DATAFILE. Spray vaccination of poultry. Introduction. Dr T Cserep

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1 I n t e r v e t P o u l t r y D i v i s i o n DATAFILE Spray vaccination of poultry Dr T Cserep Introduction Research carried out by Dutch avian virologists in the late 1970s firmly established that the most effective method of immunisation against IB at day-old was vaccination directly into the birds eyes. (Figure 1) It was found in field trials that when the vaccine was applied by eye drop directly into the eyes of one-day old chicks, 100% protection was established at as early as 2 weeks of age against intraocular and intranasal challenge with virulent infectious bronchitis virus. This research suggests that a very careful application of spray could also give rapid onset of protection. A strong reaction occurs in the gland within 2 weeks of vaccination. Lymphoblasts from the Bursa of Fabricius invade it, mature to plasma cells which then produce the all-important antibodies. At the same time, follicles of lymphocytes grow and vascularisation takes place. What makes the eye-drop/spray method so effective, when properly applied? The answer is a small gland called the Harderian gland, which is located just behind the eye in the eye-socket. Cells (lymphoblasts) from the Bursa of Fabricius migrate to the Harderian gland and establish themselves in the framework of the organ. In a maturation process they become plasma cells capable of producing antibodies after contact with the virus. Figure 1. Eye drop vaccination

2 The more vaccine virus enters the eye, the more plasma cells are produced. This results in more antibodies which give protection. Once produced, these antibodies go to work covering the mucosa and sticking to it. They are protected from the enzymatic action which would normally destroy them and they then provide the so called local immunity. This immune response occurs to the same degree in all chickens whether they have a high level of maternal anitbodies or not. This is nature s own way of bypassing maternal IB antibodies. Figure 2. Spray droplet production - hydraulic nozzle photo courtesy of Micron Ltd There is a draining tube running from the base of the Harderian gland towards the internal surface of the nicticating membrane (third eyelid of birds). At the end of this tube there is a pouch-like outlet, which is moved over the eye by the nicticating membrane. The nicticating membrane also spreads a small proportion of the tears over the eye. The rest of the tears flow down into the nasal cavity through the lachrymal duct. A large proportion of the vaccine liquid entering the eye is drained away by the lachrymal duct to the nasal cavity. From here it goes through the palatal cleft and is then swallowed inducing some degree of systemic immune response in addition. Consequently, an adequate amount of vaccine must enter the eye to start this process. The action of the Harderian gland is strongly dependent on the Bursa of Fabricius. However, unlike the Bursa of Fabricius, the Harderian gland shows no regression with age. This gives us the opportunity to boost local immunity by repeated spray vaccination even during the laying period. Although eye drop vaccination is very effective, in many parts of the world labour costs make it a very expensive method. Spray vaccination is a mass application technique which is much cheaper and has replaced it completely in large poultry units all over the world. Spray vaccination is carried out using equipment which breaks down the vaccine suspension into a multitude of small droplets, and propels them in a form of a jet or a cloud. (Figures 2& 3). The smaller the droplets of vaccine, the deeper the vaccine virus can penetrate into the respiratory system. The deeper the vaccine virus penetrates, the better the onset of protection, but also the stronger the vaccination reaction. This also depends on the type of vaccine virus used. In general, Newcastle disease viruses are capable of causing more severe reactions than for example infectious bronchitis virus, when used in previously unvaccinated birds. Figure 3. Spray droplet production - spinning disc photo courtesy of Micron Ltd The spray method is the preferred method for vaccinations against respiratory diseases because this method induces powerful systemic immunity in the form of circulating antibodies in the blood stream and local immunity on the mucous membranes of the eye and respiratory system. This level of protection cannot be achieved by water administration alone. Research has shown that locally produced immunity in the trachea is important in early protection following IB vaccination. Target: The Mucous Membranes of the eye and upper respiratory tract The aim of spray vaccination is to vaccinate the flock with the intention of bringing the vaccine into contact with the mucous membranes of the eye and/or of the upper respiratory tract. (Figure 4) How can we reach those targets? Vaccination by spray can be carried out by either coarse or fine spraying. To understand the difference between the two and to decide which one to choose, it is useful to become familiar with droplets and their behaviour in the air. Spray vaccination against respiratory diseases (ND, IB, TRT, SHS) brings the vaccine virus into contact with the birds in the most natural way. The aim of spray vaccination is to deliver a full dose of vaccine to the upper respiratory tract of all the birds in the group at the same time with minimal reaction. Figure 4. Target areas for spray vaccination

