ARTICLE 60 FEED & ADDITIVE MAGAZINE July 2022 and should be part of any risk analysis carried out in feed mills and farms. In fact, in their scientific opinion, the EFSA panel recommends “strict adherence to relevant decontamination and storage processes for all products moved from ASF-affected areas to unaffected areas” (EFSA Journal 2021, doi: 10.2903/j.efsa.2021.6558). These relevant decontamination processes may include heating feed or ingredients to 70°C for 30 minutes. Holding feed and ingredients for a suitable amount of time would be another possibility to ensure save feed. But all these measures have their own drawbacks. This is why in recent years various feed additives have been studied for their potential to mitigate the transmission of swine virus via the feed. These additives include chemical products like formaldehyde and organic acids. However, formaldehyde is highly controversial due to worker safety concerns and application is limited in the EU. Are there more natural and sustainable options? PROPRIETARY PLANT EXTRACT COMBINATION SHOWS HIGH EFFECTIVITY A new phytogenic feed formulation created by Dr. Eckel Animal Nutrition GmbH & Co. KG (Anta®Shield) makes use of powerful bioactive plant metabolites derived, among others, from hops. Some of these components have been cultivated for thousands of years for the very purpose of securing food from pathogens. Modes of action known for these metabolites include the destabilization of bio-membranes from gram positive bacteria. Since the ASF virus is an enveloped virus with a similar outer glycopeptid layer, Dr. Eckel considered the possibility that selected plant metabolites might also be able to reduce the infectivity of the African Swine Fever virus. This would be a significant step in reducing the risk of ASF transmission via feed by natural and sustainable means. PROOF OF CONCEPT An in-vitro study was conducted to test the effect of plant extracts and Anta®Shield against infectivity of African Swine Fever Virus in feed. The results were compared to an organic acid blend. In the screening test, a commercial compound feed for fattening pigs was supplemented with the test substances and infected with African Swine Fever virus in a dose that was considered sufficient for causing infection in swine. After incubation for one, three or seven days, the samples were analysed by cell culture method (haemadsorption dose, HAD50) for observation of infectivity. In a further step, the quantity (Ct values) of ASFV was determined by commercialised Realtime RT-PCR. Figure 1. Effect of selected plant extracts and the final formulation Anta®Shield on viral infectivity in pig feed compared to an organic acid product (Terhorst et al., 2022)
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