ISSUE FOCUS 20 FEED & ADDITIVE MAGAZINE August 2022 Unlike what is perceived in the animal industry, the risk of mycotoxin exposure is the highest for dairy cows. Their TMR contains not only grains and protein sources, but many unconventional by-products, silages, hay, haylage, and green grass/pasture. The consumption of such TMR induces multiple mycotoxin toxicity and therefore, the intervention strategy must be holistic, practical, and multi-pronged. The global animal industry considers mycotoxins as a major threat to the health and performance of pigs and poultry. Does everyone in the animal industry believe the same for dairy cows? Probably not, as there is a myth in the animal industry that dairy cows can handle mycotoxins effectively due to their rumen microbial activity. Why can dairy cows succumb to mycotoxins? Although rumen microbes can reduce the toxicity of some mycotoxins, they cannot eliminate the problem completely. Not all mycotoxins are equally degraded in the rumen. Modern high-yielding dairy cows are fed with high-starch diets which compromises the detoxification capacity of rumen microbes. For some mycotoxins, like zearalenone (ZEN), rumen degradation may increase the toxicity. Among mycotoxins not completely inactivated in the rumen, only aflatoxin (AF) B1 is transferred into dairy milk as AFM1 in levels that create a public health concern. Research has demonstrated that cows genetically selected for high milk production may also excrete higher levels of AFM1 into milk. The global dairy industry must also be aware that among all production animals, dairy cows are exposed to a greater number of mycotoxins. How is that possible? Looking at the diets of poultry and pigs, it is mainly comprised of grains such as wheat and corn, and protein sources such as soybean meal, and sunflower meal. What about dairy cows? In addition to the feed ingredients mentioned above, TMR of dairy cows contains silages, hay, haylage, green grass/ pasture and many other unconventional ingredients. Such complex TMR composition results in multiple mycotoxin challenges in dairy cows. Although it varies across the globe, in general high-quality raw materials are prioritized for humans, pets, pigs, poultry and dairy cows, in that order. What else can make dairy cows more susceptible to mycotoxins? It is very well known that dairy cows are exposed to low levels of multiple mycotoxins for an extended period. Acute toxicity due to mycotoxins such as ergot toxins and T-2 toxin is lower now but chronic toxicity due to relatively lesser toxic mycotoxins such as DON, fumonisins and silage SHOULD WE WORRY ABOUT MYCOTOXINS IN DAIRY COWS? A holistic look at multiple mycotoxin management in TMR Dr. Swamy Haladi, DVM., PhD Global Programme Manager Mycotoxin Risk Management Selko Feed Additives
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