ISSUE FOCUS FEED & ADDITIVE MAGAZINE August 2022 21 mycotoxins is on the rise. The chronic multiple mycotoxin toxicity is comparable to cancer as it is very difficult to diagnose the problem at the early stages. What are so called “Silage” mycotoxins? Many new names for mycotoxin classification have been used lately. “Big 6” mycotoxins refer to the major six mycotoxins that are analysed regularly at feed mills and labs using rapid tests. These are aflatoxins (AF), ochratoxin A (OTA), T-2 toxin, DON, zearalenone (ZEN) and fumonisins (FB) and are measured as “marker mycotoxins” and their presence indicates the potential presence of another 30 to 40 mycotoxins. These mycotoxins along with ergot toxins in the total mixed ration (TMR) can cause health concerns when present in the ration at high concentrations. All these mycotoxins are mainly produced at the pre-harvest stage. What are “Silage” mycotoxins then? “Silage” mycotoxins are those that are predominantly produced during the process of silage fermentation. A well-managed silage will have less production of such mycotoxins as the anaerobic condition will not allow moulds to overgrow and produce mycotoxins. More than 80 micro-aerobic fungal species can grow in silages producing diverse mycotoxins. Penicillium roqueforti, Aspergillus fumigatus and Bysspchlamus are the major moulds in silages and the mycotoxins produced by them have antibacterial and anti-protozoic activity. Since most of the mycotoxins produced during silage fermentation are from the genus “Penicillium”, “Silage” mycotoxins are often referred as “Penicillium” mycotoxins. Some of the examples are roquefortine C, mycophenolic acid, and penicillic acid. What are “Emerging” and “Masked”mycotoxins? In recent times there is a lot of reference to “Emerging” and “Masked” mycotoxins and these mycotoxins add further toxicity to the regular mycotoxins in TMR. “Emerging” mycotoxins such as enniatins and fusaric acid can also have antimicrobial effects in the rumen and this can be one of the reasons for a reduced rumen function and a reduced mycotoxin degradation capacity of the rumen. Some mycotoxins like conjugates of DON, ZEN and T-2 toxin are difficult to detect in feed when routine extraction methods are applied. These so-called “Masked” mycotoxins remain active and are often released by enzymatic and/or microbial activity in the digestive tract. How does mycotoxicosis manifest in dairy cows? Alone and in combination, mycotoxins can threaten dairy cows’ health, rumen function, feed intake, milk yield, milk quality, lameness, and reproductive abilities. Many “mouldy silage syndrome” cases in the field have shown incidences of increased somatic cell counts, undigested faecal feed particles, laminitis, mastitis and ruminitis cases. The reproductive challenges range from increased number of inseminations per conception to retention of placenta or even abortions. Many cases of vaccination failures have been reported with multiple mycotoxins in TMR. How can mycotoxin issues be diagnosed? The major challenge of mycotoxin risk management lies in the diagnosis of the problem and the ability to establish the cause-and-effect relationship. Mycotoxin symptoms in dairy cows can be confounded with that of pathogen challenge, nutritional deficiency, and management related challenges. Although feed mycotoxin analysis has its own sampling error issues, it is the most used diagnostic tool at feed mills and bigger dairy farms. As part of its mycotoxin risk management programme, Selko uses the Mycomaster+ system to check raw materials, feeds, and milk for the “Big 6” mycotoxins and AFM1. Selected feed samples can also be analysed for multiple mycotoxins using LCMS/MS. Based on the mycotoxin concentrations, NutriOpt Mycotoxin Adviser provides customer-specific interpretations on what those concentrations mean and how the toxicity can be managed with the use of right dose of mycotoxin mitigation product (TOXO Range). Is mycotoxin binding strategy good enough? Mycotoxin mitigation strategies in dairy cows
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