3 EMISSION Nozzle Jet emitted losses by DRIFT losses by SETTLEMENT losses by EVAPORATION Useful fraction IMPACT The DV 0.5 is also designated as Mass Median Diameter (MMD). Why the volume (=mass) is considered more important than the number of particles is clearly demonstrated in Figure 6. Most particles belong to class 3 but class 5 harbours the biggest mass. Concerning active compund, in this case vaccine virus, it is the mass (=volume) that counts. Figure 5. What happens to the droplets What happens to the droplets? Between emission from the sprayer and contact with the bird, the vaccine suspension is subject to losses. The part of the spray droplet which reaches the bird is described as the useful fraction. The losses are due to settlement, evaporation and drift, which the droplets are subject to. (Figure 5) Settlement is the loss of vaccine suspension due to large droplets falling to the ground. It is controlled by reducing the mean size of the droplets (VD* 0.5 close to 150 microns) and by grouping the birds together. *See Particle size distribution below Evaporation is a phenomenon which affects all droplets between emission and impact, causing a reduction in their size, which may go so far as to cause them to disappear. It is greater if the droplets emitted are small in size, if the ambient temperature is high and if the humidity is low. It is controlled by turning off the radiant heaters during spraying, by holding the nozzle or nozzles at a short distance from the birds (which reduces the time of travel) and by vaccinating in the morning, the coolest period of the day (low temperature, high humidity). Drifting is the loss of droplets subject to air movements. All droplets with a diameter less than 200 microns can be regarded as susceptible. It is controlled by turning off the ventilation during spraying. Under normal conditions of use, droplet sizes of 50 to 100 microns (µ) can result in droplet sizes on impact of less than 3 microns. Particle size distribution The particle size distribution of a spray or aerosol can be characterised by the VD (Volume Diameter) value. The VD value of a spray or aerosol indicates the percentage of the spray/aerosol volume, which is formed by the indicated droplets. For example: If DV0.1 = 50µ this means that 10% of the volume particles < 50µ If DV0.5 = 100µ this means that 50% of the volume particles < 100µ If DV0.9 = 200µ this means that 90% of the volume particles < 200µ Figure 6. Droplet size distribution: numbers (N%) and percentage of volume (V%) The impact of the droplets In spray vaccination the particle size will determine the deposition of the virus in the respiratory tract of the bird. Nearly all the droplets larger than 10µ (1µ=0.001mm) will be deposited in the upper respiratory tract, the conjunctivae, the nasal cavity and the upper part of the trachea. Around 80% of particles of 5µ will be deposited here as well. Smaller particles will penetrate deeper into the tract, with particles of 3µ being deposited in the trachea, the air sacs and the lungs. (Figure 7) Anterior respiratory tract 3.7-7µ Lungs and abdominal air sacs 1.1µ Posterior abdominal sacs 0.09µ Figure 7. Avian Respiratory system

