

The maximum levels of fumonisin in corn that are considered to be safe for use in animal feeds by the Food and Drug Administration Center of Veterinary Medicine are:

  • Horse, other equines, 5 parts per million (ppm).

  • Rabbits, 5 ppm.

  • Dairy feeds, 5 ppm.

  • Catfish, 20 ppm.

  • Swine, 20 ppm

  • Cattle, sheep, goats and other ruminants older than three months being fed for slaughter, 60 ppm.

  • Poultry (turkey, chickens, ducklings and other poultry fed for slaughter), 100 ppm.

    Ruminants and poultry (includes laying hens, roosters, and bulls), 30 ppm.

  • All others (includes dogs and cats), 10 ppm

To distribute and sell whole corn containing greater than 5 ppm fumonisin or 20 ppb aflatoxin, the firm must have a Texas feed license and all whole grain must be accompanied with a label approved by the Texas Feed and Fertilizer Control Service.

Labeling must list the identity and levels of mycotoxin in a warning statement. Any product containing more than 5 ppm fumonisin cannot be used in dairy feeds or horse feeds, and cannot be used for human foods.

The Office of the Texas State Chemist will continue to survey new crop corn. For updates and further information, contact the Office of the Texas State Chemist/Feed and Fertilizer Control Service at 979-845-1121 or at http://otsc.tamu.edu.