Biosecurity at the poultry farm: a basic tool to ensure poultry health and welfare

Why is biosecurity important?

Nowadays, it seems obvious to insist on the importance of biosecurity, but it is essential that all actors involved in the egg and poultry sector are sufficiently aware and know the reasons why it must be rigorously applied:

• Economic reasons: pathogens affect the health, welfare, and technical performance of poultry.
• Public health reasons: eggs and poultry meat must be guaranteed to be safe for human consumption.
• Legal reasons: to ensure compliance with mandatory national, regional and/or local regulations

The identification of potential pathways for the introduction of a disease is the first step that should enable those involved to perform a risk assessment and then implement an appropriate biosecurity program. The main pathways for the spread of pathogens are:

• Airborne transmission
• Transmission by contaminated feed or drinking water
• Transmission by contact:
  • Direct contact: between birds in close contact
  • Indirect contact: through equipment, material, and vehicles or by live vectors, such as animals (wild birds, other livestock, pets, rodents, insects...) and people (farm workers, maintenance personnel, visitors...).

Structural biosecurity

This concept encompasses all aspects related to facilities and equipment. Poultry farms should be designed to facilitate biosecurity to limit access of unauthorized persons to poultry production areas and to prevent access by other animals, both domestic and wild.

Among the key aspects to consider are the following:

• All construction materials should be chosen to allow for effective cleaning and disinfection.
• Perimeter fencing with a single access gate that will always be kept closed and with "no trespassing" signs, except for authorized personnel.
• Fumigation station for vehicles entering the farm, preferably an automatically activated disinfection arch, including a disinfection basin. Only essential traffic should have access to the farm. Other vehicles should be parked outside the biosecurity zone. Ideally, feed storage silos should be located close to the perimeter fence so that they can be filled from the outside and reduce the risks associated with feed transport trucks.
• Sheds should have a 1 to 2 m wide strip of concrete, gravel or neatly cut grass around the perimeter, and this area should always be kept free of waste material, weeds, garbage, or unused equipment. Maintaining this area near the house in good condition will reduce potential hiding places for vermin or nesting areas for wild birds and help reduce the presence of rodents around the houses (Image 1).
• Poultry houses must be constructed to prevent access by birds and rodents, and all possible entrances must be completely sealed or covered with chicken wire. It is essential to periodically check and ensure good maintenance of any areas of the house that allow animals to enter, paying special attention to risk areas such as air inlets, extractors, egg conveyors, litter pits, drains, etc.
• Maintenance of an adequate drainage system to avoid the accumulation of water that could attract migratory birds.

Operational biosecurity

This concept would include all those operations that are routinely performed on a farm on a regular basis, such as personnel entry, vehicle entry and disinfection, pest control, waste disposal, etc. These routine operations must be clearly described in the corresponding farm operating procedures manual.

• All farm waste must be disposed of safely. Whatever the method of disposal (incineration, composting, removal by specialized waste management companies), it should comply with the environmental requirements of the local regulations in force. Preferably, dead birds should be stored in freezers or water-, rodent- and wildlife-proof containers until removal or disposal.
• The drinking water for the birds, as well as the water used in the possible cooling systems used in the houses (foggers, evaporative panels...), must be of good sanitary quality. It is recommended to have an efficient water treatment system in place to ensure that adequate standards are met. Water tanks should always be kept closed to avoid attracting wild birds, as they represent a high risk of contamination by undesirable microorganisms.
• Pathogens can also be transmitted through feed, either by contaminated raw materials, by cross-contamination after the compound feed is produced or during transport. Feed mills should always follow good manufacturing practices. There are different types of treatments (chemical or thermal) to minimize the risk of introducing a disease through the feed. To avoid on-farm contamination of feed by rodents or wild birds, silos should always be kept closed and any feed spillage should be cleaned up immediately.
• It is essential to design a control program for rodents, wild birds, and other pests, particularly flies, mites and darkling beetles (Alphitobius). Bait stations should be installed along the walls of the houses and in any area where high rodent activity is observed. Stations should be checked weekly and fresh bait replenished as needed. It is important to keep a detailed record of the location of each bait station, its level of utilization after each check, the chemicals used and the frequency of bait replenishment.
• Moving or exchanging equipment between facilities is often a major pathway for the introduction or spread of disease: each farm should be self-sufficient in terms of mobile equipment (e.g., scales for weighing birds). If exchange of equipment or material between houses is unavoidable, it should always be thoroughly cleaned and disinfected before entering the house. Only equipment necessary for normal operations should be kept in the storage room, and always keep them tidy to minimize potential hiding places and places attractive to rodent breeding.

