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Performance Thieves - Molds and Mycotoxins
Incidence: Usually present at variable levels in most feed grains. Feed grains are the single largest source of mold and mycotoxin contamination in prepared feeds. Incidence stems from mold promoting environmental conditions while in the field, and during storage prior to feeding.
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Fusarium, Altermaria and Cladosporium molds develop during growth in the field. Fusarium molds are present in the soil, and plants are contaminated as they grow in infected fields.
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Aspergillus molds develop during grain and feed storage. Thrive in hot, moist locations within the stored grain.
Dusty grain, hot spots in the bin, bridging and caking, feed refusal, off-aroma and abnormal color are all associated with mold growth and potential mycotoxin development.
International Ag Labs, Fairmont, Minnesota reported that corn tested at their lab in 1999 had the following mycotoxin levels:
| 1999 Corn Crop |
|
1999 Corn Mold Counts |
| Mycotoxin (ppb) |
Range |
Average |
|
(MycoCurb treated vs. untreated) |
| Zearalenone |
0-900 |
140 |
|
Average treated = 240 cfu/g |
| Aflatoxin |
0-25 |
9 |
|
Average untreated = 850 cfu/g |
| Vomitoxin (Deoxynivalenol) |
0-3 |
1.25 |
|
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The above results clearly indicate that molds and mycotoxins were present in feed corn used by Omega Nutrition clients. However, the molds necessary to produce the mycotoxins were reduced by an average of 72% in Martin County, Minnesota, when a mold inhibitor was applied. Because of the high mold and mycotoxin levels in the untreated corn, it was highly likely that pig performance was affected unless preventative steps were taken.
Feed Effects: Similar to the physical effects on stored grains, mold growth in complete feeds are associated with feed refusal, off-aroma dustiness, caking and bridging. Molds and mycotoxins alter the nutritional profile of grains by altering the nutrient content of the contaminated grain as the mold grows and either binds or uses the kernel nutrients for its own purposes.
B-vitamin content changes, with Thiamin and Niacin reductions of up to 25 to 46% Amino Acid content also changes, with lysine levels reduced by up to 45%
Pig Performance Effects: Mycotoxin effects vary by type of toxin and level in the feed, however, common effects associated with mycotoxin contaminated grain include, but are not limited to: reduced growth performance, food refusal, swollen vulvas, pseudopregnancy, delayed estrus and rough hair coat. Additionally, some mycotoxins are associated with increased disease susceptibility and may intensify or lengthen the duration of the disease challenge effects.
Disease susceptibility increased by 50 - 70% in pigs simultaneously affected by aflatoxin and swine dysentery. -
According to Dr. Dick Odgaard, DVM, Kemin Industries, one undetected pseudopregnancy for 114 days results in over $400 of added cost, even if the sow is not culled. This does not include the lost opportunity cost of that sow’s productive career if she is culled.
9.5 pigs (lost potential) at $30/pig $285
114 days of feed $34
114 days depreciation $73
114 days labor, interest expense $24
Total $416
The effects of lost feed efficiency due to wasted feed and feed refusal can be tremendous. A 0.1 improvement in feed efficiency can result in savings of $0.25 to $0.45 per nursery pig and $0.70 to $0.90 per finishing pig.
Preventative Treatments:
Avoid threshing and handling procedures which crack or break the kernel. Cracked or broken kernels allow the mold access to the kernel interior, providing a nutrient source for further growth. Screen grain prior to storage to reduce or eliminate broken kernels, thus limiting the nutrients available for mold growth. Remember, the majority of mold contamination occurs in cracked or broken kernels. Prior to storage, empty bulk bins should be cleaned and checked to remove old grain or feed which could harbor mold and inoculate the new grain or feed. If molds and mycotoxins were present, it is advisable to clan and fumigate the grain and feed storage bulk bins, or clean and disinfect grain and feed storage bulk bins with a 5:1 diluted bleach spray, allowing the bins to dry. -
It is imperative that correct moisture levels are maintained during storage to prevent mold growth and mycotoxin development.
Commercial mold inhibitors can also be applied as the grain is moved to storage. Remember, mold inhibitors will not eliminate mold and mycotoxins already present, they eliminate further mold and mycotoxin development. Only store enough complete feed for 10 days, 14 days maximum. Keep feeders adjusted and cleaned so that only fresh feed is constantly available. Proper feeder management also minimizes moisture wicking up into the unfed feed and causing mold growth. Eliminating wasted feed will improve group feed efficiency. Remember, each 0.1 improvement in feed efficiency is worth $0.25 to $0.45 per nursery pig and $0.70 to $0.90 per finishing pig. -
If molds and mycotoxins are present in feedstuffs and complete feed, a mycotoxin binder is advisable to “bind-up” the mycotoxin in the gut and prevent absorption into the pig, allowing them to pass through the pig without affecting performance.
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Several commercial binders are available, with varying costs and degrees of effectiveness. Determination of the appropriate binder for the specific mycotoxin in your feed can be made with help form your Omega Nutrition representative.
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When considering the costs/benefits of mold inhibitors versus binders, it is important to recognize that mycotoxin binders typically reduce the availability of other nutrients. Because of this effect, dietary nutrient density can be increased to compensate for this, however, this increases diet cost.
The negative effects of mycotoxins on pig performance can be controlled. Implementation of good agronomic and nutrition practices will effectively limit mold growth and mycotoxin development. An approach involving all stages of feed grain production and storage is necessary to obtain the most effective control.
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