Practical measures to limit the spread of infectious diseases of pigs both within a farm and from one farm to others - is an essential part of risk management for pig producers.
Common infectious diseases of pigs such as enzootic pneumonia, pleuropneumonia, mange, and swine dysentery pose constant challenges to Australian pig producers. Millions of dollars are lost each year as a result of deaths and decreased growth and reproductive rates. Control measures such as vaccines, antibiotics and other chemicals further add to these costs. Minimising the level of disease within the herd can dramatically reduce these costs, with a resulting increase in profitability.
Biosecurity is the best form of defence against both endemic and exotic diseases. Eradication and recovery from an exotic disease outbreak will not only be costly, but the long-term prosperity of the Australian pig industry could be damaged if a foreign disease became established. International market access for pork products is increasingly dependent on demonstration of the absence of certain diseases from Australia.
A good biosecurity program limits the movement of infectious diseases of pigs from one property to another and from one unit within a property to another.
Infectious agents can be spread by pig to pig contact, illegal importation and disposal of contaminated meat products, semen, aerosol, contamination of people, their clothing and equipment. Veterinary equipment, transport vehicles, contaminated feed and water, biting insects and wildlife vectors are all important methods by which infectious agents can be moved from property to property and pig to pig.
Feeding food scraps (also known as swill or prohibited pig feed) to pigs is illegal in Australia as it is the most likely way that Australian livestock may be exposed to an exotic disease agent. Exotic diseases that can be spread by feeding swill to pigs include foot and mouth disease (FMD), classical swine fever, African swine fever and swine vesicular disease. Legislation has been in place for many years in Australia to prohibit swill feeding (PDF, 191.64 KB).
In order to limit the risk of aerosol disease spread (tiny particles or droplets in the air), a minimum buffer distance between neighbouring pig farms and between units within a piggery is desirable. Aerosol spread is just one of the many ways a disease could enter a piggery. The level of risk is also dependent on the diseases present, the level of infection in the herd, stocking intensity, the topography of the property and direction of the wind. As a guideline, a minimum biosecurity buffer distance of 3 km between sites is recommended, but should not be interpreted too prescriptively as effective biosecurity is achieved through a combination of measures.
Most diseases are introduced to a pig property with the arrival of new pigs. Introduced pigs present the greatest risk of introducing new diseases to a herd as the most likely spread of disease is from pig to pig. Pig producers are therefore encouraged to buy replacement animals directly from a single herd of a higher or comparable health status. Contact your local veterinarian for advice. An alternative is to maintain a closed herd and introduce new genetic material by the use of artificial insemination. Semen should only be purchased from an approved centre of known health status.
All new stock should be inspected by trained staff upon arrival and regularly thereafter. Introduced breeding stock should be kept separately (quarantined) from the main herd, ideally for 6 – 8 weeks. The quarantine facility should be situated at least 3 km and ideally 5 km from the home farm. Separate boots and overalls should be provided for use at this site and hands should be washed after handling quarantined pigs. While a quarantine facility may be appropriate for herds introducing breeding stock it is impractical for farms that regularly introduce growing pigs as part of multi-site operations. In well-run operations, an all-in, all-out system should ensure a degree of isolation for each batch, and assist containment of introduced diseases. Buildings should be thoroughly cleaned and disinfected between batches.
Where appropriate, a secure pig proof fence should be erected around the piggery to prevent access of feral pigs and other animals. Strict measures should also be in place to ensure that all gates are kept closed when not in immediate use.
Sheep, cattle and goats grazing between piggery buildings normally pose little risk, provided that they do not move between properties, their manure does not come in contact with pigs, and they are not grazed around feed silos nor allowed to eat pellets that contain meat meal. However in the case of an FMD outbreak in a piggery they would pose a significant threat.
Pest and insect control programs should be in place. A plentiful supply of dead carcasses and spilt feed will encourage the expansion of bird and rodent populations. Appropriate hygiene and carcass disposal procedures are an essential component of any pest and insect control program. Flying foxes (fruit bats) have been implicated in the spread of Menangle virus in Australia and Nipah virus in Malaysia. If necessary, bird netting and habitat reduction can be used to limit the access of flying foxes to the pig herd.
