Due to their gastrointestinal and immunosuppressive effects, fumonisins can seriously compromise swine performance. Fumonisin contamination in swine is difficult to detect mainly because it tends to occur at subclinical levels—necessitating measurement of the sphinganine—sphingosine (Sa/So) ratio, a scientifically recognized biomarker for identifying fumonisin exposure in pigs.
Multiple studies conducted in recent years report the extreme sensitivity of swine to fumonisin contamination even at levels below the European guideline of 5,000 parts per billion (ppb). Direct examples of the immunosuppressive effects of fumonisins in swine are the development of porcine pulmonary edema (PPE) and the decreased resistance to certain pathogens such as Pasteurella multocida.
Fumonisins and Pasteurella multocida
There is a link between fumonisins and increased susceptibility to P. multocida, a pathogen responsible for respiratory disorders, e.g. lung inflammation. A 2005 study highlighted how the sensitivity of piglets exposed to P. multocida increased exponentially in the presence of fumonisins. During the trial period, piglets exposed to the pathogen alone did not show significant symptoms such as lung lesions and a decrease in weight gain. However, animals challenged with P. multocida in combination with dietary fumonisins at a concentration of 0.5 mg/kg of body weight displayed delayed growth, coughing and a higher cell count in the bronchoalveolar lavage fluid (BALF). An increase in the number of lymphocytes and macrophages was reported as well. Greater lung lesions in the form of subacute interstitial pneumonia were detected in the group that received both the fumonisins and the pathogen.
Worldwide concentrations of fumonisins in 2017 have already reached average values that can affect animal production (see Table 1 and Figure 1). Maize and maize by-products such as dried distillers grains with solubles (DDGS) and corn gluten typically run a higher risk of fumonisin contamination. Average fumonisin levels in maize exceeded 2,500 ppb: a concentration that can significantly affect pigs (see Table 2 and Figure 2).
Mycotoxin binders cannot sufficiently address fumonisin challenges in real-life settings. They involve a neutralization process known as adsorption, adhering to toxins in order to limit their entrance into an animal’s bloodstream. However, mycotoxin binders have shown an extremely low binding capacity of fumonisins at pH 6 and pH 7 common in a pig’s gut.