The risk of spreading African swine fever (ASF) virus through feed may be reduced effectively through the use of different feed additives, according to new research conducted at Kansas State University.

ASF is a globally spreading transboundary animal disease that threatens pork production and human food security worldwide, Kansas State said in an announcement.

The research team, headed by Megan Niederwerder, assistant professor of diagnostic medicine and pathobiology in the university's College of Veterinary Medicine, has published a new study, "Mitigating the Risk of African Swine Fever Virus in Feed with Antiviral Chemical Additives," in the scientific journal Transboundary & Emerging Diseases. The study provides evidence that certain feed additives may be effective tools against ASF, the announcement said.

"In 2019, we published the first report of African swine fever virus (ASFV) transmission through the natural consumption of plant-based feed. Our subsequent work has focused on mitigation of ASFV in feed through the use of chemical feed additives and heat treatment," Niederwerder said.

Although feed additives have historically been used to reduce the risk of bacterial contamination in feed, research thus far has not reported efficacy for the inactivation of ASFV in feed ingredients. Niederwerder said there are currently no commercially available vaccines and no effective treatments that can be administered to pigs for ameliorating disease caused by the virus. Thus, ASF control is focused on biosecurity measures to prevent the introduction of the virus into negative countries or negative farms and regions within a positive country. The other method of containment would involve large-scale culling of infected or high-risk animals to contain the spread of the virus.

"Our new research reports novel data evaluating the efficacy of feed additives on inactivating ASFV in an in vitro cell culture model and a feed ingredient transoceanic shipment model," Niederwerder said. "This will provide valuable information to the swine industry with regard to mitigating the risk of potential routes for introduction and transmission of ASFV through feed and ingredients."

Niederwerder and her team examined two different classes of liquid feed additives, including a medium-chain fatty acid-based additive and a formaldehyde-based additive, for efficacy against ASFV in cell culture and in feed ingredients. In general, both chemical feed additives demonstrated evidence of reducing the virus infectivity, with data supporting dose-dependent efficacy, Kansas State said.

While the results of the study are promising, Niederwerder emphasized the need for a multifaceted approach to reducing the risk of ASFV in feed, including sourcing ingredients from countries without the virus when possible, applying holding times to high-risk ingredients and implementing consistent biosecurity protocols at the feed mill.

This study was funded by a grant from the Swine Health Information Center and the State of Kansas National Bio & Agro-defense Facility Fund.