Beyond porcine circovirus associated disease, 2007 was a tough year for growing pigs and a great year for porcine reproductive and respiratory syndrome virus. Large numbers of PRRS-negative sow farms and PRRS-negative growing-pig populations broke with this disease.
The results were disastrous. Sow operations lost more than $100 per sow and wean/finish losses amounted to more than $10 per pig placed.
In looking back on the year, one has to ask: What factors can a pork producer control to help reduce the chance of his herd becoming infected with PRRS virus or another swine pathogen?
Let’s dig into that question.
Often we work very hard (and spend a lot of money) to produce PRRS-negative pigs from a sow farm. With that said, it is surprising to me how poor many operations are at implementing routine biosecurity measures to keep PRRS virus and other pathogens out of the growing-pig side of the operation. Many procedures that are routinely used at the sow farm work well in nursery, finishing and wean-to-finish barns.
So, let’s review some protocols to keep growing pigs disease-free.
Start by understanding the weaned pig’s true status. For this, many producers routinely use a weaned-pig audit. Under this scenario, 30 piglets are sampled monthly, using the PRRS
The test looks for virus in the piglets’ blood. Sample frequency can be adjusted based on sow-farm history. Getting three negative tests in a row is a good indicator that the farm is producing PRRS-negative pigs. If your pigs leave a nursery or a double-stocked wean-to-finish barn as feeder pigs and go to a finisher, it’s good to get a sample of 10 pigs to confirm their entry status and make sure the herd’s previous status has not changed.
Usually a PRRS Elisa test is run to determine if any antibodies were produced from PRRS-virus exposure. We often get a finishing-exit status of 10 pigs to check the true status as pigs are sold to market.
There’s been extensive testing and experimentation during the last several years showing the pig-hauling truck’s role in disease transmission. Here’s what we know:
A truck can get contaminated with PRRS virus from hauling infected pigs.
PRRS virus can remain on an improperly washed trailer.
Contaminated trailers can infect PRRS-negative pigs.
Cleaning, disinfecting and drying will kill PRRS virus. This is time consuming and expensive, and the results should be audited by swabbing the cleaned trailers.
Trucks can get re-contaminated, especially in cold, wet, freezing temperatures.
Understand who is allowed to go into the truck to move pigs out, and monitor the related procedures at truck entry.
Often the trailer is more biosecure by not going to a common truck wash, but by being routed to go from the sow farm to the nursery/wean-to-finishing stage and being washed on Friday, with downtime allowed during the weekend.
The chute is too often overlooked. Many times there is no physical covering placed over it, which leaves it exposed to freezing temperatures and makes it difficult to thoroughly wash and disinfect. Here are some options to address this:
Disinfect with a propylene glycol-based product if temperatures are below 32° F.
Apply lime, QuickDry or another type of drying agent within a washed loading chute to help the process.
Provide deep bedding within and around the chute.
Designate a “clean/dirty” line:
Establish a line that represents a transition from the outside world to the inside of a barn housing pigs. Foot traffic — in and out — of the barns is often a reason for contamination. Just imagine how much virus could be lying around from rendering trucks, feed trucks, garbage pick-up, service vehicles and people, as well as trucks headed for market in a pig-dense area. It’s critical that you establish a plan that stops outside pathogens from entering a pig barn. Here are some options:
Shower before entering a barn. This is an excellent way to distinguish a transition line from dirty to clean areas.
Sit on a bench to remove outside footwear; without allowing feet to touch the “dirty” side, swing legs over the bench and put on the barn boots. Wash your hands and put on barn coveralls.
Having barn-specific coveralls and boots will limit the spread of PRRS virus from barn to barn.
Follow those same procedures on your way out of the barn, and be sure to wash your hands with soap and water before leaving the barn.
Do not carry equipment such as sort boards, syringes or snares from barn to barn or site to site.
Dead pig removal:
What to do with dead pig carcasses can be tricky and easy to overlook from a biosecurity standpoint, but it’s important to pay attention to these areas as well. Here are some steps to take:
Designate a specific door through which you will remove dead pig carcasses.
No equipment should travel in and out of the barn — this could include a dead cart, snares and other related equipment.
Do not step outside as you remove the carcass from the building if you plan on returning to the barn.
After exiting the barn to remove the carcass from the area, take carcasses to a designated rendering pick-up area or the compost pile. Do this as the last task at the end of the day. At this point, do not re-enter the barn.
Composting vs. rendering:
The goal is to reduce the likelihood that something or someone will drag virus to the growing-pig site. A carcass-composting system will effectively reduce this risk. If composting is not an option, look closely at establishing a pick-up location for dead pigs.
The important thing is to get as much distance from the pick-up site and the barn as possible. Also, design it so there is no crossover traffic. This can be accomplished by designing the site so that dead pigs go in on one side of the storage facility and are picked up on the opposite side.
Having dead-animal pick-up at a completely separate and isolated location from your production site is the best option.
We do know that PRRS and other viruses will travel via air currents in the correct meteorological conditions. Some factors will remain outside of your control, but before you blame aerosol transmission, make sure that all other biosecurity protocols are in place.
Air filtration is now in place at many boar studs and some sow farms with positive results. It is an expensive option, but it needs to be tested on nursery and wean-to-finish facilities in 2008.
Site clean up:
The good news about most nursery, wean-to-finish and finishing sites is that today they are operated in line with all-in/all-out pig flows. It’s important that each time the building is turned over with pigs, it gets a thorough washing, disinfection and drying period -— and, let me emphasize, an inspection — before pigs are allowed back in.
In the end, with disease losses exceeding more than $10 per pig, it is worth the time and expense to review all of the biosecurity protocols that you have in place for your growing-pig system.