Feed & Additive Magazine Issue 15 April 2022

ISSUE FOCUS 30 FEED & ADDITIVE MAGAZINE April 2022 BOOSTING NATURAL IMMUNITY WITH FRA® C12 Dry New findings reveal that FRA® C12, known for its antiviral activity, could help support natural body defence. It improved sow and piglet performance on a farm suffering from a severe PRRSv outbreak. In the study, conducted by FRA®melco, the addition of FRA® C12 Dry to the diet resulted in a reduced pre-weaning mortality, lower use of medication and significantly reduced PRRSv shedding in weaned piglets. Sow productivity has increased tremendously during the last decades and brought some serious challenges with it, like sow longevity and the viability and uniformity of piglets. Moreover, porcine reproductive and respiratory syndrome virus (PRRSv) is still one of the most relevant viruses affecting pig farming, causing variable clinical signs. Sow farmers commonly face a substantial increase of abortions, number of stillbirths, pre-weaning mortality and respiratory diseases in weaners and growers. In addition, in PRRSv-infected pigs the susceptibility to secondary bacterial or viral infections increases dramatically. For instance, concurrent infections with Streptococcus suis are often reported. The prevalence of secondary infections together with direct losses caused by PRRSv are the reason for the major economic impact of this viral syndrome. HOW PRRSv SABOTAGES THE IMMUNE SYSTEM Like all viruses PRRSv needs host cells to multiply. The virus inserts its genetic material into the host cell and hijacks its machinery to create many viral copies. One of the main target cells for PRRSv replication are porcine alveolar macrophages, found in the lungs. These macrophages are big white blood cells that ‘eat’ foreign material, like bacteria and viruses, and remove dead cells. They serve as the first line of defence against inhaled harmful microbes. When attacked by PRRSv their function is directly impaired. Moreover, in PRRSv-infected animals the production of pro-inflammatory cytokines, which signal the immune system to do its job, has shown to be limited. The reduced level of these important messengers allows the PRRS virus to escape from the host immune response. Hence, the immune system is not fully activated, and viral clearance is not initiated. It allows PRRSv to multiply easily inside the host, like sows or piglets. This immunosuppressive effect of PRRSv may also contribute to the increased risk of secondary infections, like Streptococcus suis. Olga Dansen, MSc Head of R&D FRA®melco B.V.

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