ISSUE FOCUS FEED & ADDITIVE MAGAZINE November 2024 43 responsible for a wide range of toxins. However, high humidity during storage can also result in considerable contamination from Aspergillus or Penicillum fungi. Mycotoxins are concentrated on the seeds, placing swine and poultry production at a higher risk, however, calves are particularly vulnerable owing to their underdeveloped rumen – in essence, just as vulnerable as a young monogastric. But it is not only cereals typically in starter feed that are a risk; an array of mycotoxins has also been found in corn silages (Panasiuk, 2018, Reisinger, 2019; Gallo 2022) and grass or whole crop silages (Schenck, 2019; Manni, 2022), which are commonly fed as the calf transitions to a post-weaning forage-based diet. EFFECTS OF MYCOTOXINS ON CALVES The risk posed by mycotoxins is diverse and dependent on the structure of the toxin. For example, deoxynivalenol (DON), a well-researched mycotoxin, is known to inhibit protein turnover in rapidly developing tissues, such as the liver, gastrointestinal tract and immune system – very vital tissues for a growing calf! Toxin effects can be compounded through synergies with other mycotoxins, such as culmorin, which could suppress the immune response, thus enhancing the efficacy of other toxins (Gruber-Dorninger, et al., 2017). Moreover, lesser known, emerging mycotoxins such as enniatins and beauvericin have been shown to have the potential to inhibit development of normal microflora, potentially impacting physiological development of the rumen as well as jeopardizing the protective role microflora play in immune defenses (Krizova, et al., 2021). Recent research using calf epithelial cells demonstrated that nivalenol was more toxic than DON, whereas enniatin B showed similar toxic effect as DON at only 11% higher exposure level (Reisinger et al. 2019). This indicates that damage by mycotoxins to the epithelial cells lining the gastrointestinal tract would result in reduced nutrient absorption as well as increase the risk of particulates or pathogens being able to enter the bloodstream. In terms of animal well-being, it is not only the level of a single mycotoxin that is of concern, more about the array of different mycotoxins that may have synergistic detrimental effects on the animal. WHAT IS IN MY FEED? When it comes to mycotoxin testing, dairy processors are all well aware of the risk of aflatoxin M1 in milk, a potent carcinogenic for humans, when aflatoxin-contaminated feeds are fed. Given the risk, milk is routinely tested to ensure consumer safety. Wider awareness of mycotoxin risk is growing, with much of the focus centered on the few that are regulated in human or animal nutrition, namely, aflatoxin, DON, zearalenone (ZEN), fumonisins, ergot alkaloids and ochratoxin, however, this is just
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