24th October 2005

Welfare concerns associated with Avian Influenza

Your letter of 13th October to Christopher Wathes has been passed to me as chairman of the newly formed Pigs, Poultry and Fish Standing Committee of FAWC. You have asked for FAWCs advice on two areas relating to welfare aspects of avian influenza as a matter of urgency and have indicated that a rapid, if brief, response would be preferable at this stage, followed by a later more considered response.

We have considered this matter in general terms via email correspondence in advance of our next meeting on 25th October and I have also asked the FAWC Slaughter Group for their comments especially in relation to question 2, as they are currently examining white meat slaughter, including emergency on farm slaughter/killing of poultry.

Our comments below must therefore be seen in the light of these timescales and can only be considered as interim comments which we hope will address your immediate concerns.

FAWC has previously raised its concerns for animal welfare arising from control measures put in place in the event of outbreaks of notifiable disease (e.g. Foot and Mouth Disease). These concerns have centred on welfare problems associated with enforced confinement of stock, inability to move flocks/groups to slaughter or alternative accommodation, and methods and skill of on farm emergency killing. The current situation relating to the emergence of avian influenza in poultry flocks in Eastern Europe has again brought such concerns into sharper focus.

Question 1: What are the likely welfare consequences of an emergency requirement under the Diseases of Poultry Order 2003 for poultry to be kept in their living quarters or such other place where they can be isolated?

The aim of such an emergency procedure would be to prevent the likelihood of commercial poultry having contact with wild birds (especially migratory species) and their faeces, and hence virulent avian influenza virus. FAWC would cautiously support such a proposal, if Defra considered that the risks posed to the national flock were significant. Clearly prevention of outbreaks of highly virulent avian influenza infection in commercial poultry and associated animal health problems would have obvious welfare benefits. However, this approach must be on the basis of a well argued risk benefit analysis.

In terms of welfare consequences of such confinement, these are likely to be variable, dependent on the time of year, ambient temperature and production system employed, but could be significant. The production systems involved would be likely to relate to free range layers, broilers, turkeys, ducks and geese.

In the case of most commercial layer, broiler, turkey and duck farms it is likely that current housing provided for the majority of such stock would be adequate in terms of stocking density, ventilation and provision of feeders and drinkers as such systems are already designed for overnight confinement. Specific problems could be presented for most goose flocks and some duck flocks where overnight housing is not normally provided. Such stock may need to be transferred to accommodation which may either not be immediately available or “fit for purpose” other than in a very short term emergency situation. There may be specific problems for small domestic poultry keepers (DPKs) where birds are allowed to range extensively during the day with housing being designed purely as overnight roosting accommodation.

Therefore, most broiler, turkey and duck flocks could probably be housed successfully although some degree of destocking/culling may be necessary on individual cases if it was considered that housing was insufficiently served by ventilation or other services for daytime confinement. Provision for sourcing and application of any necessary additional litter bedding should be considered. High standards of husbandry and monitoring with veterinary supervision would be essential. This monitoring must be maintained for as long as birds are confined. Should adverse welfare effects be detected (e.g. feather pecking, respiratory or heat stress) then appropriate treatment with an option to cull birds should be part of contingency planning.

The physiological “stress” of sudden confinement for free range egg layers, and to a lesser extent meat birds, would be greatly influenced by the age of the flock, but could be significant. A point of lay flock which had not been accustomed to regular ranging could probably be confined without significant ill effect as long as house temperatures were not excessive. However, an older flock that had been ranging successfully for some weeks would be likely to experience stress and adverse behavioural effects. This could be manifested through an increase in vices such as feather and/or vent pecking or may precipitate conditions such as acute egg peritonitis which could result in a significant increase in mortality.

It would appear that there are few changes in provision of extra facilities that could be rapidly implemented to avoid such consequences. We understand that in Holland, following their decision to house free range layers, bird-proof verandas adjacent to popholes were recommended. For these to be effective they would need to be solid roofed to reduce the likelihood of exposure to wild bird faeces. In addition, the flooring of such verandas would need to be well drained and littered to ensure conditions underfoot were suitable.

The logistics of quickly providing such verandas on a larger scale are considerable, and construction of what would need to be substantial structures would be difficult and likely to precipitate the stressful consequences of confinement already identified above.

In conclusion, FAWC would consider that a decision to suddenly house poultry flocks could precipitate significant welfare problems dependent on the age or type of flock and facilities available. The likelihood of being able to provide adequate extra facilities or housing rapidly and effectively seems remote. As a consequence, any decision by Defra on confinement of such flocks must take these concerns into account. The likelihood of adverse welfare effects would then need to be balanced against advice to Defra by scientists and bird experts on the likely risk of introduction of virulent avian influenza.

Should a decision be made that it was necessary to house such flocks then the highest standards of husbandry and stockmanship would be necessary to minimise any welfare effects. Close monitoring of confined flocks is essential and must be real and continuous. Monitoring should take account of welfare outcomes of such confinement with the option to cull flocks on welfare grounds, preferably with a funded welfare disposal scheme as part of the contingency planning. FAWC would recommend that Defra discuss these options with industry representatives at the earliest opportunity to help assess the likely impact and be advised to highlight the potential problems to producers such that contingency options can be planned in advance. It is likely that most of the larger companies will already have been exploring options, but dialogue with Defra at this stage would be advantageous.

