| Scott Fritz, DVM, ABVT Toxicologist Beef Cattle Institute Kansas State University Scottfritz@vet.k-state.edu |
Sources
Mycotoxins are secondary fungal metabolites that are produced by mold that colonizes damaged grains. Grains are the most common source, but occasionally certain forages can also be an issue.
Mechanism
There are only a few mycotoxins with recognized clinical effects, FDAs guidance tables are presented here.
Mycotoxins and Regulatory Limits
- CVM focuses on 5 major mycotoxins in the U.S.:
- Action levels – aflatoxins – Compliance Policy Guidance Manual Section 683.100
- Aflatoxin contamination has legal requirements for the sale of commodities
- Guidance levels – fumonisins
- Advisory levels – vomitoxin (DON)
- No action, guidance or advisory levels for ochratoxin A or zearalenone have been established by the FDA in animal feeds (these 2 mycotoxins are handled on a case-by-case basis.
Action levels for total aflatoxins in livestock feed
| Class of Animals | Feed | Aflatoxin Level |
| Finishing beef cattle | Corn and peanut products | 300 ppb |
| Beef cattle, swine or poultry regardless of age or breeding status | Cottonseed meal | 300 ppb |
| Finishing swine over 100 lb. | Corn and peanut products | 200 ppb |
| Breeding cattle, breeding swine and mature poultry | Corn and peanut products | 100 ppb |
| Immature animals | Animal feeds and ingredients, excluding cottonseed meal | 20 ppb |
| Dairy animals, animals not listed above, or unknown use | Animal feeds and ingredients | 20 ppb |
| Food and Drug Administration guidance levels for fumonisins in animal feeds. | ||
| Mycotoxin | Use | |
| Total fumonisin | 5 ppm (1 ppm) no more than 20% of diet) | Equids (horses, mules, donkeys) and rabbits |
| 20 ppm (10 ppm) (no more than 50% of diet) | Swine and catfish | |
| 30 ppm (15 ppm) (no more than 50% of diet) | Breeding ruminants, breeding poultry and breeding mink | |
| 60 ppm (30 ppm) (no more than 50% of diet) | Ruminants older than three months being raised for slaughter and minks raised for pelt production | |
| 100 ppm (50 ppm) (no more than 50% of diet) | Poultry being raised for slaughter | |
| 10 ppm (5 ppm) (no more than 50% of diet) | All other species or classes of livestock and pet animals | |
Advisory levels for vomitoxin (DON) in livestock feed
| Class of Animal | Feed Ingredients & Portion of Diet | DON Levels in Grains or Grain By-products and Complete Diet** |
| Ruminating beef and feedlot cattle older than 4 months | Grain and grain by-products* | 10 ppm (10 ppm)** |
| Ruminating dairy cattle older than 4 months | Grain and grain by-products not to exceed 50% of the diet* | 10 ppm (10 ppm)** |
| Ruminating beef and feedlot cattle older than 4 months, and ruminating dairy cattle older than 4 months | Distiller’s grains, brewers grains, gluten feeds, and gluten meals* | 30 ppm (10 ppm beef/feedlot)** ( 5 ppm dairy)** |
| Chickens | Grain and grain by-products not to exceed 50% of the diet | 10 ppm (5 ppm)** |
| Swine | Grain and grain by-products not to exceed 20% of the diet | 5 ppm (1 ppm)** |
| All other animals | Grain and grain by-products not to exceed 40% of the diet | ppm (2 ppm)** |
| *88 percent dry matter basis ** complete diet figures shown within parentheses | ||
Zearalenone: there are no FDA guidelines for Zearalenone.
| Class of Animal | hyperestrogenism | anestrous | infertility |
| Ruminating beef and feedlot cattle younger than 6 months | >1 ppm | 3 ppm | 12 ppm |
| Chickens | >1 ppm | 3 ppm | |
| Swine | >1 ppm | 3 ppm | |
| All other animals | >1 ppm | 3 ppm |
- Produced by Fusarium sp. (primarily F. graminearum)
- Common substrates are corn, wheat, barley, occasionally oats
- Production favored by high humidity and low temperatures
- Estrogenic mycotoxin, swine most susceptible – vulvar swelling in gilts
- Toxicity related to reproductive system
- No FDA action, advisory or guidance levels established for zearalenone in US feed
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