Air Filtration

Preventing the spread of PRRSV within and among pig populations is a priority on pig farms. Pigs may become infected via exposure to PRRSV by any of several routes, including saliva, nasal secretions, urine, faeces, intramuscular injections, vaginal, mammary gland secretions, semen, fomites (boots, coolers, shipping parcels, and vehicles), transport trucks, and aerosol. To reduce the risk of spreading PRRSV by aerosol, some pork producers have installed air filtration systems on their buildings such as boar studs, sow facilities, and growing-finishing buildings. Factors that influence whether an air filtration system is installed depend upon the individual producer’s budget, the location of the site (high pig density vs. low pig density), the level of acceptable risk, and the type of production system (breeding stock or commercial).

Filters have been installed either in the attic through the insertion of filters into the ceiling inlets or in the form of a filter bank preceding the cool cell pad. If an air filtration system is installed in a building, all areas of the barn that could serve as potential air leaks need to be sealed. This includes cracks in the building and around windows and doors, shutters, and idle fans. In addition, double-door entry or exit systems must be installed to prevent potentially contaminated air from entering the animal air space at high-risk points, such as personnel entryways, live or dead animal load-out rooms, delivery and disinfection rooms, and so forth. In addition to contacting a swine veterinarian and an agricultural engineer with experience in the design and management of an air filtration system for pig facilities, the following references discuss various aspects of air filtration systems: Dee et al. (2010), Groth (2008), Jordhal (2010), Mohr (2010), Pitkin et al., and Reicks (2006, 2008, 2009).

Equipment and Consumable Suppliers

All equipment and consumable supplies brought into the pig operation should arrive clean and undamaged. Many farms bring supplies through a fumigation room or spray them with disinfectant at the entry point. The greatest risk that accompanies consumables is that they may have been delivered to another farm, returned, and then redistributed by the supply company. Likewise, the delivery driver poses a significant risk if other pig farms are on the delivery route. It is wise to discuss this with the local delivery carrier. Possessing a proper location and facility where items enter the farm helps ensure biosecurity compliance. The physical structure to receive items entering the farm should be located on the fence perimeter (dirty side). A door allows access to the outside. All new equipment or consumable supplies are delivered to this structure. Consumable supplies (such as pharmaceutical products, heat lamps or light bulbs, artificial insemination supply containers, and so forth) should be disinfected by hand. If possible, all of the new equipment (such as sort boards, pen partitions, wrenches, hammers, and so forth) should be put in a solution of disinfectant. Some operations use fogging or fumigation devices to disinfect items. However, fogging does not always reach the entire area of the bottom of items unless the items are placed on woven wire shelves. In small operations, it may be best to deliver all consumables to the owner’s home where they can be inspected and disinfected prior to moving them into the pig facilities.

Many times, equipment and supplies brought into the pig operation by contract people providing a service to the unit are not new, and, in many cases, these tools frequently are used on other farms. Therefore, it should be mandatory that the service person’s equipment and supplies be thoroughly cleaned before coming to the farm, and these tools pass through a disinfection room. It is a good idea for the farm to have some of the general tools needed by service personnel. Ideally, equipment used on another pig operation by a consultant or adviser (such as an ultrasound device or individual pig scale) should not be allowed into the pig operation.

Biosecurity procedures also need to be established for the following items used in the pig operation: notebooks, paper, pencils and pens, laptop computers, mobile telephones, wristwatches, cameras, and so forth. These items should be farm-dedicated equipment and supplies. In addition, the office and workers’ accommodations should be kept clean and uncluttered.

Farm Machinery and Equipment

Farm machinery and equipment can be a risk for transmitting disease to a pig operation, especially if the machinery and equipment were used outside of the pig operation.

The following procedures will help prevent disease transmission:

Avoid borrowing equipment (especially manure handling equipment) and vehicles from other farms.
Avoid bringing farm machinery or equipment to the pig unit unless it is essential.
Any equipment brought into the unit must be thoroughly cleaned and disinfected prior to entry. This procedure especially includes machinery used for manure and/or slurry handling.

Bedding Material

Store bedding so it is protected from the weather. Ideally, bedding storage also should prevent contamination by vermin.
Straw should come from a source that has not exposed the straw to livestock. Purchase bedding material from suppliers that have dedicated trucks and/or trailers that only haul bedding.

Hygiene and Sanitation of Buildings

Litter should be promptly and correctly removed from the pig unit. If a garbage pickup service is used, the rubbish containers should be placed outside the clean and dirty perimeter as far from the pigs as feasible.
Buildings, barns, equipment, clothing, and footwear that pigs come in contact with should be routinely cleaned and disinfected. Disinfection should be accomplished only after thorough cleaning. Cold temperatures and organic material reduce the effectiveness of all disinfectants. The chemical agents commonly used require several minutes of contact with disease-producing agents to be effective.

