With conventional cages a thing of the past and free-range systems accounting for half of UK egg production, Rhian Price weighs up the disease.
The move to higher welfare laying systems stemming from the conventional cage ban can bring with it an increased risk of disease.
Serious outbreaks can attract unwanted consumer and media attention, which in turn can result in stricter regulatory controls being placed on livestock producers. But how can producers minimise the risks when the threats seem to be growing ever greater?
Steven Lister, poultry specialist from Crowshall vets, says good health management and disease prevention measures are fundamental.
“The maintenance of poultry health and prevention of disease in commercial poultry flocks is a constant challenge in all production systems,” he says. “The keys to success include good house design, effective management of the birds’ total environment and good levels of stockmanship.
“Co-operation between producers and veterinarians can help to establish the most effective intervention strategies through practical veterinary health and welfare planning.”
Bio-security and disease control
Bio-security is also important and encompasses a whole range of measures designed to prevent the introduction of disease at all levels, from national and regional, right down to disease prevention between chicken houses.
“Effective management interventions include the use of therapeutic agents and vaccines, terminal cleansing and disinfection, ongoing pathogen control throughout the life of the flock and effective vermin control,” Mr Lister explains.
But before management strategies can be implemented, a good understanding of the possible diseases that could affect a flock is required.
Some of the most notable are bacterial infections, such as erysipelas and pasteurellosis – both of which can result in bird mortality.
“Vermin are a significant risk factor for introducing these types of infections, so effective vermin control and vaccination of known risk sites are the most important control measures,” Mr Lister says.
Research has revealed that 80% of cases of pasteurellosis in Danish flocks occurred in free-range birds that had come into contact with wild birds.
“Pasteurellosis is mainly a condition of layers. It is not particularly easy to treat because of the problems with antibiotics and egg withdrawal times,” explains Richard Turner, of St Davids Veterinary Practice.
“The main prevention is vaccination. A licensed vaccine is available in the UK, as well as autogenous vaccines, which are made from the strain of pasteurella on the farm.”
One of the biggest perceived benefits with free-range systems is the birds can live in a more natural environment. However, the outdoors can present more challenges to bird health.
One problem is the spread of bacteria in faeces-concentrated areas.
“Trees and bushes can offer the birds protection and encourage them to use the whole range, so faeces don’t become concentrated in a specific area,” says Mr Turner.
“Another problem is the quality of water. Birds love to drink dirty water and often areas can become water-logged, so land management is one of the most important things to keep in mind.”
Single-age sites are the best option for egg production, he adds, as they allow effective cleansing at the time of depletion. They also ensure younger birds aren’t exposed to any pathogens from older ones prior to the completion of a vaccination programme.
“Quite a lot of free-range sites are multi-age. Mixing old birds with young ones is never particularly good, because they will have different immune stages.”
Mr Turner adds that the biggest disease challenge at present is infectious bronchitis, because of the range of variants present and new strains that regularly appear.
“The approach should be to make sure the vaccination programme for your birds during rearing is correct. Some people use live vaccinations during lay, which are administered through water, but this must be handled carefully and after consulting your vet.”
Top tips from top vets
• Promote good use of the range
• Ensure the premises are disinfected on turnaround
• Exclude wild birds to reduce disease exposure
• Ensure there is good vermin control
• Implement health and welfare management strategies with the help and advice of a vet
• Ensure good drainage on free-range sites, plus good pasture management