There are no published reports indicating that the African swine fever virus (ASFV) has been detected in feed ingredients or complete feed. This is primarily because there are only a few laboratories in the world that have the biosecurity and analytical capabilities of detecting ASFV in feed. Several in vitro studies have been conducted to evaluate ASFV concentration, viability and inactivation when ASFV was added to various feed ingredients and complete feed. These inoculation studies have shown that some feed matrices support virus survival longer than others and the reasons for this are unknown. Current analytical methodologies have significant limitations in sensitivity, repeatability, ability to detect viable virus particles and association with infectivity. As a result, interpretation of findings using various measures may lead to misleading conclusions. Because of analytical and technical challenges, as well as the lack of ASFV contamination data in feed supply chains, quantitative risk assessments have not been conducted. A few qualitative risk assessments have been conducted, but they have not considered differences in potential scenarios for ASFV contamination between various types of feed ingredient supply chains. Therefore, the purpose of this review is to provide a more holistic understanding of the relative potential risks of ASFV contamination in various global feed ingredient supply chains and provide recommendations for addressing the challenges identified.

Prions and certain endoparasites, bacteria, and viruses are internationally recognized as types of disease-causing biological agents that can be transmitted from contaminated feed to animals. Historically, foodborne biological hazards such as prions (transmissible spongiform encephalopathy), endoparasites (Trichinella spiralis, Toxoplasma gondii), and pathogenic bacteria (Salmonella spp., Listeria monocytogenes, Escherichia coli O157, Clostridium spp., and Campylobacter spp.) were major food safety concerns from feeding uncooked or improperly heated animal-derived food waste and by-products.However, implementation of validated thermal processing conditions along with verifiable quality control procedures has been effective in enabling safe use of these feed materials in animal diets. More recently, the occurrence of global Porcine Epidemic Diarrhea Virus and African Swine Fever Virus epidemics, dependence on international feed ingredient supply chains, and the discovery that these viruses can survive in some feed ingredient matrices under environmental conditions of trans-oceanic shipments has created an urgent need to develop and implement rigorous biosecurity protocols that prevent and control animal viruses in feed ingredients. Implementation of verifiable risk-based preventive controls, traceability systems from origin to destination, and effective mitigation procedures is essential to minimize these food security, safety, and sustainability threats. Creating a new biosafety and biosecurity framework will enable convergence of the diverging One Health components involving low environmental impact and functional feed ingredients that are perceived as having elevated biosafety risks when used in animal feeds.

N-(n-butyl) thiophosphoric triamide (NBPT) (Figure 1) is an active ingredient in nitrogen stabilizer (urease inhibitor), which temporarily inhibits the action of the urease enzyme to improve the efficiency of urea-containing fertilizers. Given the potential for NBPT residues to be present in milk and tissues of dairy cattle, due diligence is needed to demonstrate the safety of NBPT in urea-based fertilizers used on forages and crops intended for consumption by Holstein dairy cows. This study used controlled dosing of NBPT in capsule form to dairy cattle for 28 d, followed by a 14-d depuration phase to assess the potential for residues to exist in milk and tissues of dairy cattle at exaggerated use levels. Fourteen lactating cows were selected for the dosing and depuration phases of the study, based on health, body weight (BW), and milk production. There were four treatment groups: 0 mg NBPT/kg BW (Control) (n = 2 cows), 1 mg NBPT/kg BW (1×) (n = 3 cows), 3 mg NBPT/kg BW (3×) (n = 3 cows), and 10 mg NBPT/kg/BW (10×) (n = 6 cows); levels were based on maximum tolerable amount of urea that a cow can ingest on a daily basis (1×) and the maximum concentration of NBPT commercially used when treating urea (0.1 wt% NBPT in urea). At the end of the 28-d dosing phase, cows were randomly selected for the 14-d depuration phase of the study (one control and three 10× cows). The results showed no NBPT residue is detectable at all dose levels, except that a residue level was above the lower limit of quantitation in a single milk and subcutaneous fat sample in the highest (10×) treatment group, which represents the level of NBPT that would be theoretically present in 10× the lethal dosing of daily consumable urea to a cow. Overall, the study demonstrated that it is unlikely for NBPT residues to be present in cattle milk or edible tissues or to cause negative effects on animal health under good agricultural practice.

Calcium nitrate has been reported to benefit reproductive outcomes in sows and their offspring when administered via the feed (15–19 mg/kg-bw/day) during the periparturient period. Traditionally, dietary nitrate had been considered a methemoglobinemia (MetHb) risk in swine. Similar hazard concerns have existed in humans, but a recent benefit/risk analysis established that nitrate levels associated with well-recognized health benefits outweigh potential risks. A similar benefit/risk perspective in swine was lacking and challenged by sparse published hazard data, often referenced within larger reviews related to all livestock. The objective of this review was to better characterize the potential for adverse health and performance effects reported in the literature for swine consuming nitrate, and to provide metrics for evaluating the reliability of the studies reviewed. Supplemental exposure via feed or drinking water was considered for any life stage, dose, and exposure duration. More than 30 relevant studies, including case reports and reviews, examined calcium, potassium, sodium, or unspecified nitrate salts at doses up to 1,800 mg nitrate/kg-bw/day for exposures ranging from 1 to 105 days. The studies primarily evaluated weight gain, blood methemoglobin levels, or vitamin A homeostasis in sows or growing swine. An extensive review of the literature showed reports of adverse effects at low nitrate doses to be of low reliability. Conversely, reliable studies corroborate nitrate intake from feed or drinking water at levels equal to or greater than EFSA’s no-observed-adverse-effect level (NOAEL) for swine of 410 mg nitrate/kg-bw/day, with no MetHb or other adverse effects on reproduction, growth, or vitamin A levels. Using a weight-of-evidence evaluation, we have moderate to high confidence that the NOAEL for nitrate supplementation in swine is likely between 600 and 800 mg/kg-bw/day. These levels are several-fold higher than dietary nitrate concentrations (19 mg/kg-bw/day) that are known to benefit birth outcomes in sows. This review elucidates the quality and reliability of the information sources historically used to characterize nitrate in swine feed as a contaminant of concern. Results from this evaluation can assist risk managers (e.g., regulatory officials and veterinarians) in consideration of proposed benefits, as well as reassuring swine producers that low-level nitrate supplementation is not anticipated to be a concern.