Biosecurity on wean-to-harvest sites is inconsistent across the U.S. pork industry and a comprehensive study affirms it. In a study led by Gustavo Silva at Iowa State University, 47.3% of employees on the 3,680 sites surveyed said they visit more than one site daily and 57.6% of those sites require employees to shower in.
Researchers evaluated current bioexclusion practices among a diverse group of U.S. pork producers, the Swine Health Information Center (SHIC) reports. A questionnaire asked 69 questions on bioexclusion practices that covered site characteristics, vehicle movements, people movement, manure removal, water entry and sanitation. A weighted method ensured the results reflected all respondents’ answers.
In this survey representing 15.7 million pigs across 3,680 sites in 13 states, 10.3% were nurseries, 52.9% were finishing sites and 36.8% were wean-to-harvest sites.
- 93.3% reported using all-in-all-out
- 65.3% had mortality disposal off-site
- 47.3% of all employees visited more than one site daily
- 63.8% have shower facilities
- 57.6% require employees to shower in
- 56.9% require employees to shower out
- Manure is removed about 1.5 times per year, often by third-party companies.
- 87.7% rely on well water with 64.7% not performing any water treatment
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, SHIC reports.
As part of the project, researchers developed a biosecurity assessment tool. To do this, researchers enrolled 139 wean-to-harvest sites to assess biosecurity practices and their relationship with lateral introduction of porcine reproductive and respiratory syndrome (PRRSV), porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), and transmissible gastroenteritis virus (TGEV). Farms were required to be stable or negative for PRRSV and key enteric viruses, including PEDV, PDCoV, and TGEV, to participate.
In this survey representing 139 sites across nine companies in six states, there were 44 nurseries from three companies, 44 finishers from three companies, and 51 grow-finish sites.
- 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%).
- Nursery sites had 92% lower odds of reporting a PRRSV outbreak than finishers.
- 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,” SHIC wrote.
The study 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,” the study shows.
Researchers say more data is needed to refine biosecurity recommendations and help producers improve their practices, enhance surveillance, and build a more resilient industry.
“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,” the research shows. “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.”
SHIC says 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.
Editor’s Note: This study was 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.
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