Poultry such as layer hens, meat chickens and turkeys are very susceptible to avian influenza. Birds that have access to the outdoors will have a greater chance of coming into contact, either directly or indirectly, with wild water birds such as ducks, geese and swans. Wild birds may carry the avian influenza virus but usually show no signs of disease (the virus is found mainly in the feces and in nasal and eye discharge).
Avian influenza outbreaks pose a health and welfare concern for affected birds which are culled to prevent spread of the disease. Signs of the disease include reduced egg production, depression, cold-like symptoms, swelling of the head, diarrhoea and, in the more virulent forms, birds die very quickly.
The key to managing the risk of bird flu is preventing infection in the first place through good biosecurity, and avoiding its spread (mainly by humans) to other birds on the same farm or on other farms. Key strategies to manage the risk include:
- managing birds to ensure healthy immune system (i.e. good gut health)
- managing stocking density to avoid overcrowding and allow birds to move around freely and express natural behaviours
- ensuring bird drinking water from dams or other open sources is sanitised before it enters the shed
- regularly rotating the outdoor area (for parasite control)
- avoiding puddles or wet areas on the range
- discouraging wild birds from accessing the range area, for example by not placing feed and water sources on the range
- biosecurity measures for farm staff and visitors as well as equipment, containers, egg fillers, and vehicles
- hygiene, disinfection, and parasite management
- pest management
- maintaining litter quality in a dry and friable condition
- actively monitoring birds for early symptoms.
Development and application of avian influenza vaccines is also be a key strategy. The range area should be attractive for poultry but less attractive to water fowl to discourage them to land. Consideration should be given to placement of poultry farms, i.e. in areas with relatively few water fowl, wild bird flight paths, and low concentration of poultry farms to help reduce the spread between farms.
Rather than abandoning free-range production systems, producers should aim to manage these systems in order to reduce the risk of their birds contracting bird flu.