PART 1: BIOSECURITY IN POULTRY
The definition of biosecurity started as a set of preventive measures designed to reduce the risk of transmission of infectious diseases in crops and livestock, and quarantined pests and invasive alien species. This article seeks to highlight some of the steps that have been taken by the poultry industry in the face of disease challenges. Many of these measures can be adapted and implemented in other livestock production systems.
The poultry industry has led the way in biosecurity implementation for many years due to the high-risk disease challenge posed to the economic viability of the industry. Poultry farms have high population densities with individual flocks having relatively short productive lifespans. This coupled with narrow profit margins on eggs and meat that are produced means any decrease in production efficiency seriously affects the financial return gained from a flock. In order to maximize the financial return of every flock, poultry producers must ensure disease challenges are kept to a minimum, flock immunity remains strong and good husbandry is practised at all times.
Not all biosecurity measures that are practised in the poultry industry can be practically implemented in other livestock production systems, but the basic principles remain the same and are as follows:
- Cleaning and disinfection
- Herd/flock immunity
- Isolation
- Traffic control
- Pest control
- Mortality disposal
Poultry diseases are controlled by biosecurity, veterinary health care, complete vaccination programs, a high-quality diet, enclosed housing, and a high standard of farm and bird management.
- Cleaning and disinfection
Thorough cleaning and disinfection are possible on poultry sites that practice an all-in-all-out policy.
The site can be properly cleaned with appropriate chemicals to reduce the population of pathogens, while the lack of susceptible hosts further hinders these organisms’ ability to survive in the environment. Cleaning and disinfection remain important while a flock is present on the site with measures such as boot dips and equipment disinfection being implemented. Practices such as showering before entering sites, washing the dedicated protective clothing and vehicle disinfection are forms of washing and disinfection but fall more accurately under the “Isolation” heading.
- Flock Immunity
Disease prevention is a balance between reducing the disease challenge presented to the bird and improving the bird’s immunity to a specific disease challenge. The realisation that it is not practically possible to completely prevent flocks kept in a commercial setting from coming into contact with pathogens led to the widespread development and use of vaccines. The application of vaccines and the outcome in terms of serological results are monitored continuously in the poultry industry to ensure a sufficient level of flock immunity is reached and maintained.
- Isolation
Isolation is arguably the most important biosecurity principle to enforce but is also the most difficult to achieve on a continuous basis. Isolation begins with the farm’s geographical location and layout. Proximity to other poultry farms or main roads makes complete isolation far more challenging. The farm layout must allow for sufficient space between sites to hinder disease spread from one site to another. Functional separation of sites is just as important as spatial separation. Each site must be a fully functional unit with its own staff and equipment. Movement of staff or equipment between sites guarantees the spread of disease. Fencing is important for limiting human and animal movement.
Poultry farms ensure vehicles park on the boundary of the farm or are disinfected if they must enter the boundary fence. Staff and visitors shower and are provided with farm-specific personal protective clothing including boots before entry. Farm-specific protective clothing is washed on-site and never leaves the farm. Previous contact with poultry must be declared and a movement matrix is followed which does not allow for the direct movement of staff from a more contaminated area such as the abattoir to a less contaminated area such as a breeder farm or hatchery.
Showers and clothing changes are used to reduce the pathogen load that can be introduced onto a site. Boot dips and hand washing facilities are other important measures used to create barriers to pathogen introduction and spread on a site.
All equipment used inside the poultry houses is cleaned and disinfected prior to entering and after exiting the houses and should not be shared between farms.
- Traffic control
Only movement required for the maintenance of the production facilities and care of the livestock is allowed on the farm. Warning biosecurity signs are displayed at all entrances to poultry housing areas. Any meeting that does not need to occur on the production unit is held off-site. Records are kept of visitors and their previous movements to ensure traceability. Human movement must be from the youngest flocks to the oldest flocks and from the healthiest flocks to the least healthy flocks.
- Pest control
Preventing contact between poultry and wild birds is crucial due to the many diseases wild birds carry. Keeping houses as rodent-proof as possible and following a comprehensive pest control plan are required to decrease the risk of diseases being introduced by rodents.
The pest control plan should include insect control as flies and mosquitoes have also been shown to be vectors of disease. Ground maintenance is aimed at keeping vegetation short and unattractive to wild birds and rodents. Proper water run-off to prevent water pooling is also crucial as standing water attracts pests. Feed spills must be cleaned up swiftly or preferably prevented entirely as they are also a risk for attracting wild birds and pests. Any wild bird nesting sites on- or near the poultry houses must be removed.
- Dead bird disposal
Mortalities are a possible source of disease and a poorly managed disposal site can also attract wild birds/animals. Mortalities are removed from sites in sealed plastic bags by a designated person/vehicle. On-farm incineration or composting are options but the disposal site should be sufficiently far away from the production sites that it does not pose a disease risk. A central area on the boundary of the farm where all mortalities are stored for removal is also a good option. Mortalities may then be removed by a third party without entering the farm. Mortalities that are removed from the farm may go for composting, incineration or predator feed. In a disease outbreak situation, mortality should not leave the farm. Mortalities are monitored via post-mortem for disease.
- Treatment of sick birds
It is recommended that farmers have a good understanding of the microorganisms that are responsible for disease outbreaks. In the case of bacteria, continuous evaluation of sensitivity to different antibiotics is recommended through Minimum Inhibitory Concentration (MIC) monitoring. This ensures that the correct antibiotic is used to medicate sick flocks and reduce the risk of Anti–microbial resistance (AMR) developing on poultry farms. Cognisance must always be taken of the withdrawal period recommended by the supplier of the medication and must be strictly enforced in order to adhere to food safety principles. v
REFERENCE
A quick guide to the application of Biosecurity on a Poultry farm. SA Poultry Association.