The types of signs exhibited and degree with which swine are affected by mycotoxicosis, or mycotoxin toxicity, is largely affected by not only the type of mycotoxin and concentration in feed, but also by the age and phase of production of the pig. Young pigs and breeding swine are generally the most susceptible to mycotoxins. Additionally, combinations of certain mycotoxins may produce elevated negative effects on performance above that normally expected for each of the mycotoxin levels evaluated individually, and therefore must be considered.
Maximum Tolerable Level of Mycotoxins Commonly Found in Swine Feeds
| Mycotoxin | Maximum tolerable level | Comments |
| Aflatoxins (B1, B2, G1, G2) |
< 20 ppb for human use, dairy feed, feed for immature animals < 100 ppb for breeding swine < 200 ppb for finishing swine (>120 lbs body weight) |
Carcinogenic. Immunosuppressant. Acute signs: anorexia, depression, ataxia, epistasis. Chronic signs: reduced feed efficiency, reduced milk production, icterus, decreased appetite. |
| Zearalenone |
< 1 ppm for young growing pigs < 2 ppm for breeding herd < 3 ppm for finishing pigs and young and old boars |
Estrogenic effects. Swollen vulvas, vaginal or rectal prolapses in pre-pubertal gilts. Enlarged uterus, swollen or twisted uterus, shrunken ovaries. In boars, testes atrophy, enlarged mammary glands, decreased fertility. |
| Deoxynivalenol (vomitoxin) |
< 5 ppm on grain and grain by-products. DON contaminated feedstuffs should not exceed 20% of the diet. < 1 ppm in complete feeds |
Reduction in feed consumption and weight gain are inversely proportional to concentration of DON. High concentrations cause feed refusal and vomiting. |
| T-2 toxin | < 1 ppm | Potent immunosuppressive agent that directly affects immune cells and modifies immune response as a consequence of other tissue damage. Frequent defecation, vomiting, weight loss and feed refusal. |
| Fumonisin |
Not established < 5 ppm (extrapolated from horse data) |
Carcinogenic in laboratory tests using rats. Associated with pulmonary edema in pigs. |
| Ochratoxin | < 200 ppb has been associated with kidney damage in swine | Ochratoxin A is most common and potent. Reduction in growth, feed efficiency, increased mortality, liver and kidney damage. |
| Ergot | < 200 ppb | Vertigo, staggers, convulsions, temporary posterior paralysis, eventual death. Decreased peripheral blood supply. Reduced growth, tail loss, reduced reproductive efficiency of sows. |
Management strategies for utilizing mycotoxin contaminated grain
Once grain is contaminated with mycotoxins, there are no known methods of detoxifying the mycotoxins. Therefore, prevention of mycotoxin production by ensuring proper environmental conditions during storage is essential. However, there are a few management strategies that can be used to minimize the negative effects of mycotoxins on swine health and performance. These include:
Feed the suspect feed or grain to a small number of “test” animals and closely watch for symptoms of mycotoxicosis. Pre-pubertal gilts are often good “test” animals when checking suspected feed for zearalenone (swollen vulvas) and vomitoxin (reduced feed intake).
Collect samples of the suspect grain and send to a commercial analytical laboratory for determination of levels of mycotoxins. Once the levels are known, contaminated grain can be blended with good quality grain to dilute the concentration of mycotoxins below critical levels.
Try marketing the grain to cattle (not dairy cows if aflatoxin contaminated) or sheep producers. Ruminants are less sensitive to mycotoxicosis than pigs and poultry. Uncontaminated grain can then be purchased to avoid health problems and performance reductions.
Consider putting grain through a grain cleaner to remove fines. Broken and damaged kernels are generally highest in mycotoxin contamination because the seeds natural protection has been broken. Avoid feeding grain screenings and fines to swine.
Sodium bentonite and other commercial feed additives have been shown to be effective in minimizing the adverse health and performance effects of pigs fed aflatoxin contaminated feeds. They may also have some benefit in partially alleviating negative effects from other mycotoxins.
Be sure that stored grain is dried and aerated to recommended moisture levels to prevent further mold growth and mycotoxin production. Consider adding commercially available additives or organic acids (propionic, fumaric, citric) to prevent mold growth.
Avoid feeding mycotoxin contaminated grain the breeding herd and young pigs. Grow-finish pigs fed for slaughter are the best candidates for tolerating mycotoxin contaminated grain.