Fumonisins are a group of harmful fungal metabolites mainly produced by Fusariumproliferatum and F. verticillioides and which, when present in feed, can have a serious impact on the performance of poultry flocks.
These toxins are a major contaminant of corn (maize), which is a major constituent of poultry diets. Fumonisins were not previously considered a major threat to the poultry industry, however, research over the past 15 years has revealed significant fumonisin interactions with birds’ immune and digestive system.
Metabolic and immunologic impact
From the 1970s to late 1990s, many trials were conducted in chicken and turkeys using highly contaminated feed (50 to 300 ppm), but they failed to show any effects on the performance of birds. However, as given doses used in these trials did not reflect realistic contamination levels in the field, the focus on fumonisins in poultry gained little interest.
Yet evidence has emerged more recently showing that fumonisins, occurring at subclinical concentrations, might predispose birds to metabolic and immunologic disorders. New technologies allowing the analysis of subtle parameters may account for these findings.
Recent data has shown that ingestion of 10 ppm fumonisins in feed affects the expression of proteins related to pro- and anti-inflammatory responses in the intestinal tract of broiler chickens. At the concentration limit of 20 ppm in poultry, set by the European Union, fumonisins induce higher excretion of Eimeria strains, the parasites responsible for coccidiosis.
Considering the high density of birds in large-scale operations, the ingestion of contaminated feed with fumonisins may promote transmission of the parasite between birds.
A separate experiment using similar concentrations of fumonisins reported an effect on proteins in the intestine of chickens involved in drug metabolism. This might alter the pharmacokinetic characteristics of several drugs.
Together, these findings suggest that the intestinal tract of birds is highly sensitive to exposure to fumonisins.
Inside the chicken
Fumonisins block the synthesis of complex sphingolipids that play an important role in protecting nerves, muscles and membranes. As a consequence, the free sphingoid bases sphinganine (Sa) and sphingosine (So), both highly toxic to most cells, accumulate in tissues leading to severe cell damage and cell death.
Based on this, the sphinganine-sphingosine ratio (Sa/So) is used as a biomarker for fumonisin exposure, with an increase indicating a negative impact of fumonsins on the bird. This ratio is routinely assessed in blood or liver. For the first time in poultry, it has been shown that this ratio also has an effect in the intestine, confirming that fumonisins can affect the metabolism of intestinal cells.
The occurrence of fumonisins is ubiquitous and not limited to a specific climate.
The 2014 Biomin Mycotoxin Survey results show that 73 percent of 1,071 corn samples analyzed tested positive for fumonisin contamination with an average of positives of 2,914 ppb.
The second largest group in this survey comprised finished feed, with 63 percent of 1,676 samples analyzed testing positive for fumonisins, with an average contamination of 926 ppb. Soybean, wheat and other grains showed a lower presence of fumonisins compared with corn (see table).
Poultry species have been considered to be less susceptible to fumonisins, lacking clinical signs of impairment even when feed contamination levels are high, yet research in the field of mycotoxin impairment has recently focused on subclinical effects, and suggests that the intestinal tract of birds is very sensitive to fumonisins exposure. Studies in various poultry species indicate that fumonisins represent a major risk to animal health.
Effective mycotoxin risk management, including novel approaches to biotransformation, is essential to help birds face fumonisin-induced impairment of the immune and digestive system, and to help maximize performance.