Pre-harvest recommendations for limiting mycotoxins in feed and grain
- Clean inside and outside of grain bins and dryers.
- Prior to storage, check the condition of the bin for possible water leaks, and clean it properly by removing dust, dirt, leftover grain and other foreign material.
- Crop rotation in many regions or tillage can reduce the risk of Gibberella ear rot in corn and Fusarium head blight of wheat. These practices have little effect on other corn ear rots.
- Some corn hybrids are more resistant to ear rots than others, but overall, resistance to ear rots is not widely available.
- Control of second-generation European corn borers and other insect pests of corn ears can greatly reduce infection by Fusarium and Aspergillus.
- Few wheat varieties have high levels of resistance to Fusarium head blight (scab). Plant moderately resistant varieties when available. Planting several varieties that differ in maturity will reduce the risk of disease to the whole crop.
- As with any crop pest, early detection through scouting and early harvest can reduce serious losses and avoid crises. Decisions on handling moldy grain should be made before it is harvested. After harvest, spoilage can occur quickly if delays result from indecision.
- If extensive ear rot development is observed (10% or more of the ears with more than 10-20% mold), the field should be harvested as soon as moisture content reaches a level that can be harvested. Even if some drying costs are incurred, this will be less expensive than loss of crop value due to mycotoxins and resulting feeding problems.
Post-harvest recommendations for limiting mycotoxins in feed and grain
The crops should be allowed to mature in the field to the following moisture contents: shelled corn, 23-25%; ear corn, 20-25%; small grain, 12-17%; and soybeans, 11-15%.
- Harvesting equipment should be adjusted to minimize damage to seeds or kernels and allow for maximum cleaning. Cracked or broken seeds or kernels are more susceptible to mold invasion.
- Upon storage, dry the grain to 13-14%, if possible, within 48 hours. Long-term storage can be achieved at a uniform moisture of 18% for ear corn; 13% for sorghum, wheat and shelled corn; and 11% for soybeans.
- After drying, store under cool temperatures (below 40° F).
- If outdoor temperatures are still high at harvest, cool the grain in cycles with every 10-15-degree fall in average outdoor temperatures and run the fans during cool, dry nights.
- Pay attention to the air dew point temperature when cooling, as low dew points indicate good conditions for cooling.
- The time it takes to cool an entire bin depends on the airflow rate per bushel. A large drying fan (1 cfm/bu) will take 15 hours or so, while a smaller aeration fan (0.1 cfm/bu) will take at least 150 hours (close to a week).
- Every few weeks check the condition of the grain for temperature, wet spots and insects.
How to test for harmful mycotoxins in cattle
The presence of a fungus known to produce toxins is not proof that the grain contains injurious levels of toxin. Collecting a representative sample of grain for chemical analysis at a laboratory may be a good investment to determine mycotoxin presence.
- When sampling grain, particular attention should be given to the sampling procedure because sampling error will be the greatest source of variation in the analytical procedure. This variation is primarily due to the uneven distribution of the mycotoxin contaminated kernels within a lot of grain or feed. The ideal sampling procedure should assure the highest probability of detecting mycotoxins even when contamination is low.
- There are a few ways to sample grain, such as collecting an aggregate sample as the grain is moving in a stream in or out of bins, or by using a probe sampler. Because mold growth usually occurs in spots in the grain lot, the best sampling is done on recently blended lots of grain. With both sampling methods, the collected grain is pooled into a large aggregate sample that represents the lot · For shelled corn, it is recommended that the aggregate sample be about 10 pounds. The aggregate sample is coarsely ground at the lab. Most analytical procedures need only about 25 grams (0.9 ounces) of ground corn, so it is important that the aggregate sample be thoroughly mixed after grinding. A one- or two-pound sub-sample is then taken, and it is more finely ground. From this sub-sample, a final sample is taken for analysis.
- Contact your local KENT representative for support in analyzing and managing your mycotoxin risk.
- If the mycotoxin is present in the feed, it may be blended on farm to reduce the toxin to acceptable levels in small lots, and it may be a good idea to channel the feed to animals that are more tolerant. Important: Blending is not an approved practice by the FDA for interstate commerce.
Learn the effects of harmful mycotoxins in cattle and other livestock
Mycotoxins Reported in Detrimental Feed Concentrations (ppm = parts per million) This table summarizes the main mycotoxins that affect livestock production with species, upper limit safety and their effects noted.
