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Evaluating chemical mitigation of Porcine Epidemic Diarrhea virus in swine feed and ingredients
Porcine Epidemic Diarrhea Virus (PEDv) is transmitted by fecal-oral contamination. Research has confirmed swine feed or ingredients as potential vectors of transmission so strategies need to be developed to mitigate PEDv presence in feed. Therefore, the objective of this experiment was to evaluate the effectiveness of various chemicals to mitigate PEDv in swine feed and ingredients. Treatments were arranged in a 5 × 4 factorial with 5 chemical treatments and 4 feed matrices. The chemical treatments included: 1) negative control with no chemical addition, 2) 0.003% commercial formaldehyde, 3) 1% sodium bisulfate, 4) 1% sodium chlorate, and 5) 3% organic acid blend. The 4 matrices included: 1) complete swine diet, 2) blood meal, 3) meat and bone meal, and 4) spray-dried animal plasma. Matrices were first chemically treated, then inoculated with 5.6 x 10^4 TCID50/g PEDv, stored at room temperature and analyzed by real-time PCR on d 0, 1, 3, 7, 14, 21, and 42. Data were analyzed by the GLIMMIX procedure of SAS with day as a repeated measure. The analyzed values represent threshold cycle (CT) at which the virus was detected, and thus lower values indicate greater nucleic acid presence, not infectivity. All main effects and interactions were significant, however only main effects are discussed in this abstract due to space limitations (P<0.0001). Both commercial formaldehyde treatment and organic acid addition decreased RNA concentration of PEDv compared to the control (P<0.05), with the commercial formaldehyde treatment being the most effective on d 0 by decreasing the CT by 1.4 to 2.8 CT compared to the control. Feed matrix appears important in retention of PEDv as RNA concentrations were 1.2 to 3.8 CT higher in the complete swine diet and blood meal than meat and bone meal or spray-dried animal plasma on d 0 (P<0.05). Additionally, PEDv stability over time was influenced by matrix as RNA concentrations only improved 0.7 and 2.9 CT by d 42 for spray-dried animal plasma and meat and bone meal, respectively, compared to 4.1 and 5.6 CT for the complete swine diet and blood meal. In summary, time, formaldehyde, and organic acid treatments all enhance the RNA degradation of PEDv in swine feed and ingredients, but their effectiveness varies within matrix. More research is needed to relate RNA concentration to infectivity and to elucidate the appropriate chemical concentration for each feed ingredient or diet.
Keywords: PEDv, chemical treatment, feed matrix, swine