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.
Figure 1. Effects of mycotoxins in poultry. Source: BIOMIN
Impact of DON and FUM on the poultry gut 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. According to the BIOMIN Mycotoxin Survey Program 2017 report, 74% of corn samples from the United States were contaminated with DON at an average level (for positive samples) of 893 ppb. Sixty five percent of the same corn samples were contaminated with FUM at an average level of 2,563 ppb. Eighty three percent of the soy bean samples from South America were contaminated with DON at an average level of 1,258 ppb (Figure 2).
Figure 2. Average contamination levels of DON and FUM in US Corn and South American Soybean in 2017.
US Corn (440 samples)
74% contaminated with DON (average = 893 ppb)
South America Soybean (1166 samples)
83% contaminated with DON (average = 1258 ppb)
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 3).
Figure 3. Consequences of mycotoxin contamination on gut condition.
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 programmes 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, Biomin® BBSH 797.
Figure 4. Effect of DON and Mycofix® Select (MSE) on IBV antibody titres in broiler chickens.
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. Mycofix® Select 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.
This article originally appeared in Asian Poultry.