Mycotoxins, Silent killers
Mycotoxins, secondary toxic metabolites produced from fungi, are present in poultry feed all the time. Even when analysis results show that mycotoxin contamination is below guideline levels suggested by major agriculture countries, there can still be cause for concern. So what does it mean if mycotoxins are present in feed at low levels? Any mycotoxins present in feed are delivered straight to the gastrointestinal tract (GIT) of the birds, the organ most affected by mycotoxins. The GIT is the most important organ 
for converting feed into energy, and its ability to function properly is directly linked to poultry productivity. The GIT is the biggest immune organ in the body system. Among the major mycotoxins, DON (deoxynivalenol), ZEN (zearalenone) and FUM (fumonisins) are often overlooked when considering their impact on poultry health and productivity since their clinical symptoms are not usually obvious or visible. However, there have been a number of scientific and commercial trials that prove these Fusarium mycotoxins are closely related to some important poultry diseases.
Mycotoxin Contamination Situation in South Asia
BIOMIN has conducted the Mycotoxin Survey Program annually since 2004. The accumulated number of samples is already over 75,000, which makes the program the largest worldwide data pool for mycotoxin analyses. In 2017, the analysed number of samples hit a record high. Overall, 2017 was another high-risk year for mycotoxins in Asia, similar to 2016. The infographic (Figure 1) shows where the major mycotoxins were found throughout Asia in 2017. Taking a closer look at the results from South Asia or India, Aflatoxin (Afla) is still the biggest threat if we also consider the percentage contamination above the risk threshold. The prevalence of FUM and Ochratoxin A (OTA) in South Asia was the highest of all the Asian sub regions (Figure 2). However, Afla has been always the centre of attention that it is relatively well counteracted.
Impact of DON and FUM on the poultry gut
More problematic mycotoxins are rather FUM and DON. Unfortunately, in India the awareness of these Fusarium mycotoxins is low. DON is a known protein synthesis inhibitor and can interfere with the metabolism of high turn-over cells such as skin cells (epithelial cells), hepatic cells, immune cells and intestinal epithelial cells. Some of the most frequent sub-clinical symptoms of DON contamination in feed are the reduction in feed intake, wet-droppings and a reduction in vaccine efficacy. On the other hand, FUM blocks the synthesis of complex sphingolipids that play a pivotal role in protecting nerves, muscles and membranes.
Several poultry feeding trials clearly show that Fusarium mycotoxins such as DON and FUM lead to an up-regulation of pro-inflammatory cytokines in the gut. Seventy percent of immune system is located in the gut, promoting a rapid mucosal inflammatory response, even when mycotoxins are present at low concentrations in feed. Tight junction proteins in the intestinal epithelium are also regulated by such cytokines. Loosened tight junctions can cause “leaky gut syndrome” resulting in pathogens and toxins entering the blood stream and moving to target organs. As a result, the permeability of intestine is increased and the frequency of intestinal disorders and disease outbreaks can consequently increase as well (Figure 4).
Impaired immunity at low mycotoxin contamination levels
DON and its co-occurrence with FUM are known to modulate the immune function. One good example is the reduction in the number of antibody titres against vaccine programs in poultry. Several research results have shown that DON and FUM reduce antibody response to Newcastle Disease (ND) and Infectious Bronchitis Virus (IBV). In one experiment conducted in Austria, the feeding of a DON-contaminated diet decreased serum antibody titres against the IBV vaccine (Figure 4) compared to the control diet. 
However, the antibody titres for IBV improved when the DON-contaminated diet group was fed with Mycofix Select (MSE), a mycotoxin deactivator that includes the DON-biodegrading bacteria, BBSH 797.
Mycotoxin risk management in poultry
When it comes to counteracting mycotoxins, the poultry industry tends to think of “toxin-binders” first. However, clay mineral binders are not an effective answer to all major mycotoxins. Especially not against Fusarium mycotoxins since their structures are not suitable for adsorbing by binders. Biotransformation using microbes and enzymes is the most effective strategy. It provides reliable protection for birds against Fusarium mycotoxins by biodegrading mycotoxins into non-toxic metabolites. The transformation is fast, specific and irreversible.
In addition to biotransformation, a bioprotection strategy is also important. Variety of feed additives is available that contains plant and algae extracts to provide a hepato-protective effect and to overcome the immune suppression caused by mycotoxins. A combination of different strategies can counteract the negative effects of mycotoxins in poultry more completely, especially in cases of multi-mycotoxin contamination with the poorly absorbed Fusarium mycotoxins in poultry feed.
Feed additive refers to Mycofix Select, to know further about the product or technology, the author can be contacted at eileen.han@biomin.net
