AI Is back

Dana Simpson DVM MRCVS, St David’s Poultry Team

 

We have unfortunately seen the return of Avian Influenza cases recently. Numerous cases of HPAI, mainly H5N1, have been confirmed in different parts of the UK and Ireland. 3km and 10km Temporary Control Zones have been put in place surrounding the premises.

The initial source of Avian Influenza is likely to come directly or indirectly from wild birds, particularly waterfowl. At present the virus is also being detected in bird species (e.g. Mute Swans, Curlews, Mallards) which are not migratory, this is highly indicative of secondary infection. There may also be wild birds who were infected previously and may not be showing clinical signs or mortality at present. 

Spread between poultry premises is most often due to the movement of people, products, poultry manure or equipment. The virus can spread quickly between flocks if biosecurity is poor. The main risk is posed by people carrying infected faeces into the bird area. Good biosecurity measures such as a change of footwear or the presence of foot dips are just a number of steps that can be taken to help reduce the risk. 

At present (17 November 2021) an AIPZ (Avian Influenza, Prevention Zone) is in place in GB and Ireland. The aim is to reduce the risk of transmission of Avian Influenza to poultry and other captive birds from wild birds or any other source. The AIPZ means all bird keepers, including pet birds and captive birds, are legally required to comply with the minimum biosecurity measures set out by the government. This is especially relevant if your birds are in a higher risk area. 

Biosecurity measures include:

- Restricted access for non-essential people / visitors

- A change of clothing and footwear before entering bird enclosures

- Vehicles entering the site will need to be cleaned and disinfected prior to accessing the site. Limit these to essential vehicles only.

- Site vehicles need to be cleaned and disinfected regularly

- Enhanced vermin and pest control

- Disinfectant foot dips containing approved disinfectant at the advised concentration

- Prevention of access to standing water by the poultry and water ingress into the poultry holdings

For more information, please visit the website below where you can also find a biosecurity self-assessment checklist to help you identify any areas that may need improvement. 

Avian influenza (bird flu) - GOV.UK (www.gov.uk)

It is highly recommended to register your poultry, even if only kept as pets, so you can be contact during an outbreak. This is a legal requirement in the UK if you have 50 or more birds. Poultry includes chickens, ducks, turkeys, geese, pigeon (bred for meat), partridge, quail, guinea fowl and pheasants. There is a text alert service available which can be signed up to by texting BIRDS to 67300.

Several confirmed HPAI cases in the UK at the start of the year had been attributed to either contact with wild birds or water ingress into the birds’ housing. The latter can occur through leaking roofs, cracks in the walls etc. Making sure the fabrication of the house/holding pen is sound and waterproof is essential. 

It’s the small things that make all the difference so remain vigilant. For example, if a toolbox, bucket or other equipment has to be brought into the bird house for maintenance reasons, make sure it is thoroughly disinfected prior to entry. It can be dipped in the foot bath, wiped down with disinfectant wipes or sprayed with a hand spray containing alcohol/disinfectant solution.

It helps to keep extra boot covers / wellies and boiler suits on site in case of essential visitors entering the bird area. 

Keeping a spare sprayer with disinfectant solution in the egg store for use after each egg collection to spray the area the ramp has touched down on and the trolleys have moved across can further help reduce any potential risks. 

Keep all other non-essential vehicles out of the bio-secure area where possible. 

There are a couple of strains of Avian Influenza known to be circulating in the UK at present. Early detection can help prevent further spread of the disease. It helps to familiarise yourself with some of the clinical signs of bird flu. In laying hens these tend to be increased mortality, diarrhoea, sick looking birds, respiratory distress, dark discolouration of the combs and a drop in production often with shell quality changes such as pale eggs and soft shells. Very early signs can be as insidious as a drop in feed or water consumption. It is important to remember that different strains can clinically manifest in a variety of ways and not all signs are present at the same time or in every affected flock. With that in mind it is best to speak to your veterinary surgeon if you have any concerns and they can advise on the best course of action if you suspect disease in your flock. 

Should you find any sick or dead wild birds, keep any pets away and do not touch them. Notify the competent authority should you find any dead waterfowl or significant numbers of other birds.

Further details can be found in the DEFRA booklet online which describes what is expected of the bird keeper. www.gov.uk/guidance/avian-influenza-bird-flu

During the HPAI outbreak that occurred at the start of this year a housing order was brought into force by legislation as an aid for controlling the disease. Housing orders are enforced to protect the health and welfare of the birds. The housing order also aims to protect the economics of the industry.

Eggs can be marketed as free range for up to 16 weeks whilst the birds are being kept inside. In newly placed flocks this starts from the time the pullets are placed on the laying site, not when production starts.

In the event of a housing order there are challenges to overcome when a flock that is accustomed to being let out a certain time and ranging freely is suddenly kept in. If a proposed housing order has been announced, and you have a few days to prepare, then varying the times that the pop-holes are opened during that lead up period may give you an idea of how the birds will react and what you may have to do to mitigate against the effects.

Ventilation can be challenging in the winter months when the pop-holes are closed especially in naturally ventilated houses. Poor ventilation can adversely affect litter quality which in turn can lead to an increase in ammonia levels and associated health issues as well as proliferation of parasites such as coccidia and worms inside the house. In automatically ventilated houses the ventilation systems can be adjusted to prevent deterioration in litter quality and your ventilation consultant should be contacted for advice if required. Wet and badly capped litter should be removed from the house and the bedding material replenished frequently. Continue to monitor for worm eggs. If there is a cessation in the worm egg count service due to AI, routine worming should be considered during the housing period to mitigate any worm associated health and production issues. 

Housing can induce stress which may lead to behavioural changes and aggression. Injurious feather pecking can develop and once this behaviour is established, it can be very difficult to control. Reducing the lux level of lighting within legal levels can be a useful tool in calming the birds and preventing bullying. Adequate enrichment should always be in place –especially destructible products such as alfalfa bales and pecking blocks. Grit given at 7g/bird/week sprinkled on the scratch area may help keep the birds occupied and helps keep litter friable as they scratch about to find the particles.

Smothering incidents were not as common during the last housing order as many had feared. However, it is advised to monitor the birds often, especially around the times when the pop holes would usually open and crowds of birds should be broken up by walking the scratch area. The placement of ramps or other objects which stop hens crowding in certain areas can help stop deaths due to smothering. Electric fences should only be used as a last resort and after discussion with your veterinary surgeon who may have to write a letter to allow for a derogation for use depending on the age of the flock.

Keeping the hens in increases infection pressure for diseases such as Infectious Bronchitis (IB) and can exacerbate any associated clinical signs. IB is a coronavirus and as we are by now all aware can spread more quickly in closed areas. The majority of flocks in the UK are vaccinated with live IB vaccines in lay and this should continue during any lockdown period by your usual method of application.

Using nutraceuticals in conventional flocks can help support the hens’ health and there are also solutions available for organic production systems. These can help especially if the birds are experiencing stress due to being housed. Please contact your veterinary surgeon for advice on suitable products and if you have any concerns about how your birds are reacting to being kept in.

House temperatures often rise due to the birds being housed, even in the winter months. This in turn will result in increased activity and proliferation of the red mite population in the house. Monitor the red mite levels in the house closely and speak to your veterinary surgeon about the best way to control the red mite population in your house. 

Avian Influenza can cause serious bird health and welfare issues and have a devastating economic impact on poultry farmers. The views and opinions expressed in the article are just that, they are generic and may not be appropriate to your situation. Any actions taken in regard to AI must be done in discussion with the appropriate veterinary and government consultants and should be appropriate to your farm and specific situation.