Only prescheduled visitor's essential to the farm's business should be permitted entry. Conduct a risk assessment before allowing visitors into the farm area of the property. It should take into consideration things such as recent travel overseas, contact with other pigs and livestock and health, for example influenza like illnesses. All visitors should enter via a single point where they sign a Visitors' Book and are issued with protective boots and clothes. This clothing should be used in the piggery only. Clearly demarcated "clean" and "dirty" areas should be established to ensure there is no confusion about where people need to remove their off farm "dirty" clothes and footwear, put on "clean" farm boots and clothing and wash their hands. Signs, locked doors and locked gates can be used to discourage pig and feed truck drivers, or other unauthorised visitors, from entering sheds.
All staff should be aware of the risks entailed in off site contact with other pigs. Staff should not keep their own pigs unless this is cleared with management first. Rules for staff entry should be similar to the rules for visitors, except that staff need not be required to sign the visitor movement record. Staff should not wear "dirty" clothing in "clean" areas. Staff movements between units within a piggery should be planned, especially if more than one age group is housed on one site. Staff should move from younger to older pigs through the day. Hands should be washed between units or rooms and after handling sick pigs, which should be visited last. Contaminated clothing should be changed between units.
Wherever possible a load out site at the farm perimeter should be used. Load out areas present a risk if a pig transport vehicle arrives on farm dirty or carrying pigs. This should not be allowed to occur unless the pigs on the truck have the same health status as your own pigs. There is a risk from aerosols and from movement of pigs onto the truck and then back to the farm by mistake. This risk can be reduced by providing a "dirty" loading area that is separated from the "clean" farm areas, with a "no return" policy, "no return" gates, and appropriate signage. All vehicles transporting pigs should be cleaned and disinfected before pigs are loaded.
The farm's biosecurity program must provide for mandatory cleaning and disinfection of any equipment (such as snares or ultrasound pregnancy detection equipment) that is moved by consultants from farm to farm. Syringes used for injection or needles used for blood collection should remain on farm and be destroyed after single use. Post mortem implements used by veterinarians for sample collection should remain off farm or be used in areas that are not in direct contact with the herd.
Disposal of piggery effluent, dead pigs and other biological material should be by approved methods.
Records should be kept of the movements of animals, people and vehicles onto and off the farm to assist tracing in the event of an emergency disease outbreak. This information is vital to ensure that the disease is rapidly and effectively tracked and contained.
Staff should be trained to recognise signs of disease in the herd and to report any unusual signs or explained deaths promptly. Mortality and disease records should be kept. If something unusual or unexpected happens and infectious disease is suspected, veterinary advice should be sought as soon as possible. Rapid recognition of abnormal disease patterns is extremely important and will lead to prompt diagnosis and efficient management of any emergency disease. NSW DPI conducts exclusion testing for notifiable pests and animal diseases.
All pig owners in NSW must apply for a property identification number (PIC) that identifies the property of birth or the place where pigs are kept. All properties that sell pigs must have a tattoo brand and/or ear tag that link to the PIC identifying the property at which a pig was kept before the application of the tag or tattoo. Producers who cease to keep pigs on their property are required to notify the Secretary and return any unused tags or pig tattoo branding equipment.
Identification of pigs going for sale or slaughter is an essential part of monitoring for diseases and chemical residues. All pigs consigned for sale at a saleyard, slaughter at an abattoir or disposal at a knackery must be identified by either a tattoo brand or ear tag prior to leaving their property of origin. The tattoo or tag must identify the property on which the pigs have been kept immediately before dispatch. Pigs over 25 kg body weight must be tattooed and pigs below this weight must be ear tagged.
All pigs dispatched from a property to another property, to a saleyard or to an abattoir must be accompanied by a correctly completed national vendor declaration, such as PigPASS NVD, except for movement to another property, where the ownership remains unchanged and the property of dispatch can be identified for the life of the pig.
For more information regarding responsible pig ownership ().