Staff and visitors

Special mention should be made of people entering the farm, since they are the most common animate factor involved in disease transmission: this includes farm employees, veterinarians, truck drivers, intervention teams (vaccination, beak treatment, loading and unloading of birds), external workers in charge of repairs and maintenance, etc. Visits should be kept to a minimum, only if strictly necessary, and all unauthorized persons are expressly excluded.

• The farm (ideally each house) must have a single access and be equipped with a properly designed changing room following the concept of "dirty zone" and "clean zone": a physical barrier must clearly delimit the separation between both zones (Image 2).
  • The dirty area should be equipped with a clothes rack for clothes used outside the farm, preferably showers or, at least, a sink with bactericidal soap to sanitize hands.
  • The clean area should have a closet with clean clothing (coveralls and disposable caps or head coverings) and clean footwear, all for exclusive use on the farm, as well as a footbath with disinfectant.
• Poorly managed footbaths can become a source of contamination: they should be cleaned daily and replenished with fresh disinfectant: disinfectant products can lose activity due to the action of sunlight, being diluted by rainwater or becoming soiled with mud or organic material. The soles of the shoes are also a place with ideal conditions for the multiplication of pathogens: it is important to brush the soles before going through the footbath and to clean and brush them after each visit (Image 3).
• Farm personnel should not have contact with other poultry or wild birds and should strictly comply with the established rules regarding the use of clothing and footwear for exclusive use in the clean area. It is particularly important to wash and disinfect hands before starting daily work, after each break (e.g., for lunch) and especially after using the toilets and whenever hands are not clean.
• Hands, hair, and clothing can become contaminated with dust containing microorganisms responsible for the spread of diseases from one farm to another. The sequence of visiting different flocks should always start with the youngest and healthiest flocks and continue with older flocks or flocks with lower biosecurity standards.
• Changing rooms should be equipped with showers that are mandatory for all visitors. Farm employees should also preferably take a full shower before entering the farm, and on a mandatory basis if they have been exposed to risk situations (e.g., if an emergency visit must be made after having visited another flock of older age or uncertain health status). If a visitor poses an unacceptable risk to bird health, he/she should be denied access to the poultry farm and the visit rescheduled.
• Visitors and service personnel should complete and sign a visitor log before entering the farm. Keeping a detailed record of foot traffic on the farm can be very useful in investigating the possible origin in the event of a health problem and also allows the farm owner to warn recent visitors in the event of a confirmed disease.

Figure 2. Diagram of a changing room with clearly delimited areas: (1) Dirty area (2) Transition area with shower and washbasin (3) Clean area

Cleaning and disinfection

At the end of each flock of birds, effective cleaning and disinfection is essential to reduce the number of pathogens and the risk of a health challenge before restocking the farm. This is a key part of any biosecurity program and should include the poultry houses and associated items (storage rooms, etc.), all equipment and equipment, and not forgetting the surroundings. Before proceeding to the disinfection of the sheds, it should be kept in mind that it will only be effective if all organic matter is first meticulously removed.

In any cleaning and disinfection program, the procedures to be followed should be established, detailing each step of the process. Very schematically, the different phases of the program are as follows:

• Removal of waste: live animals, dead animals, feed scraps, poultry manure, litter, feathers. Dismantling of equipment. This is the moment to use chemical products against insects or mites (while the house is still warm) and to place abundant bait against rodents.
• Preparation: flushing of the drinking water circuit followed by refilling with detergent and descaling solutions. Soaking of all surfaces with detergent solutions. Vacuuming and manual cleaning of areas that cannot be wetted. Visual control of the cleaning.
• Pressure washing of the buildings, preferably with detergents and hot water, not only internal surfaces, but also accesses, following a logical sequence: ceilings first, continuing with walls and finishing with the floor, and always from the inside to the outside. Washing of all equipment and dismountable material.
• Mounting of equipment in the shed when dry
• Disinfection: Spray all surfaces of the building and equipment previously washed with a disinfectant solution. Cleaning of water tanks and pipes to eliminate biofilm. New disinfestation.
• Visual inspection of cleaning and disinfection effectiveness
• Final fumigation

Finally, it is important to stress that, to implement a successful and effective biosecurity program, all measures must be simple, easy to understand, accepted by all people involved and monitored regularly. A biosecurity plan is often described as a chain: it may be the most cost-effective way to keep poultry farms disease-free, but all links must be in good condition!

Figure 3. Good maintenance of the footbath is essential to ensure its effectiveness.