Encouraging new research from Pipestone Veterinary Services suggests it may be possible to secure feed against PEDv. The study, which appeared in BMC Veterinary Research, says “preliminary evidence that a means to ‘biosecure’ feed against a globally significant virus may be possible.”
Kemin Industries, headquartered in Des Moines, Iowa, funded the research study at the request of Pipestone Veterinary Services and has marketed the product used in the study (Sal CURB), for nearly 20 years. It is a formaldehyde-blended product designed to maintain Salmonella-negative status of complete feeds and feed ingredients for up to 21 days. Formaldehyde is an ingredient regulated by the FDA as an antimicrobial and can be used as part of a comprehensive risk management program.
Lead author of the study, Dr. Scott Dee, director of research at Pipestone Veterinary Services, noted, “Now more than ever, sound science and public/private partnerships are needed to provide the most effective options for risk management in this challenging situation.”
Sal CURB is an FDA-approved liquid antimicrobial used to control Salmonella contamination in poultry and swine diets. To test its effect against PEDV, feed treated with SalCURB was spiked with a stock isolate of PEDV (Ct = 25.22), which PEDV-naïve piglets were allowed to ingest via natural feeding behavior (ad libitum) for a 14-day period. For the purpose of a positive control, a separate group of piglets was allowed to ingest non-treated feed, also spiked with stock PEDV (Ct = 25.22). A negative control group received PEDv-free feed.
Clinical signs of PEDV infection (vomiting and diarrhea) and viral shedding in feces were observed in the positive control group 2–3 days post-consumption of non-treated feed. In contrast, no evidence of infection was observed in pigs fed the treated feed or in the negative controls throughout the 14-day study period. In addition, the SalCURB-treated feed samples had higher (p < 0.0001) mean PEDv Ct values than samples from the positive control group.
Based on the results of the bioassay, feed treated with the product prevented infection and clinical disease in naïve piglets. In contrast, pigs allowed to ingest non-treated feed spiked with PEDv became infected. While both the treatment and the positive control feed contained a similar level of PEDv immediately post-processing (day 0), there was a significant difference in mean Ct at the end of the sampling period (day 15) across the 2 groups. While Ct values in treated feed changed over time, values detected in the positive control feed samples remained relatively constant.
These data provide proof of concept that feed treated with Sal CURB can serve as a means to reduce the risk of PEDv infection through contaminated feed. Furthermore, the results from the positive control group provide additional proof of concept regarding the ability of contaminated feed to serve as a risk factor for PEDv infection of naïve piglets.
Additional Research Needed
An acknowledged limitation was that the results are based on very small populations of pigs housed under experimental conditions and cannot be extrapolated to large-scale commercial farm conditions until further testing can be conducted. In addition, the study was not designed to answer questions which still remain regarding the liquid antimicrobial product, such as the duration of activity against PEDV, its effects on other viral pathogens, its effect on dietary nutrients and the logistics of application and daily use. Still, this is the first published research providing evidence that a means to “biosecure” feed against a globally significant virus may be possible.
“Every day pork producers and consumers feel the impact of PEDv,” said Daryl Schraad, Kemin president of the animal nutrition and health division in North America. “Study findings such as those discovered by Pipestone Veterinary Services are needed to lessen the devastation of this virus.”
Since its initial detection in May 2013, porcine epidemic diarrhea virus (PEDV) has spread rapidly throughout the US swine industry. Recently, contaminated feed was confirmed as a vehicle for PEDV infection of naïve piglets. This research provides in vivo data supporting the ability of a liquid antimicrobial product to reduce this risk.