Mycotoxin survey for feed and feed ingredients in Asia Pacific
Mycotoxins are secondary metabolites produced by toxigenic fungi, which result in mycotoxicosis when ingested, affecting animals' health adversely. The prevalence of mycotoxin contaminations in feed and agricultural commodities may consequently lead to economic losses and pose a perpetual challenge in the feed industry. Hence, it is imperative to incorporate mycotoxin testing of feed and feed commodities as part of the mycotoxin risk management program, so that the effects of mycotoxins on animals can be mitigated.
In our survey, two main methodologies were adopted. Firstly, the conventional method using High-Performance Liquid Chromatography (HPLC) is employed for complex matrices, which involves the use of an immunoaffinity column for clean-up and thus minimizes the interferences prior to injection. Secondly, a lateral flow test device which utilizes lateral flow immunoassay technology was also used (Figure 1).
Figure 1. Schematic diagram of conventional HPLC (Left) and lateral flow immunoassay method (Right)
With state-of-art equipment, Customer Laboratory Services (CLS) from Kemin Animal Nutrition and Health, Asia Pacific, conducted a mycotoxin survey to understand the risk of mycotoxin contamination in Asia. This survey covers over 2000 mycotoxin analyses from April 2016 to August 2019, with a total of 450 feed samples and 612 agricultural commodities collected across Asia. Five commonly found mycotoxins, namely Total Aflatoxins (Afla), Zearalenone (ZEA), Deoxynivalenol (DON), Fumonisins B1+B2 (FUM) and Ochratoxin A (OTA) were determined quantitatively. The breakdown of the analyses was presented in this survey (Figure 2). The feed commodities were further stratified to corn, Distiller's Dried Grain with Solubles (DDGS) and others, which include soya bean meal, meat and bone meal, rice bran, wheat and barley (Figure 3).
Figures 2 and 3. Mycotoxin analysis conducted, and the total number of samples analyzed (Left to Right)
OVERVIEW IN ASIA
High occurrences of mycotoxins in feeds and agricultural commodities were observed where at least 70% were contaminated with the Afla, ZEA and FUM (Table 1). The highest level of contamination in the samples was FUM, with an average concentration of 1,703 ppb.
Table 1. Mycotoxin contamination in all samples received in Asia from April 2016 to August 2019
SHIFT IN MYCOTOXIN OCCURRENCE
Throughout the 3 year study, it is revealed that there is a significant shift in mycotoxin contamination to more of Fusarium sp. toxins in both feed and commodities. It is profoundly influenced by the effects of climate change, bringing mycotoxin contaminations to preharvest crops. The ensuing increase in occurrences for ZEA, DON and FUM are seen in this study (Figure 4). In addition, high occurrence of Afla and OTA in samples remains a concern, as it is predominantly attributed to the tropical (and subtropical) climate and post-harvest storage conditions in Asia. Under these conditions, mold activities with these mycotoxin contaminations are encouraged (Figure 4).
MYCOTOXIN CONTAMINATION IN FEED AND AGRICULTURAL COMMODITIES IN ASIA
The overview of mycotoxin contamination in feed, corn, corn by-product and other
agricultural commodities in Asia is presented (Table 2). From these data, though it is indicative that respective Fusarium mycotoxins ZEA, DON and FUM greatly contaminated the feed and commodities, the majority of samples were within limits stated in the most stringent European Union Commission Recommendation (2006/576/EC). Contrastingly, no amount of mycotoxin is considered safe. One of the major effects on animals' gut health is caused by the ingestion of low to moderate levels of mycotoxins, leading to a perturbation of gut microbial balance in animals hence impairing their intestinal functions.
Table 2. Mycotoxin contamination in feed samples received from Asia
Note: BD: Below Detection Limit. The limits of quantification (LOQ) for Afla <3ppb, DON <250ppb, ZEA <25ppb, FUM <250ppb and OTA <10ppb
It is noteworthy to mention that the existing legislations or recommendations only consider a single mycotoxin exposure data. They do not address the concerns arising from mycotoxin co-contamination. From the samples received across Asia, 76% of them were contaminated with more than one mycotoxin (Figure 5). The co-contamination of mycotoxins is likely to result in synergistic effects where the adverse impacts of mycotoxins are magnified. Synergism occurs when the combined impacts of the mycotoxins are greater than the additive impacts of the mycotoxins.
MYCOTOXIN MANAGEMENT PROGRAM
In general, prevention methods employed during crop growth, harvesting, and storage can only decrease the potential risk of mycotoxin contamination to a certain degree. Therefore, detoxification procedures after harvest are a key area of focus. The elimination of mycotoxins in grains and feed occurs via three methods: physical, chemical, and biological processes in the grains, in the feed, and inside the bodies of animals.
Adsorbent materials are commonly used in feed as additives to counteract mycotoxins by binding them inside the animals, which then excrete them in feces. Among the major mycotoxins, Afla has a polar functional group with a planar structure that is well suited for adsorption. Also, OTA and FUM can be categorized as polar mycotoxins and both at pH 3.0 and pH 7.0 levels, the excellent binding efficacy against them has been well-documented. Mycotoxin Risk Management tools, which consist of analysis, diagnosis and detoxification, are available to mitigate the negative impacts of mycotoxins on the animals' health and performance.
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Article made possible through the contribution of Hui Ru Tay, Agnes Thng, David Tey and Kemin Animal Nutrition and Health, Asia Pacific