Christensen Family Farms (CFF), Sleepy Eye, MN, tightened up biosecurity to limit porcine reproductive and respiratory syndrome (PRRS) — and it has reduced breaks.

As many hog farms have learned, cleaning up PRRS is the easy part. Preventing the next break presents a much tougher challenge.

CFF has had a biosecurity program in place for many years, which effectively kept out most new diseases — but it didn't keep out the PRRS virus, says Joel Nerem, CFF staff veterinarian.

CFF presents a tough biosecurity challenge with 150,000 sows across five states. Company-owned gilt and sow production has been conventional health status, with PRRS-positive gilts sourcing new PRRS virus into sow farms. Pigs flow to company and contracted nursery and finishing barns.

To keep PRRS out, CFF designed a long-term disease prevention plan based on an aggressively enforced biosecurity program aimed at reducing disease spread between farms, Nerem reports at the George Young Swine Conference, South Sioux City, NE.

The effort has reduced the number and severity of PRRS breaks and has kept out other diseases.

Biosecurity Program Principles

CFF's new biosecurity program:

  • Keep it simple and consistent;

  • Define biosecurity as procedures to keep out new diseases;

  • Consider every farm “clean” to diseases it does not have, therefore, a new disease/strain introduction to a conventional farm can be just as damaging to health and performance as to a high-health farm. Apply biosecurity principles equally to all farms.

  • Realize the vast majority of potential disease breaks are within CFF's control. “The fact is, we are our own worst enemy when it comes to dragging bugs onto our farms,” says Nerem.

  • Set up a recognized barrier to protect the farm's pigs from exposure to contamination by outside disease agents. “In our system, this barrier is called the ‘clean/dirty line.’ In order for anything to move from the dirty to the clean side, it must either be ‘decontaminated,’ or proven to be free of disease contamination,” says Nerem.

Managing Risks

To address specific risks, CFF focuses on three areas for surveillance: replacement breeding stock, boars (semen) and sow farms.

Two types of monitoring are used.

Reactive monitoring measures disease signs such as coughing. Sudden deaths result in immediate site quarantine, submission of diagnostic materials and veterinary followup.

Reactive monitoring is used to identify diseases that can't be monitored serologically because of vaccination status (Mycoplasmal pneumonia, swine flu) or for diseases that can produce pronounced clinical signs (Transmissible gastroenteritis, Actinobacillus pleuropneumonia).

Proactive monitoring is applied to PRRS serology and molecular diagnostics.

CFF's PRRS protocol is to test replacement stock prior to movement, boars prior to semen shipment. Results decide if animals or semen are shipped.

“Any results that do not meet expectations — positive or suspicious — result in quarantining and retesting,” states Nerem.

Pig transportation has been shown to be a key biosecurity risk, and very effective way to spread PRRS virus, based on recent research. To control truck risk areas CFF has:

  • Established dedicated trucks, trailers and drivers for PRRS-positive or PRRS-negative loads. Those vehicles use dedicated truck washes that are positive or negative for PRRS.

  • Assigned dedicated trailers to specific farms, flows or pyramids within the PRRS-negative system. Pigs from a farm with greater potential for disease introduction are hauled on separate trailers from trailers moving replacement stock into a multiplier.

  • Started a strict truck sanitation program. “All trailers dedicated to our PRRS-negative wash/flows are washed, disinfected with a tested disinfectant product, dried and individually inspected,” comments Nerem. “Trailers that don't pass inspection are rewashed and must pass inspection before hauling pigs.”

A second transportation risk is loading areas, which must be washed and disinfected if open to the outside. Pig movement must be unidirectional and all parties must recognize the “point of no return” (clean/dirty line).

The third transport risk area is disease exposure from in-transit contamination due to aerosol spread and road spray. Dedicated truck routes and off-hour deliveries are followed to reduce pig exposure in transit.

Restricting Access

On-farm access is restricted by:

  • Eliminating rendering for dead disposal on sites of high biosecurity importance.

  • Keeping gates to the sites locked and only individuals approved for site access have keys.

  • Notifying employees weekly on the correct order to access sites, from a biosecurity standpoint.

  • Enforcing downtime rules.

To move from the dirty side to the clean side requires:

  • People: Follow the shower-in, shower-out process. Entry requires farm manager approval.

  • Pigs: Incoming animals require quarantine, observation and blood testing to prove they are not bringing in disease.

  • All supplies and other items brought onto the farm must be disinfected, fumigated and a minimum downtime observed.

  • Exceptional items like semen, lunches and certain electronics are double-bagged and handed through the window, which is the clean/dirty line. Double-bagging is a process where items in a “clean” environment are placed within two plastic bags, each individually sealed and delivered to the farm. At the farm, the person delivering the item opens the outer bag, and someone on the clean side retrieves it through the window, grasping the inner “clean” bag and transferring the item into the clean side of the farm.

  • Restrict access by insects, rodents and other pests. Insect netting is placed on inlets and the sidewalls of naturally ventilated barns. Insecticides and rodenticides are used regularly, along with environmental management, to eliminate insect and pest habitats.