Research has demonstrated that swine feed can be a fomite for viral transmission and certain feed additives can effectively reduce viral contamination. However, additional information is needed to evaluate the efficacy of additives when feed is inoculated with more than one virus. The objective of this study was to evaluate the efficacy of two feed additives for mitigation of porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV) when inoculated individually or together. Feed additives included: 1) no treatment, 2) 0.33% commercial formaldehyde-based product (Sal Curb, Kemin Industries, Des Moines, IA), and 3) 0.50% medium chain fatty acids blend (MCFA; 1:1:1 ratio of C6:C8:C10, Sigma Aldrich, St. Louis, MO). Samples were inoculated with PEDV and PRRSV alone or together at an inoculation concentration of 106 TCID50/g for all viruses. Once inoculated, feed was stored at ambient temperature for 24-h before analyzed via qRT-PCR. For samples inoculated with PEDV or PRRSV alone, a qRT-PCR assay was used which was designed to detect PEDV or PRRSV nucleic acid. For co-inoculated samples, an assay was designed to independently detect both PEDV and PRRSV within a single reaction. For PEDV alone, there was marginally significant evidence that feed additives resulted in differences in cycle threshold (Ct) value (P = 0.052), but no evidence was observed for pairwise differences. For PRRSV alone, formaldehyde increased Ct compared to the untreated control and MCFA treatment (P < 0.05). For co-infection of PRRSV and PEDV, MCFA and formaldehyde increased Ct (P < 0.05) in comparison to non-treated feed. In summary, formaldehyde increased Ct values in feed when contaminated with PRRSV while both mitigants increased Ct value in feed when co-inoculated with PRRSV and PEDV.

中文翻译：

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PSVI-7 单独或联合接种猪流行性腹泻病毒和猪繁殖与呼吸综合征病毒的饲料缓释剂功效评价

研究表明，猪饲料可以成为病毒传播的污染物，某些饲料添加剂可以有效减少病毒污染。然而，当饲料中接种了一种以上的病毒时，还需要额外的信息来评估添加剂的功效。本研究的目的是评估两种饲料添加剂单独或一起接种对缓解猪流行性腹泻病毒 (PEDV) 和猪繁殖与呼吸综合征病毒 (PRRSV) 的效果。饲料添加剂包括：1) 未经处理，2) 0.33% 商业甲醛基产品（Sal Curb，Kemin Industries，Des Moines，IA），和 3) 0.50% 中链脂肪酸混合物（MCFA；1:1:1 比例C6:C8:C10, Sigma Aldrich, St. Louis, MO)。样品单独或一起接种 PEDV 和 PRRSV，所有病毒的接种浓度为 106 TCID50/g。接种后，将饲料在环境温度下储存 24 小时，然后通过 qRT-PCR 进行分析。对于单独接种 PEDV 或 PRRSV 的样品，使用设计用于检测 PEDV 或 PRRSV 核酸的 qRT-PCR 测定。对于共同接种的样品，设计了一种检测方法，以在单个反应中独立检测 PEDV 和 PRRSV。仅就 PEDV 而言，有轻微显着的证据表明饲料添加剂会导致循环阈值 (Ct) 值的差异 (P = 0.052)，但没有观察到成对差异的证据。对于单独的 PRRSV，与未处理的对照和 MCFA 处理相比，甲醛增加了 Ct (P < 0.05)。对于 PRRSV 和 PEDV 的合并感染，与未经处理的饲料相比，MCFA 和甲醛增加了 Ct (P < 0.05)。总之，甲醛在被 PRRSV 污染时会增加饲料中的 Ct 值，而当与 PRRSV 和 PEDV 共同接种时，两种缓解剂都会增加饲料中的 Ct 值。