Abstract
Abstract To reduce the risk of feed-based pathogens causing disease, some feed manufacturers quarantine high-risk ingredients before their inclusion in feed. Data exists that confirms this practice is effective, but there is no information about swine pathogen survival in mill environments. This objective of the study was to determine survival of African swine fever virus (ASFV) in swine feed and mill surfaces. A pilot-scale feed mill manufactured a batch of ASFV-free feed (Batch 1), followed by a batch inoculated with ASFV (5.6×104 TCID50/gram; Batch 2). Then 4 subsequent ASFV-free batches were manufactured (Batch 3-6). After each batch,10 feed samples were aseptically collected in a double ‘X’ pattern. During feed manufacturing, 24 steel coupons were placed on the floor of the manufacturing area and feed dust settled on them during the milling process and overnight. Feed samples and steel coupons were stored at room temperature. Three of each were randomly selected and analyzed for ASFV DNA on d 1, 3, 7, 14, 28, 60, 90, and 180. The interaction of batch and day impacted (P = 0.023) the number of genomic copies detected per gram of feed. There were no differences of genomic copies/g in early batches; but the quantity of detectable ASFV decreased with increasing storage time after collection. In Batches 4-6, the greatest quantity of ASFV was detected on d 1, but the lowest quantity was detected on d 7, 60, and 28 or 180 for Batches 5, 6, and 7, respectively. There was no evidence (P = 0.433) of ASFV degradation on environmental coupons over the 180-d storage period. This study found that quarantine time can help reduce, but not eliminate ASFV in feed over time. However, ASFV survives on feed manufacturing surfaces for at least 180 d. Additional research is necessary to evaluate the viability of detected virus to cause illness.
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