Zearalenone
| Species | Concentration | Duration | Effect |
|---|---|---|---|
| Swine | |||
| Prepubertal gilts | 1–5 ppm | 3–7 days | Hyperestrogenism, prolapse |
| Open gilts, sexually mature | Anestrus, pseudopregnancy | ||
| Bred sows | 15–30 ppm | 1st trimester | Early embryonic death, small litters |
| Juvenile boars | 10-50ppm | Indefinite | Reduced libido, small testicles |
| Mature boars | 200 ppm | Indefinite | No effect |
| Cattle | |||
| Virgin heifers | 12 ppm | Open Heifers | Reduced conception |
| Dairy cows | 50 ppm | Open Cows | Reduced conception |
| Poultry | |||
| Broilers & Turkey poults | 200 ppm | Indefinite | No effect |
Deoxynivalenol (vomitoxin, DON)
| Species | Concentration | Duration | Effect |
|---|---|---|---|
| Swine | |||
| Feeder pigs | 1–3 ppm | 1–5 days | Reduced feed intake |
| Feeder pigs | 5–10 ppm | 1–5 days | 50% reduction in feed intake, vomiting |
| Feeder pigs | 10–40 ppm | 1–5 days | Complete feed refusal, vomiting |
| Sows | 3–5 ppm | Gestation or lactation | Lower fetal weights or no effect |
| Cattle | |||
| Feeder cattle | 10 ppm | Indefinitely | No effect |
| Dairy cows | 6 ppm | 6 weeks | No effect or slightly reduced feed intake |
| Dairy cows | 12 ppm | 10 weeks | No effect on milk production |
| Poultry | |||
| Broilers & Turkey poults | 50 ppm | Indefinitely | No effect |
Fumonisins (FB1 and/or FB2)
| Species | Concentration | Duration | Effect |
|---|---|---|---|
| Horses | |||
| All classes and ages | >10 ppm | 30 days | Liver damage, leukoencephalomalacia, death |
| Swine | |||
| All classes and ages | >25 ppm | 30 days | Reduced gain and feed efficiency, mild liver damage |
| All classes and ages | >50 ppm | 10 days | Reduced gain and feed efficiency, moderate liver damage |
| All classes and ages | >100 ppm | 5 days | Severe pulmonary edema, death |
| Cattle & Sheep | |||
| All classes | >100 ppm | 30 days | Slightly reduced gain, mild liver damage |
| All classes | >200 ppm | 14 days | Reduced feed intake and gain, moderate liver damage |
| Turkeys | |||
| All classes | >100 ppm | 21 days | Reduced feed intake and gain, mild liver damage |
FDA’s guidance level for total fumonisins in corn and corn by-products (not to exceed 20% of the diet) used for equine and rabbit feed products is 5 ppm (1 ppm in finished feed).
Aflatoxins (ppb = parts per billion)
| Species | Concentration | Effect |
|---|---|---|
| Swine | ||
| All classes and ages | 200 ppb | Slow growth, reduced feed efficiency |
| All classes and ages | 400 ppb | Liver damage and immune suppression |
| Feeder Cattle | ||
| All classes and ages | 400 ppb | Tissue residues |
| All classes and ages | 700 ppb | Mild liver damage, reduced growth and feed efficiency |
| All classes and ages | 1,000 ppb | Moderate liver damage and weight loss |
| All classes and ages | 2,000 ppb | Severe liver damage, jaundice, death |
| Dairy Cows | ||
| Lactating cows | 20 ppb | Detectable aflatoxin in milk |
| Lactating cows | 1,500 ppb | Decreased milk production |
| Poultry | ||
| Broiler chicks | 210 ppb | No effect |
| Turkeys | 250 ppb | Reduced growth |
| Broiler chicks | 420 ppb | Lose weight, moderate liver damage after 3 weeks |
| Horses | ||
| All classes and ages | 400 ppb | Liver damage and immune suppression |
Munkvold, G., Osweiler, G., Hartwig, N. 1997 Iowa State University Ext. PM-1698 FDA has set a maximum limit of 20 ppb for aflatoxins in commercial grains used in feed for immature animals, dairy animals, poultry, horses, turkeys, and for unknown use.
*Information was derived from The Ohio State University (OSU) website that is a cooperative effort among numerous land-grant universities. Also, included in this OSU document are preventative practices pre-harvest and post-harvest, as well as steps and methods for testing.
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