Introduction

Mycotoxins are toxic secondary metabolites produced by molds. Feeding materials can become contaminated with mycotoxins because of mold growth during harvest in the field or at storage. Mold growth can be classified as field molds and storage molds, and the main fungi families that can cause mycotoxicosis in animals are Aspergillus, Fusarium, and Penicillium. Compared to temperate climates, mycotoxins are more frequently found in hot and humid areas like the South-East Asia region where the environment is favorable for the growth of molds. Mycotoxins give rise to many different biological effects in animals such as toxicity in liver and kidney, defects in central nervous system and estrogenic responses that lead to lower animal performances. When mycotoxins are ingested at high or low levels, they may cause mycotoxicosis which can result in acute or chronic symptoms in animals. Acute mycotoxicosis can lead to death while chronic effects are linked with reduced feed intake, reduced growth and development, immunosuppression, cancer and other "slow pathological conditions". More than 500 mycotoxins have been identified, and five of them, specifically Aflatoxin, Deoxynivalenol, Zearalenone, Fumonisin and Ochratoxin were found to cause considerable deterioration of the animals' health which may result in high economic losses. This survey would discuss about the mycotoxins produced by the most significant species of the three genera in relation
to feed safety.

Methodology

Mycotoxin occurrence

Table 1 shows the mycotoxin analysis survey conducted on the feed ingredients and complete feed samples received from Asia. Fumonisin B1, Aflatoxin B1, and Deoxynivalenol were the most frequently occurring mycotoxins in the feeding stuff.

Maximum action and rejection limits of different mycotoxins - Guidelines by GMP+ (Good Manufacturing Practices+)

No amount of mycotoxin can be considered safe. At times only a few mycotoxins are analyzed, and the presence of one mycotoxin may suggest the presence of other mycotoxins.The GMP+ Feed Certification scheme integrates the requirements for quality management system (ISO 9001) and HACCP to ensure compliance in keeping mycotoxin levels below specified limitsto produce safe feed.Maximum permissiblelimitsof mycotoxins in animal feed (as seen in Table 4) were established based on the recommended regulatory limits imposed by the European Community in 2006/576/EC and the guidance value in 575/2011.

Co-occurrence of mycotoxins

Co-contamination of mycotoxins can cause adverse effects on animals as the interactions can be additive or synergistic. The complexity of mycotoxin interactions can vary according to the animal species, the type of mycotoxins, the level of contamination and the length of exposure.

Maize and complete feed for poultry and swinethat have contamination values above the permissible limit were evaluated for the co-occurrence of mycotoxins. In general, the highest co-occurrence rates recorded were the complete feed samples for poultry and swine due to the combination of various contaminated feed ingredients. As the incidence of Aflatoxin B1 in Asia's feeding stuffis high, the most frequently co-occurring mycotoxin combinations found incomplete feed for poultry were Aflatoxin B1 + Fumonisin B1 and mycotoxins found in feed for swine were Aflatoxin B1 + Zearalenone and Aflatoxin B1 + Deoxynivalenol.

The three-year survey indicated that the feed ingredients and finished feed were contaminated with mycotoxins (secondary metabolites of molds). In Asia, AFB1, ZEA, DON, and FUM B1 were present in more than 50% of the finished feed and co-occurred in majority of the samples. Effective prevention and control measures must be implemented to reduce the risk of mycotoxin formation in the field and during storage. Mold inhibitors can be incorporated to prolong the stability of the feed and feed ingredients during storage. In addition, a broad-spectrum mycotoxin binder can be a comprehensive solution to reduce the toxicity risk of mycotoxin co-occurring in the feed samples from North and South-East Asia.