The localisation and positioning of the farm are essential considerations. Geographical regions with a high density of livestock encourage the spread of infectious diseases. The location of the farm must limit the exposure to potential sources of contamination from other farms including those transmitted via aerosols and litter or manure.
It is therefore recommended that the farm be:
- as far away as possible from other farms. A minimum of 500 meters is recommended
- away from busy roads
- away from animal transport routes
- away from slaughterhouses
- away from manure spreading areas
- protected by vegetation which can act as a barrier against airborne contaminants
- positioned downwind from any potential sources of contamination. The farm should be located opposite the direction of the prevailing winds
It is also recommended to define a secure perimeter around the site by means of a fence, wall, or barrier. This prevents the livestock having direct or indirect contact with wild animals and birds, or stray animals which may all be vectors of disease.
Site access for people and vehicles must be controlled. In this sense, a farm which is completely enclosed by a wire mesh or fence, and with a closed gate preventing entry is preferred. Signage such as the example in Figure 1 should be displayed at the site entry to dissuade third parties from entering.
The purpose of internal biosecurity is to limit the spread and reduce the infection pressure of any pathogenic agents already present on the farm. There are three main principles in establishing an internal biosecurity program:
- Isolation and sectorization
- Cleaning and disinfection
Zoning is used to limit and control access to the farm and buildings for staff and visitors as well as animals and equipment. Areas are split into public, professional and breeding as shown in Figure 2.
The public area includes the car park and rendering area. Access is not restricted to these parts of the unit.
The professional area is where only authorized people and vehicles circulate. Parking areas for vehicles that are permitted in the professional area should be positioned away from buildings and especially their air inlets and outlets. People in the professional area should limit their movements, and they should not enter the breeding area unless necessary.
The breeding area is the most secure part of the farm. Only people with the correct authority and when in full breeding clothing are permitted entry. Anyone entering or exiting this area must pass through the sanitary lock (Danish entry system).
Isolation and sectorization
An isolation unit should be available within the farm where animals can be protected from exposure to viruses, bacteria or other pathogens. If a disease is observed, the infected animal should be excluded from the main flock or herd to prevent spreading of the disease to otherwise healthy animals.
Some farms use sectors to identify and isolate animals with different infection and contamination levels, and where the immune status of the animals might be different. For example, sows, piglets, and grower-finisher pigs may all be kept in different sectors within one pig farm.
Cleaning and disinfection
In addition to isolation and using sectors, thorough cleaning and disinfection should take place regularly to limit the contamination level in the breeding area and in the buildings. A three-phase decontamination protocol is recommended: first cleaning with a surfactive detergent, followed by a first disinfection and then a terminal disinfection.
The cost of poor biosecurity
There are several factors to consider if biosecurity levels are not met.
- Pathogens may be carried to other breeding units on the farm, or to other geographical areas
- When pathogens are transmitted to other animals, the health of the flock deteriorates which increases the cost of treatment
- Animal performance decreases which degrades the Consumer Index (CI)
Although necessary, it is not enough to establish biosecurity measures only at farm level. Regional, national, and even international activities must also be considered to safeguard the movement of people, equipment, and animals as these can all contribute to the transmission of contagious pathogens, sometimes over long distances. Professionals must share health information to control contagious diseases.
Basic biosecurity principles
- Animals being introduced to a site should come from one origin and at one time.
- Any sick animals should immediately be isolated in the quarantine area.
- All vehicles and equipment should be cleaned and disinfected before entering according to the specific requirements of the site.
- Filters should be fitted to all air inlets and outlets on livestock houses.
- Human contact with the animals should be limited. A register of visitors should be kept.
- Foot baths and clean clothing should be provided for anyone visiting the breeding zone of the unit.
- Anyone entering the breeding area through the sanitary lock should pass from the diry area, through the showers and into the clean area where clean overalls, coats and footwear are provided. There should be a clear divide between the dirty and clean areas of the sanitary lock.
- The flow of materials, personnel and animals should be from the least contaminated areas to the most contaminated. This is to protect animals with an immature immune system from exposure to infectious agents transmitted from contaminated areas of the farm or from the outside.
Biosecurity measures are put in place to prevent the introduction or spread of diseases in livestock. Such measures may sometimes appear unnecessary, constraining, or expensive without any immediate benefits, but without them, the consequences can be devastating. Thorough training of all staff and personnel working on the site will help raise awareness and increase adoption of the biosecurity measures. Sufficient support should be provided during site audits and quality assurance checks.
There are many advantages to implementing good biosecurity measures including better welfare standards, higher levels of zootechnical performance and increased profitability.