MYCOTOXINS ▶▶▶
Revealing the mycotoxin risk in straw
Analyses of wheat and barley straw samples reveal a potential mycotoxin risk in straw. Producers would be advised to pay attention to straw management and mycotoxin risk.
DR RADKA BORUTOVA, DVM, PHD, EUROPEAN TECHNICAL SUPPORT MANAGER, ALLTECH
E 25%
3.5 0-9
22.9%
mycotoxins per sample on average
20% 17.1% 15.7% 15%
number of mycotoxins range
95.7% 81.4%
samples containing mycotoxins
5%
samples with 2 or more mycotoxins
4.3% 26 10% 5.7% 4.3% 2.9% 1.4% 0% 0 2 4 6 ▶ ALL ABOUT FEED | Volume 30, No. 3, 2022 8 14.3% 11.4%
ach year, comprehensive mycotoxin testing pro- grammes are caried out across Europe, USA and Canada that help reveal the mycotoxin threat in newly harvested crops. The results of these surveys
are designed to provide accurate mycotoxin risk insights to feed and livestock producers who will be making nutritional decisions during the coming feeding season. For the first time, as part of the European programme, a representative sample of wheat and barley straw samples (n = 70) were col- lected and analysed from Danish farms. Wet weather in Den- mark both pre and post-harvest had raised concerns about grain and forage quality there. Delayed and wet harvests, where straw remains in the field for long periods inevitably results in poorer quality straw, and in many cases, it is visibly mouldy. What’s more, if straw has been harvested and baled after rainfall, it can be further contaminated by mould spores
Figure 1 - Distribution of number of mycotoxins in straw samples collected in Denmark.
Distribution of number of mycotoxins in selected samples
from the soil. Dark grey moulds may be clearly seen, and the straw can be dusty. However, moulds are not always visible, so it is not safe to assume that if straw looks clean and free of mould, it is free of mycotoxins.
Higher mycotoxin risk levels in Danish straw
Although not commonly seen as a mycotoxin risk, the re- sults of straw testing at the lab reveal that 84% and 70% of all straw samples were contaminated with deoxynivalenol (DON) and emerging mycotoxins, respectively. Similar to grain samples, as can be seen in Figure 1, the multiple mycotoxin risk is also present in straw, with 3.5 mycotoxins per sample detected on average. Over 95% of samples con- tained mycotoxins, with over 80% containing two or more. The average concentration of DON was 1,542 ppb, with a maximum of 10,914 ppb. A noticeable trend in recent years is the growing presence of emerging mycotoxins. Of the 70 samples analysed, almost 70% contained this group and included specific mycotoxins such as beauvericin, monili- formin, phomopsin A, alternariol, enniatin A and B. Fusaric acid also belongs to the emerging mycotoxins group and was detected in 20% of samples. It can have synergistic in- teractions with deoxynivalenol and fumonisins. As a result, the toxicity symptoms of these other mycotoxins may be observed more readily or may be more severe when fusaric acid is present. When Alltech’s Risk Equivalent Quantity (REQ) metric is applied to these results, over 50% of the samples are deemed to be of moderate to higher risk for pigs and calves (Figure 2).
How can this poor-quality straw impact livestock? There is limited data on the consumption of straw bedding by pigs. Some data suggests that weaned pigs consume around 1.6 kilograms per day. In sows, approximately 22% of their total feed intake is the straw provided for bedding, though this can increase up to 30% when fresh straw is provided daily. Based on the levels of deoxynivalenol found
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