New Fusarium mycotoxins are emerging in dairy cows

While Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEN) and Fumonisins from class B (FBs) have been widely studied, very little in vivo research has been conducted when it comes to these newly emerging mycotoxins. They threaten nutrient digestibility and rumen function in dairy cows.

Previous research has largely focused on how mycotoxins influence milk production of dairy cows, with little focus on how mycotoxins influence cheese production. Prof. Gallo’s presentation will share how an enhanced understanding of the mode of action of Fusarium-produced mycotoxins will be leading to new insights about the threats that mycotoxins pose for dairy cow health and productivity.

New mycotoxins are emerging, mainly produced by Fusarium spp. These newly emerging mycotoxins of dairy cattle are neither routinely determined, nor legislatively regulated. However, the evidence of the incidence of fusarium mycotoxins is rapidly increasing. The effect in adult cattle of some of these mycotoxins has been evaluated well (see Figure 1 below).

For other mycotoxins such as Nivalenol, Fusarenon X, Beauvericin, enniatins and Moniliformin this is not yet the case. Adverse effects differ between the different mycotoxins of dairy cows1 (see Figure 2).

Ruminants are less susceptible than monogastrics because the rumen represents an active defense against mycotoxins. It contains substances that can bind mycotoxins (fibers, yeast walls, bacterial walls) and micro-organisms that can deactivate mycotoxins (protozoa, bacteria). On the other hand, the diets of ruminants are more diversified, increasing the risk of contamination with mycotoxins.

There is a relationship between contamination of corn silage and the metabolic profile of milk. In a study carried out in our lab2, 45 milk samples were classified into five clusters based on the mycotoxin contamination profile of corn silage linked to the corresponding milk samples. Analysis of the metabolomic profile of the milk showed correlations between the quality of contaminated corn silage, that was part of the ration, and the composition of the milk, with the presence of metabolites such as amino acids and peptides, followed by purine, pyrimidines and steroid conjugates.

Exposure to feed with aflatoxin B1 concentrations below the European Union (EU) limit results in aflatoxin M1 concentrations that exceed the EU regulatory limit of 0.05 ppb. A trial was carried out by the CERZOO research center of the University of Piacenza to test the effect of Selko Toxo MX on the excretion of aflatoxin M1 in milk of dairy cows3. The product significantly reduced the transfer of aflatoxin B1 in feed to aflatoxin M1 in milk (see figure 3). Selko Toxo MX also significantly improved feed efficiency measured as milk production per kilogram of dry matter intake, fat corrected milk production per kg of dry matter intake and energy corrected milk per kg of dry matter intake (see figure 4).

Little is known about the adverse effects of commonly found levels of Fusarium mycotoxins on dairy cow performance, especially after a long period of exposure. A trial4 was carried out at the CERZOO research center of the University of Piacenza, to study the effects of moderate levels of Deoxynivalenol (DON), Zearalenone (ZEA) and Fumonisin B1 & B2 (FB) from feeds naturally contaminated with these mycotoxins. The impact of Selko TOXO HP-R on cows exposed to these 3 different Fusarium mycotoxins was tested. The production of energy corrected milk (ECM) was reduced in the animals on a diet with high levels of mycotoxins compared to the negative controls. The animals on Selko TOXO HP-R produced more milk compared to both the negative and positive control groups (see Figure 5).

Fusarium toxins are well studied in animals, but for ruminants still more research is needed to study the effect on feeding behavior, feed digestibility or milk quality parameters. We are starting to understand that Fusarium toxins can impact animal performance and health status, also at low contamination levels (c.a. 1 mg/kg DM of DON on the diet). We need new data for ZEA and FB. A lot of regulated and emerging Fusarium toxins can contaminate feeds, mainly in silage and haylage. These feed ingredients are characterized by complex microflora. In particular, silage can be contaminated by a plethora of Alternaria, Aspergillus, Penicillium and other molds and toxins too. All of these are dangerous or can be used as biomarkers of silage safety and evaluation. We are studying these finding within our Safety Of Silage project. Common protocols for testing effect of Fusarium toxins in ruminants should be adopted. People involve in this topic should work together to increase knowledge level.