Cleaning and disinfection procedures should include:

Removal of all bedding, manure, and feed. These items contain a high level of contamination and interfere with effective cleaning and disinfection.
Thorough cleaning of the under-surfaces of equipment. If possible, removable equipment should be taken out and cleaned separately.
Turn over feeders after the inner surfaces are cleaned so all water drains from them, and the floor can be sanitised.
Thorough cleaning with hot, soapy water, preferably through a pressure wash.
Rinsing with clear water to remove all residues.
Correct application of an approved disinfectant to everything pigs come in contact with, including the under-surfaces of equipment.
An adequate drying period for the area before the introduction of new animals. Consult a veterinarian for specific recommendations pertaining to the situation.
Many infectious agents survive in wet, dark places. Sunlight and drying will destroy many bacteria and viruses, but not all.
Some infectious agents will survive in faeces and mucus on boots and clothing so clothing and footwear should be routinely laundered or cleaned.
Clean and disinfect any equipment that has been used on sick animals prior to use on healthy herd mates.
PPE is specialised clothing worn by an employee for protection against hazardous materials as mentioned above and should be worn.

A. Boot Baths

Boot baths are practically useless in eliminating bacterial contamination. To provide any protection, boots must be free of organic matter and spend more than five minutes in the disinfectant solution. Some pig farm personnel do use boot baths in an attempt to prevent mechanical transmission of pathogens among groups of pigs. However, maintenance of boot baths in most facilities is poor. Most boot baths are grossly contaminated with organic matter (faecal material). Workers commonly avoid stepping into the boot baths, or quickly step through the boot bath without stopping to clean their boots. Two studies at Purdue University (Amass et al., 2000 and 2001) have shown that simply stepping through or standing in a boot bath without first removing all visible organic debris from boots does not provide effective boot disinfection. Virkon®S is a suitable disinfectant for use in boot baths when used appropriately.

A suggested procedure is:

Make sure the boots do not leak.
Have a clean or dirty demarcation at each boot bath site.
Use a boot bath that contains 1 percent Virkon® S.
Have the people wash the organic material off their boots with a water hose and brush prior to stepping into the boot bath. This allows the disinfectant to be changed less frequently and costs less.
Step in the boot bath for a few seconds (count to 10).

Proper disinfection has been accomplished after manure-free boots were soaked in Roccal®-D Plus for five minutes. But, removing all visible manure from boots and then soaking boots in a clean disinfectant boot bath for at least five minutes is not practical on most farms. The use of a “soaking boots bath” might be an option in areas containing valuable breeding stock or sick animals. A soaking boots station could contain a wash area for scrubbing and cleaning off manure and a disinfectant soaking bath containing spare boots. Workers remove contaminated boots, clean the boots, place them in the tub of disinfectant, and put on the spare boots that had been soaking in the disinfectant.

An alternative to the boot bath is:

Boots worn outdoors are removed at the entry door for the pig facility. Some farms have a bench for workers to sit on while removing their boots. The workers swing their legs over the bench to put on indoor footwear. The area under the bench is enclosed to prevent dirt from entering the building.
Outdoor boots are stored outdoors.
Boots to be worn indoors are immediately available inside the door.
Indoor walkways are cleaned daily.
Boots worn indoors are washed at the end of each day in a location that has a large drain, detergent, scrub brush, disinfectant, a pressurised water spray, and a boot drying rack.
Boots worn outdoors are washed, disinfected, placed on a drying rack, and kept in an appropriate storage area away from the pig facilities at the end of each day. The storage area used for boots worn outdoors may need to be heated during the winter months.

Dead Pig Postmortem and Disposal

Pork producers need to seriously consider developing a plan to deal with postmortem examinations and disposal of dead pigs. If a postmortem will be performed on the farm, an area outside of the farm perimeter should be established. This procedure allows a veterinarian who may not have been away from pigs to perform the postmortem examination.

The method used for the disposal of dead pigs and afterbirth can create a biosecurity hazard. Dead pigs and afterbirth must be disposed of in a manner to prevents the attraction of wild animals, birds, and insects. Excreted body fluids must be cleaned up, and the area cleaned and disinfected. Because states are continuing to modify their environmental regulations and the availability of rendering services continues to shrink, pork producers need to contact the appropriate state agency (agricultural and/or environmental) to determine what methods can be used to routinely dispose of dead animals and afterbirth. The methods include burial, rendering, composting, and incineration. When a pig dies, it needs to be disposed of in a prompt and correct manner.

