A study funded by the Swine Health Information Center Wean-to-Harvest Biosecurity Research Program, in partnership with the Foundation for Food & Agriculture Research and Pork Checkoff, recently defined biosecurity practices used across wean-to-harvest sites through an industry-wide questionnaire and developed a rapid-risk assessment tool for producers. Led by Dr. Gustavo Silva at Iowa State University, the study assessed current bioexclusion practices among a diverse group of producers across swine-producing states in the US. Further, the study developed methods that veterinarians, production managers, and producers could implement to improve on-farm biosecurity. Findings showed that biosecurity on wean-to-harvest sites is inconsistent across the industry and that tools for increasing biosecurity could include relatively simple practices such as bench entry.
Find the industry summary for project #23-029 here.
Two primary objectives of the study were to 1) assess the current bioexclusion practices used at wean-to-harvest sites across the US, ensuring a diverse group of producers from different swine-producing states are included and 2) develop a tool that veterinarians, production managers, and producers can use to assess biosecurity on their sites quickly.
Data to characterize current biosecurity practices was collected through a questionnaire completed by 21 herd veterinarians, representing production systems and independent producers. The questionnaire was developed with input from industry experts and was comprised of 69 questions on bioexclusion practices, covering site characteristics, vehicle movements, people movement, manure removal, water entry, and sanitation. A weighted method ensured the results reflected all respondents’ answers.
Results of the questionnaire included data representing 15.7 million pigs across 3,680 sites in 13 states. Of the 3,680 sites, 10.3% were nurseries, 52.9% were finishing sites, and 36.8% were wean-to-harvest sites. Most farms (93.3%) reported using all-in-all-out and mortality disposal was mostly off-site (65.3%). Close to half (47.3%) of all employees visited more than one site daily. While most sites have shower facilities (63.8%), fewer sites require employees to shower in or out (57.6% and 56.9%, respectively). Manure is removed about 1.5 times per year, often by third-party companies. Most sites rely on well water (87.7%) with most not performing any water treatment (64.7%).
Questionnaire results on transport biosecurity revealed trucks hauling pigs are generally washed and disinfected, with 100% of trucks hauling weaned pigs cleaned between loads. For feeder trucks, 60.9% are washed and 63.9% are disinfected between every load. For market hog trucks, 78.3% are washed, and 52% are disinfected between every load.
For developing the biosecurity assessment tool in Objective 2, researchers enrolled 139 wean-to-harvest sites to assess biosecurity practices and their relationship with lateral introduction of PRRSV, PEDV, PDCoV, and TGEV. Farms were required to be stable or negative for PRRSV and key enteric viruses, including PEDV, PDCoV, and TGEV, to participate. Participating producers were asked to complete a biosecurity questionnaire with 115 questions covering risk events, biosecurity management practices, herd demographics, truck sanitation, and farm location.
The 139 sites were across nine companies in six states, including 44 nurseries from three companies, 44 finishers from three companies, and 51 grow-finish sites. Findings demonstrated that PRRSV outbreak rates were highest in grow-finish sites (27/44; 61.4%), followed by wean-to-finish (27/51; 52.9%) and nurseries (15/44; 34.1%). No outbreaks of PEDV or coronaviruses were reported in nurseries or wean-to-finish sites, but grow-finish sites had a 2.3% break rate for coronaviruses and a higher rate for PEDV (11.4%).
Additional key findings included that nursery sites had 92% lower odds of reporting a PRRSV outbreak than finishers, and biosecurity practices like bench entry, truck washing, and downtime between loads reduced outbreak risk. Hauling animals with unknown status for PRRSV increased the odds of reporting an outbreak by 12 times, stressing the need for careful animal health monitoring before transportation.
While most sites involved in the study reported implementing biosecurity measures such as vehicle washing and employee training, researchers found gaps remain, especially in communication and compliance auditing. Information gained from Objective 2 revealed that nursery sites have a significantly lower risk of PRRSV outbreaks than grow-finish sites. This emphasizes the need for stronger biosecurity in the finisher phase. Simple, cost-effective measures like bench entry—where employees change footwear or clothing before entering different areas—can help reduce the spread of PRRSV and are relatively easy to implement. Researchers note more data is needed to refine biosecurity recommendations and help producers improve their practices, enhance surveillance, and build a more resilient industry.
Information collected through Objective 1 allowed researchers to understand and characterize the implementation frequency of bioexclusion practices on wean-to-harvest sites. Results are aligned with the reality of biosecurity measures being better established and more frequently implemented on sow farms than in wean-to-harvest populations. At wean-to-harvest sites, practices remain inconsistent and less rigorously enforced, where gaps in practices like hand hygiene, disinfection, and supply decontamination persist. As a result, the risk of pathogen introduction is heightened, revealing the need for stronger adherence to biosecurity protocols across this stage of production.
These findings highlight the need for targeted biosecurity measures, especially in the finisher phase, where the risk of outbreaks is higher. Results underscore the importance of implementing effective biosecurity practices, such as regular washing, downtime, and preventing sick animal transport, to mitigate the risk of PRRSV transmission.
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