Question 2: How could large poultry flocks be killed to minimise welfare insult to the birds whilst achieving the aim of rapid killing?

It is clear that limiting the spread of avian influenza infection from the first index cases is aided by the prompt slaughter/killing of stock on infected premises as this is likely to rapidly reduce viral load in the environment. Most countries already adopt a rigorous stamping out policy to control the disease. This can be difficult depending on the number of birds involved, the type of housing (e.g. cages and deep pits) and the size and age of birds involved (e.g. market weight turkeys). There needs to be consideration given to slaughter of known infected flocks and those categorised as “dangerous contacts”.

Assessment of what constitutes a dangerous contact must be accurately established on scientific grounds to avoid the unnecessary slaughter of healthy animals, whilst at the same time offering the best chance of success to the control policy when using “area culls”. There is also an over-riding requirement that techniques should be humane and ensure the highest standards of animal welfare. When considering techniques a careful balance must be struck between the necessary speed of the procedure and the skill of its implementation.

Methods to consider include:

• Lethal injection. This may be feasible in small backyard flocks only, undertaken by a veterinary surgeon.

• Neck dislocation (manually or by a device). This may be possible for flocks up to 10,000 birds, as long as suitably trained staff are available.

• Concussive humane killers. Very useful for killing large numbers of larger birds (e.g. turkey breeders and commercial meat birds) but a contingency plan must ensure there are sufficient killers available. Repeated use over a short period could cause overheating and inefficient functioning of equipment. There would be a need to source spare parts and ensure staff are able to undertake the necessary “running repairs”.

• Toxic agents via the feed. Practical experience suggests that products such as alphachloralose are not effective in sick flocks due to reduced feed intake and palatability problems. The possibility of other products administered via the drinking water might be explored.

• Gas stunning or killing, using carbon dioxide or carbon monoxide. (Hydrogen cyanide is probably a humane alternative, but has human safety concerns and requires long exposure times for the birds). Small boxes containing carbon dioxide into which birds are placed can be effective but it is estimated that this could only kill about 1000 birds per day. Large containers with carbon dioxide may be better but there is a danger of suffocation rather than true stunning depending on the rate of adding birds and the maintenance of the gas mixture. Gassing birds in situ with carbon monoxide or carbon dioxide has been used. This is considered by some to be humane although turkeys seem to find carbon dioxide more aversive than layers. The practicalities depend on house type (are they air tight or are there large amounts of dead space as in deep pit laying houses?). In particular, open-sided pole barn accommodation, especially for turkeys, may prove difficult to make airtight without prior thought and planning. Some problems have been reported in generating gas from liquid carbon dioxide although these engineering problems can probably be overcome but need to be considered, prior to, rather than during an outbreak. It must be borne in mind that carbon dioxide may not be effective for slaughter of ducks, due to breath holding or other behavioural effects. We understand that DANI (Department of Agriculture, Northern Ireland) has undertaken the pilot killing of a house of end of lay hens with carbon dioxide and note that Defra is looking in detail at this aspect. As this is an area at least theoretically offering the most rapid and effective technique for killing large numbers of housed birds, then FAWC would wish to continue dialogue on this area, to explore the most appropriate methods of gas generation and application, and monitoring of the effectiveness of killing. In addition, it must be remembered that a large number of housing types may not be gas leakproof and this would greatly reduce the efficiency of this technique. Further thought must be given to the special considerations of gassing large numbers of day old chicks or unhatched embryos in hatcheries, or the use of other techniques.

• Mobile killing lines. The development of a mobile killing line with a shackle line for hanging birds prior to electrical stunning in a water bath is in progress. FAWC would wish to see this used as electrical killing rather than stun only. These can be set up logistically (again with planning to avoid unwanted lag phases) and it is estimated such systems could kill between 6,000 and 10,000 birds per hour. Experience from the recent Dutch outbreaks is that birds may need to be taken out of the house to the equipment which may contribute to dust spread from site to site. This clearly depends on the density of poultry in the area. Also it must be remembered that this puts the killing operation on show to the public which may make certain methods unacceptable. Whichever technique is used, there must be contingency by legislators to commission and store the necessary equipment and consumables. FAWC understands that such equipment may already be “available” from Holland. However, any effective contingency plan must ensure that whatever the source, that such equipment is readily available to be deployed without delay.

In conclusion, there are a variety of options available for different classes of stock and housing type. The choice of technique must depend on local conditions, but the overriding concern from a welfare point of view must be adequate planning, and the use of personnel adequately trained in that technique. Any staff involved in the process must be closely and effectively monitored and assessed by Defra veterinary officers. Consideration must also be given to contingency plans for disposal of carcases, as this must be linked to the killing process. If there is inadequate planning on disposal techniques at this stage, it could hamper or delay the killing of large numbers of birds.

I hope that these comments are clear and helpful. As indicated above these are preliminary observations. We will take the opportunity to consider the matter further at our meeting next week, but in the mean time if you require any further input or clarification of any of these points then do not hesitate to contact me via Richard Aram at the FAWC Secretariat.

To reflect our advisory role to England, Scotland and Wales, this letter is being copied to officials in the Scottish Executive Department for Environment and Rural Development and the Welsh Assembly Department for Environment, Planning and Countryside.

Pigs, Poultry & Fish Standing Committee, FAWC