Fumonisins have been detected in various feed commodities in different parts of the world and together with deoxynivalenol, are considered as one of the most frequently occurring contaminants of animal feed. They can reduce pig health, performance and profitability.

Legal situation

Currently, the European Union imposes statutory limits for levels of aflatoxins (AFLA), ochratoxin A (OTA), zearalenone (ZEN), deoxynivalenol (DON), and fumonisins (FUM) in animal feed. According to the European Union directive 2006/576/EC, the recommended maximum level of fumonisins in pig feed (with an assumed 88 percent dry matter content) may not be more than 5 mg/kg irrespective of animal age. 

Fumonisin effects

Fumonisins are mainly produced by the fungi Fusarium verticillioides and Fusarium proliferatum and are among the most frequently occurring mycotoxins in agricultural commodities like maize, rice, and sorghum. Since 1989, fumonisins have received greater attention due to the fatal disease outbreak among pigs fed Fusarium verticillioides-contaminated maize in the Midwestern and Southeastern parts of the United States; an outbreak which led to the death of thousands of pigs. 

Fumonisins do not only cause various diseases such as porcine pulmonary oedema, immune-suppression, and hydrothorax, but also, by impairing the animal’s health status, fumonisins cause significant economic losses in swine production. Besides, we have to keep in mind the effects of multi-mycotoxin contamination of animal feeds and the exposure of individuals to more than one mycotoxin at the same time. This should definitely be taken into consideration when planning any mycotoxin risk management program on the farm. 

In addition, fumonisins disrupt sphingolipid metabolism and block the synthesis of complex sphingolipids from sphinganine (Sa) and sphingosine (So). As a result, Sa and So accumulate in tissues. This has a double significance:

1. Sphingolipids participate in many different processes in the body, and this allows fumonisins to negatively influence, directly or indirectly, a variety of organs (e.g., the liver, kidney and brain), systems (e.g., the vasculature and nervous system) and processes (e.g., fatty acid metabolism and uptake of folic acid) in the organism of the affected animal.

2. As Sa and So accumulate, they can be used as biomarkers to indicate fumonisin contamination. The interruption of sphingolipid metabolism by fumonisins leads to the production of oxidative damage and lipid peroxidation, cell damage, and apoptosis. Fumonisins also reduce the uptake of folic acid; and the resulting folic acid deficiency could also explain the association of fumonisin exposure with neural tube defects.

Fumonisin interactions with diseases

Today there is a growing appreciation regarding the interactive effects of mycotoxins and different diseases. There are several studies which have confirmed that mycotoxins can have primary and secondary interactions with certain diseases. In the case of fumonisins the effects can be:

1. Fumonisins are known to variably modulate immunity and host resistance (primary interaction).

2. Fumonisins interfere with post-vaccinal immunity (secondary interaction) and as such, reduce the resistance of animals to infectious diseases.

In the case of pigs fed FUM-contaminated feed, it was observed that there was an increase in the intestinal colonisation of pathogenic Escherichia coli bacteria. It was also noted that the presence of fumonisins in compound feed induced the porcine reproductive and respiratory syndrome virus (PRRSV), a viral disease caused by a RNA virus of the Artreriviridae family responsible mainly for reproductive disorders and embryonal mortality in pigs. 

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Fumonisins also can affect the phagocytic ability of alveolar macrophages to eliminate S. typhimurium and Pseudomonas aeruginosa, which increases the susceptibility of pigs to diseases caused by the above-mentioned pathogens. Simultaneous ingestion of fumonisin B1 and Pasteurella multocida reduced the growth rate of pigs, induced coughing and enhanced the extension of lung lesions, leading to sub-acute interstitial pneumonia. Feeding FUM-contaminated feed might also lead to inappropriate vaccination responses. 

This was observed in the decreased level of antibodies against Mycoplasma (post-vaccination) in pigs fed FUM-contaminated diets for 28 days. Furthermore, numerous experiments have confirmed the link between porcine pulmonary oedema and fumonisin exposure.

Economic losses 

Fumonisins are an important issue in swine production because pigs are considered to be very sensitive towards their negative effects. In practical terms, fumonisins can significantly decrease the feed intake and growth of pigs depending on the concentration, exposure, and presence of other mycotoxins in the feed. 

Several studies have examined fumonisins with different inclusion ratios in pig feed. The impact of different mycotoxins on pig performance was examined, in a study based on 85 research reports that were published in the past 40 years. 

The results of this meta-analysis have shown that DON (-18 percent) and AFLA (-11 percent) had the highest impact on reduced feed intake, while there were not statistically significant differences for FUM and ZEN. Nevertheless, among animals fed contaminated feeds, feed conversion ratio was found to increase for DON (+25 percent), AFLA (+12 percent) and FUM (+6 percent). 

As fumonisins suppress the immune function in pigs, this may eventually:
a) reduce resistance to infectious diseases,
b) re-activate chronic infections, and
c) reduce therapeutic and vaccine efficiency.

In addition, in the presence of fumonisins, pigs are more susceptible to secondary or simultaneous infectious and parasitic diseases, which consequently lead to reduced performance and reproduction.

Conclusions

Fumonisins are known to negatively affect pig health and performance. Pigs fed contaminated feed will suffer from depressed feed intake and growth, and negative feed efficiency. 

Fumonisins not only reduce pig immunity directly, but they also appear to facilitate the effects of other diseases. At the end, animal health and welfare are reduced, and this always depresses profitability.