11 mycotoxin survey lessons to reduce poultry feed risks

Mycotoxin contamination is a serious threat. Survey data shows which fungal species present the major potential risks to flock health in poultry feed.

Krugloff, BigStockPhoto.com
Krugloff, BigStockPhoto.com

The presence of toxic fungal metabolites has long been associated with impaired health and performance in poultry flocks. However, several specific lessons for the poultry industry have emerged after analysis of a decade of worldwide mycotoxin occurrence data.

1. Much of the risk to broilers and laying hens comes from mycotoxin-producing Fusarium species infecting crops in the field. One major example is head blight of cereals, caused by F. graminearum and F. culmorum, both able to produce deoxynivalenol (DON) and other trichothecene toxins as well as zearalenone (ZEN). The same fungi can cause ear rot in corn, as can the fumonisin (FUM)-producing F. verticillioides. These three mycotoxins have presented the greatest risk to poultry over the past 10 years.

2. Sometimes, mycotoxin levels can increase in corn and cereals in one season but quite often the trends are different (Figure 1). A risk assessment based on the proportion of raw commodity and finished feed samples for which at least one mycotoxin was above the risk threshold (Table 1) reveals an obvious fluctuation from year to year.

3. The risk for finished feed often tracks the pattern of corn for six monthly fluctuations in each of the four continents represented in Figure 1. This is to be expected, given corn’s prominence in poultry diets. Depending on the subregional feed materials, the levels in feed will also be affected by cereal mycotoxin levels as well as other feed sources.

Global Mycotoxin Risk 1

For most years in most regions, the probability of encountering mycotoxins is greater than 50 percent.

4. Binders may not be sufficient to fully guard against common mycotoxins. Although a proven product can safely and effectively bind aflatoxins, an adsorption strategy is less effective against deoxynivalenol, zearalenone and fumonisins. Given the occurrence of these major mycotoxins, an effective biotransformation strategy may be preferred.

5. Weather conditions largely determine the field-grown mycotoxin risk. Rainfall has a particular influence as it is conducive to fungal infection, but timing is important.

The 2016 cereal harvest in much of Europe registered high levels of DON due to rainfall at the crucial flowering time of crops. The risk in southern Germany was, for instance, generally greater than in northern Germany, due to the difference in weather patterns. The risk in 2016 European corn did not see the same dramatic increase because the rainfall did not coincide so much with the silking period of corn, although it still remained at a slightly higher risk for mycotoxins compared with cereals in the latter half of the year. Regional variance in weather – a key driver of mycotoxin patterns – means vigilance is warranted in the face of common and unexpected threats.

6. Given the changes in levels and types of mycotoxins that occur over time and between even localized parts of regions, monitoring is important and strategies to address mycotoxin threats present should be proven for the broad range present.

7. A combination of deoxynivalenol and fumonisins can worsen the incidence and severity of coccidiosis in poultry.

Mycotoxin Risk Thresholds Poultry2

Mycotoxins may impair poultry health and performance at levels lower than regulatory or guideline maximum levels.

8. Low risk does not mean no risk. Even within a relatively small country such as Austria, there are large differences in DON levels in corn that have been statistically linked with rainfall occurrence around the silking period. This means that, even in a year of low average occurrence, we still need to be mindful of the presence of mycotoxins in individual feed batches.

9. Certain ingredients can surprise. Soya materials are generally considered a low risk for the major mycotoxins, but high levels were registered in some regions of South America in 2016. This was largely related to very wet harvest conditons. Occasional high levels of mycotoxins can be found in soya in other regions also, so caution is also warranted with this feed type.

10. Regional surprises also occur. The detailed examination of the increased mycotoxin risk in 2016 South American finished feed (Figure 2) reveals that fumonisins and deoxynivalenol posed the greatest risk. The rise in their prevalence included sharp increases in samples with very high contamination.

11. Distillers dried grains with solubles (DDGS) merits monitoring. DDGS are a high-value, but reasonably low-cost, feed source. The mycotoxin content in DDGS, however, increases by a factor of three compared with the original corn or cereal. For this reason, manufacturers are often selective about grain quality, but the survey results reveal that 90 percent of DDGS samples had at least one mycotoxin above the risk threshold. If DDGS are used as a significant portion of the diet, then there is added cause for careful monitoring.

Changing Risk Of Finished Feed South America 3

The occurrence and concentrations of fumonisins and deoxynivalenol rose considerably from 2015 to 2016.

 

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