4 The Impact of coarse spraying Here impact is direct. The droplets reach the bird at the end of the trajectory. The droplets emitted should strike the bird around the eye in particular, the nostrils and the mouth. Therefore the jet of a knapsack sprayer must be aimed intentionally at the head. To make this easier, it is helpful to use an extension lance of sufficient length to reach all the birds including those turned towards the operator and those which have turned their backs to the sprayer. (Figure 8) Figure 8. Birchmeyer sprayer with long lance inhaled. These may be small enough to penetrate deeply as a result of pronounced evaporation. A high ambient temperature therefore encourages postvaccinal reactions. Spray Equipment To deliver the vaccine solution onto the mucous membranes of the head and upper respiratory system we have to choose the appropriate equipment. For Coarse Spraying This is the method recommended for all day old vaccination in the hatchery or on the farms and for the first vaccination against Newcastle disease. It is also suitable for IB and TRT vaccination. Garden sprayers They are designed to be hand-held or carried on the back (types: Polyspray 2 [Figure 9] or Killaspray Courrier 8 Hozelok-ASL, etc) and have a tank of varying sizes (1 litre to 20 litres), in which the vaccine liquid is most commonly pressurized. The diameter of the outlet aperture is adjustable by tightening or loosening the screw nozzle. To achieve maximum cover in a group of birds it helps if they are grouped together in a corner or along the walls and sprayed twice on a double pass. All droplets with a diameter greater than 5 microns will remain on the surface or will penetrate but come to rest in the upper respiratory tract. Those which come into contact with the conjunctiva of the eye will stimulate the Harderian gland and those which pass through the lachrymal channel will reach maximum penetration at the larynx and the top of the trachea. Droplets of coarse spray because of their size have a tendency to fall to the ground by settlement. The impact of fine spraying Here, impact is simultaneously direct and indirect. Numerous small droplets remain suspended in the air and are breathed in by the birds subsequently. By stimulating the lower respiratory tract they form the main vaccination dose which the birds receive. To limit losses by evaporation, the spray must be aimed approx. 50cm above the birds heads in order to surround them with a mist. Due to the indirect impact, it is not as essential to group the birds together as it is for coarse spraying. Numerous small droplets will enter the trachea, the bronchi, the lungs and even the air sacs. They are responsible for stimulating a powerful immune response but may cause post-vaccinal reactions in birds with less than perfect health or carrying potentially pathogenic organisms like E.coli, mycoplasma and OR. High ambient temperature can cause problems because the birds hyperventilate with their beaks open. Under such circumstances the respiratory rate, (which is normally around 30) can reach over 170 per minute, noticeably increasing the quantity of vaccine particles Figure 9. Polyspray Although they are readily available and their cost is reasonable, they have a number of disadvantages: The pressure varies constantly as the tank empties. This necessitates regular pumping, which is time consuming and still doesn t ensure an even pressure. One way of limiting the significance of this problem is never to fill the tank beyond half way. This makes the drop in pressure more gradual. The size of the droplets has to be judged by eye and this perception naturally varies from person to person. The spray is very uneven due to the type of nozzle used. We should aim for an even spray which is neither too fine (mist) nor too coarse (shower). The delivery rate varies greatly from one machine to another and the operator should be aware of this otherwise he or she might be forced to sacrifice spray quality in order to finish on time. The delivery rate must be measured and should not exceed 0.5 litres/minute. The nozzle is fitted onto the end of a relatively short (up to 50cm) lance. As birds move away from the operator they cannot be reached properly especially if they have turned their back to the operator.

5 The nozzle and the operating pressure of pressurized spray systems broadly determine the size of the particles produced but, overall, this type of equipment will produce a large range of particle sizes (from 50 to 1000 µm diameter). One of the practical difficulties with this method of administration is that the spray particles produced only travel approximately 50cm from the nozzle. In order to vaccinate all the birds properly, the nozzle must come within 50cm of every bird in the group. Furthermore, due to the range of particle sizes produced, only a small proportion of vaccine is capable of being inhaled by the birds. The remainder is either taken up by the ocular or oral routes or falls on the ground. As a consequence, relatively large volumes of water (in the order of 15 to 30 litres per shed) are required to cover the birds. Garden sprayers should be avoided where possible in favour of improved nebulizers. This improved nebulizer produces two even jets at a constant pressure (adjusted to 2 bar in practice). This is compatible with a delivery rate which ensures correct operation (0.25 litres/minute). Metered dose spray applicators The Accudos 25 S (Micron, Bromyard, UK) (Figure 11) is a spray applicator suitable for vaccinating day old birds in boxes in the hatchery or on farms. It delivers a measured volume of coarse spray per box in the range of micron droplet size. Improved nebulizers To optimize the potential of garden sprayers, a new type of sprayer has been developed. It is the Birchmeyer Flox 10 Plus nebulizer (Birchmeyer et Cie, Kunton, Switzerland). (Figure 10) This is a knapsack sprayer pressurised in an adjacent reservoir and not, as is more usually the case, in the tank itself. (Venturi principle) The following modifications have been made: A pressure reducer linked to a pressure gauge has been interposed between the handle and the lance. This ensures that the pressure remains stable and is monitored throughout the spraying operation. The lance has been extended to a metre in length and fitted with a fork at the end. This arrangement allows the birds to be reached well in front of the operator ensuring effective spraying, whilst at the same time increasing the range of movement and spraying capacity. Two high quality nozzles with an outlet aperture of fixed diameter (0.55mm) are fitted at either end of the forked lance. Figure 11. Accudose in hatchery For Fine Spraying photo courtesy of Micron Ltd Fine spraying ensures that the vaccine virus penetrates more deeply into the respiratory system of the birds. It is therefore not suitable for the first ND vaccination. This method can be used for IB or TRT vaccinations and for the second and subsequent ND vaccinations. Atomizers There is a wide choice of models of atomizers available on the market and they use a large variety of energy sources and operating principles. The most widely used equipment is the Atomist Model 1026 BR (RL Corporation, Lowell, Minnesota, USA.) (Figure 12) fitted with an 8-litre reservoir, an electric motor and a flexible tube which enables the direction of the jet to be more precisely controlled. Figure 10. Birchmeyer with pressure reducer Figure 12. Atomist sprayer

