BVPA Working Group Recommendations for Mycoplasma Management in Gamebirds
The BVPA gamebird Mycoplasma project has confirmed that Mycoplasma gallisepticum (MG) plays a central role in respiratory disease in pheasants and partridges. Its effects vary depending on the presence of other factors. These include the presence of other infectious agents (viruses, bacteria) affecting the respiratory tract, other intercurrent diseases that can stress the birds and also a range of non-infectious factors. Many of these non-infectious factors relate to the management of the birds, including stocking density, hygiene, feeding, origin of the birds, whether birds from different sources are mixed etc.
The British Veterinary Poultry Association (BVPA) working group recommends the following:
1. The source of the breeding stock should be known and breeding birds should preferably be over-wintered on the breeding site or in a safe location and transported directly to the breeding site.
2. Breeding birds, both cocks and hens, should be managed, handled and transported in a stress free manner leading up to and during the breeding season.
3. Any outbreak of respiratory disease in breeding stock (cocks or hens) should be investigated. Not all outbreaks involve MG and many outbreaks are multifactorial and may or may not involve MG. If MG is confirmed action should be taken to minimise transmission either horizontally to other stock or vertically through the egg. Any breeding birds displaying clinical signs of respiratory disease, including conjunctivitis, should be culled.
4. If non over-wintered birds are used for breeding, they should ideally be from a single source. If such birds are obtained from mixed sources, they should be kept in separate breeding pens and not mixed.
5. Any outbreak of respiratory disease in non over-wintered breeding stock should be investigated and action taken to minimise transmission, as in 3. above.
6. Inactivated and autogenous MG vaccines may reduce or mask clinical signs in breeding birds, but there is no certainty or evidence that they will prevent either horizontal or vertical transmission of MG.
7. The working group very strongly recommends that live MG vaccines should not be used in breeding birds, because of the risk of transmission of the vaccine strain to other birds and possible reversion to virulence. As with all vaccines, there is no guarantee that they will prevent either horizontal or vertical transmission of MG in gamebirds.
General recommendations (apply to gamebirds of all ages)
8. Veterinary Health Plan: it is recommended that a veterinary health plan is drawn up to cover all aspects of health and management of the birds with specific recommendations on MG risk reduction.
9. Different ages, sources and species of birds should not be mixed together in the same pen.
10. A single supplier for purchased birds is recommended. If more than one supplier is used, the birds should not be mixed together. If breeding birds are supplied, the supplier should be asked about their MG status.
11. Strict attention should be paid to biosecurity particularly for breeding birds and on the rearing field. This includes restricted access of visitors, provision of footwear and protective clothing and strict exclusion where possible of wild bird access.
12. Particularly care should be taken to prevent wild birds accessing open drinkers and feeders.
13. A vermin control plan should be in place to exclude rats.
14. Good standards of hygiene and cleanliness should be maintained for all ages of birds including of water supply tanks and pipelines. Consider using appropriate water sanitisation.
15. Stocking densities for birds should not exceed available recommendations for the appropriate stage and type of bird.
16. All outbreaks of disease should be investigated and appropriate treatment and control initiated, both for respiratory disease and other diseases. Not all cases of respiratory disease involve MG and many cases are multi-factorial and may or may not include MG – hence the need as in 3. above for a full investigation.
17. Outbreaks should also be recorded to allow for end of season review and targeted forward planning.
Mycoplasma gallisepticum (MG) is a common problem and vets, game farmers and shoots need to work closely together to try to reduce risks. If keepers or farmers think they have an issue they should always discuss every case and outbreak with their vet. We all need to be open and tackle this together as an industry.