The collection point and associated equipment used to transport dead animals to the collection point need to be cleaned and disinfected after every use. If cleaning is done by farm workers, cleaning should be done at the end of the day, so workers do not need to re-enter the farm or buildings that day.

The advantages and disadvantages of various swine mortality disposal methods.

Method	Advantage	Disadvantage
Burial	Prompt burial gets dead stock out of public view.	Poor or delayed coverage can result in odour, flies, and scavengers.
	Prompt burial coverage prevents odour, flies, and scavengers.	Burial pits can collect rainwater.
		Burial potentially results in pollutants going into the soil. Thus, environmentally sensitive locations are not acceptable for burial.
		Burial pits can be difficult to dig in the winter.
Rendering	Rendering converts animal mortality into useful byproducts.	Some pork producers do not have access to a rendering plant.
	Prompt transport to rendering plants removes dead stock from the farm.	Some rendering plants charge fees for accepting carcasses.
	The collection area for dead animals is located away from the pig unit.	Vehicles and personnel travelling to and from the farm and rendering plant can compromise biosecurity.
		Storage of dead hogs in “dead boxes” or other methods prior to being picked up by the rendering truck can cause odour and attract flies and scavengers unless refrigerated.
		Rendering trucks are a serious risk for a breakdown in biosecurity. There should be a clear demarcation between the farm access and the collection service access. Ideally, the rendering vehicle should not be allowed to come closer than 2 km from the pig unit. Contact with the driver and farm personnel should always
Composting	Proper composting generates minimal odour, fly, or scavenger problems.	A readily available supply of carbon-rich bulking materials such as sawdust, ground cornstalks, or other suitable materials is required.
	Prompt composting gets dead stock out of public view.	Some initial capital costs are necessary for the construction of composting facilities.
	Proper composting has low potential for pollution and produces a final product that can improve soil tilth and fertility.	Poorly maintained compost units (with inadequate bulking material, delayed carcass coverage, and so forth) will result in odours and attract flies and scavengers.
Incineration	Prompt incineration gets dead stock out of public view.	Older, less efficient incinerators may generate smoke and odour. Many environmental agencies are reluctant to permit burning of carcasses because of serious problems with air pollution.
Incineration	Modern incinerators reduce carcasses to ash and are biosecure.	Modern incinerators have large capital costs and fuel requirements of 7 litres per hour.

Wild Mammals, Birds, Parasites, and Pets

Preventing birds, rodents, pets, and other animals from coming in contact with the pigs will be impossible when housing the herd outdoors. However, you can do some things to make the farm less desirable to these creatures. Examples include keeping the unit clean and tidy by controlling the vegetation or weed growth within and surrounding the pig area; immediately cleaning up spilled feed; discarding rubbish and debris in a timely manner; and promptly removing dead animals. The insect population can be lessened by spraying and eliminating areas with standing water.

A. Rodents

Rodents can transmit swine diseases such as leptospirosis, trichinosis, toxoplasmosis, erysipelas, swine dysentery, and others. Mice and rats can spread diseases from contaminated areas to uncontaminated areas via their droppings, feet, fur, urine, saliva, or blood. For example, mice may walk through infected manure and then contaminate the food and water of healthy animals several hundred feet away or take a disease to nearby uninfected barns. A large rodent population represents a significant amount of feed wastage. One rat can eat 250 grams of feed per week and contaminate about 10 times the volume of feed eaten. Rats often travel long distances and are a significant bio-exclusion and bio-containment risk. Rodents also may chew the insulation off wires, causing a fire hazard. Biosecurity cannot be assured if rodents are tolerated in or around swine facilities. All pig farms should have an active rodent control and monitoring system in place. To control rodents, identify and routinely bait places where rodents could potentially den in storage areas or barns.

Inspect buildings and feed storage areas for evidence of rodents, such as droppings and nests.
Identify their source of food and prevent their access to it.
Destroy their denning places and block off any small holes to prevent them from re-entering.
Eliminate hiding areas around barns and storage facilities. Consider installing a 3-metre-wide area of 2 cm rock around buildings and removing all vegetation close to building entrances. Rodents do not like crossing wide-open areas.
Use traps or bait stations placed 3 to 6 m apart to catch rodents.
Use tamper-resistant bait stations to protect farm pets, especially dogs, from rodent poison.
Search for dead rodents and dispose of them appropriately. Do not touch them with bare hands.
Prevent more rodents from coming onto the farm by maintaining a clean and regularly inspected facility.

B. Predators and Scavenger Animals

Predator animals that might need to be controlled on the pig farm are wild stray dogs, and jackals. Jackal are wild canines with dog-like features. They are well-adapted to populated areas and are not strangers to farms, fields, and woods. Jackal are less likely to attack livestock where wild game such as rabbits, and mice are plentiful. How dead livestock are handled may enhance a farm’s predator population and encourage predatory attacks on swine housed outdoors. Predators may carry disease-causing agents (leptospirosis and others) so they should be kept out of areas where swine are pastured or housed.

C. Feral and Wild Pigs

Feral swine are defined as free-roaming animals that are not being held under domestic management or confinement. Feral pigs come from several sources and include released or escaped domestic swine and the truly wild European boar. When free-roaming in the term “feral swine,” as are hybrids of the two types. Although morphologically distinct, both the feral swine and European wild swine are recognised as Sus scrofa. Feral swine are highly mobile disease reservoirs and can carry at least 30 important viral and bacterial diseases in addition to a minimum of 37 parasites that can affect people, pets, livestock, and wildlife. Feral swine carry brucellosis and pseudorabies. Feral swine is one of the greatest risks to domestic swine because the reintroduction of either of these diseases will lead to farm depopulation.

D. Birds

House sparrows, starlings, pigeons, and swallows commonly inhabit animal housing on livestock farms. Large numbers of birds in and around swine facilities can cause damage and unsanitary working conditions. Because birds consume and contaminate feed and water, they can potentially transmit diseases to swine. Birds are known to mechanically transmit transmissible gastroenteritis (TGE) virus to pigs, especially pigs housed outdoors. Avian tuberculosis is frequently transmitted to outdoor pigs. Infected slaughter pigs are condemned, causing the packer and producer significant economic losses. Not only can birds spread disease onto healthy farms, but they also can be an expensive nuisance. A starling will eat 50 percent of its body weight in grain each day. Nests that are made in barns close to the heat of a light fixture or faulty wiring can be a fire hazard. Accumulated bird droppings can corrode equipment. The insulation of a building can be destroyed by birds. Before beginning a bird control programme, you should be familiar with the laws protecting birds. The nature of a particular bird species determines which methods to use for controlling problems the birds cause. To reduce the exposure of pigs to birds and their droppings, first evaluate the current presence of birds on the farm.

Identify the species of birds contributing to the problem.
Identify places on the farm where birds like to nest, bathe, and perch.
Inspect the farm for places where there are lots of bird droppings.
Observe whether birds perch on or above the pigs.
Observe whether birds bathe in pig water troughs.
The following are options for detracting birds. However, use of these methods is no guarantee that all birds will stay off the farmstead.
Install bird screening to prevent birds from accessing barns.
Ensure lids are kept on feeders and bulk bins.
If needed, clean out water troughs and feed troughs daily.
If pigs are housed outdoors, keep them away from ponds where birds congregate.
Destroy nests and eggs of nuisance birds.
Thin stands of trees where starlings roost.
Promptly clean up the spilled feed.
Discourage migrating flocks of birds from stopping at your farm.
Play recordings of distress calls.
Blow whistles that make an irritating sound.
Use visual detractors.
Install reflectors.
Attract raptors like red-tailed hawks.
Parasites (flies, mites, mosquitoes, lice, ticks, worms). All pig farms should control internal and external parasites. All incoming replacement pigs, unless specifically free, should receive two treatments, two weeks apart, with external and internal parasiticides. Faecal samples should be monitored from each production area on a quarterly basis to determine the presence of internal parasites. Further refinement of the deworming programme is based on the results of these examinations. An effective fly and mosquito control programme should be implemented. Mosquitoes and mite bites can reduce carcass value due to trim loss at slaughter.

E. Dogs and Cats (Pets or Feral)

Dogs can transmit leptospirosis but are most often a biosecurity risk if they travel to different farms. Toxoplasma ondii is a protozoan (single-celled) parasite found in muscle and other tissues of many warm-blooded animals, including pigs and people. Cats and other felids are the only hosts in which the parasite can complete its entire life cycle, and the only animals that excrete the environmentally resistant and infectious stage called the oocyst (“eggs”) in the faeces. Cats may shed more than 10 million oocysts per day for 3 to 10 days after infection. Pigs become infected when they accidentally ingest oocysts in soil or water or eat tissues of rodents, wildlife, or meat-containing cysts. Because it takes only one oocyst to infect a pig, the protection of pigs from environmental contamination, contamination of feed, and transport of oocysts on boots is vital to control. Risk analysis of management factors associated with positive pigs showed that infection correlated with the presence of infected juvenile cats (sources of oocysts) and T. gondii-infected mice.