6 Adjustments can be made through the air inlet regulator located between the reservoir and the motor and the output limiter with 3 settings located at the end of the flexible tube. When the air inlet is closed and the output limiter is at maximum, 95% of droplets produced have a mean diameter of 22µ. When the air inlet is open and the output limiter is at minimum, 95% of droplets produced have a mean diameter of 46µ. The Atomist device delivers the droplets up to 4-5 metres. Controlled droplet application (CDA) devices These devices use spinning disc atomizer technology to accurately control droplet size. They operate with very low volume of water and produce uniform droplets in various ranges. The first of these devices used for vaccination was the Turbair (Micron Ltd, Bromyard, UK) sprayer. (Figure 13) Water for spraying To avoid the undesirable effects of chlorinated tap water on the vaccines we recommend distilled or deionised water for spray vaccination. Volume of water for spray Litres/1000 birds Minimum Maximum Birds during rear Coarse Spraying Day old birds in boxes The volume of water recommended for vaccination with Atomist sprayers is litre per 1000 birds. CDA devices require much less water needing only about 1 litre per shed. For further details see the Instruction Manual produced by Micron. The above figures are guidelines only. The correct volume needed should be determined by a trial run to see how much water is required to cover adequately all the birds in the house. This will depend on the type of housing and the volume output of the particular sprayer. Vaccination of day old birds Figure 13. Turbair sprayer Its more modern version, the Ulvafan has been developed specifically for vaccination of poultry and generates droplets in the micron diameter range. (Figure 14) Vaccination of day old chicks can be carried out either in the hatchery or on arrival at the farm. For several reasons (temperature, humidity, time, trained personnel, purpose built equipment etc), the onset and uniformity of protection is better after vaccination in hatchery, therefore this is the preferred option in comparison to farm vaccination. To achieve maximum immune response day-old birds should be kept in the boxes for at least one hour post vaccination. The best coverage can be achieved using a flat fan spray nozzle which produces a virtual curtain of spray capable of covering the box evenly from corner to corner. Sprayers operating with hollow cone nozzles produce a ring of vaccine. (Figure 15) This means that the exposure to vaccine of birds in the box is uneven and often the ones in the corners are left out. Physical coverage of the birds and the volume of water administered per bird is more critical than particle size in these systems. Figure 14. Ulvafan sprayer photo courtesy of Micron Ltd The cloud of droplets leaving the spinning disc is blown to the birds by a fan up to 3 metres distance. The precise control over droplet size allows the use of low spray volumes, which significantly reduces the time required for both the preparation and the administration of vaccine. Flat Jet Conical Full Jet Conical Hollow Jet Figure 15. Different types of jet pattern

7 The volume applied must be accurately determined and repeated for each box. It can range from 200 to 400ml per 1000 birds depending on the type of equipment in use. For day old spraying, droplets of >100µ are ideal as they facilitate even coverage of the birds (smaller droplets have a tendency to drift with air movement and may not reach the box). The birds should look wet but not soaked after spraying as this can lead to chilling and high first week mortalities subsequently. Spray vaccination in the hatchery Purpose-built automatic or semiautomatic spray cabinets enable hatcheries to vaccinate large numbers of day old birds in a relatively short time. As the design of these spray cabinets varies greatly it is only possible to give general guidelines here and the instructions of the manufacturers of individual machines should be followed. It is essential to operate the system at the correct pressure and with the right type of nozzle to ensure production of large droplets (>100 microns). As previously mentioned, small droplets can be inhaled deeply into the respiratory system and can cause postvaccinal reaction (particularly with some ND vaccines). They can also be blown away by air currents resulting in partial loss of the vaccine. The size of the droplets can be estimated either with water sensitive paper (Figure 20) or with silicon oil coated microscope slides. (For details contact Intervet s Poultry Department) To have accurate information on the range of droplets produced by the spray cabinet, laboratory testing of the nozzles is necessary. The coverage of chicks vaccinated in hatchery spray cabinets can also be assessed using dyed vaccine solutions. In one practical test, a double nozzle spray cabinet showed a distinct figure of eight with an uneven spray pattern and the majority of the vaccine deposited immediately below the nozzles. Using evidence of stained feathers as the measure for vaccination, a spray cabinet with badly aligned nozzles sprayed only 80% of the birds and 20% were missed. (Figure 21) Most negative chicks were located in corners and along the sides of the box. Figure 17. Spray cabinet example B Figure 18. Spray cabinet example C Figure 19. Spray cabinet C with hollow cone jet, one nozzle partially blocked Figure 16. Spray cabinet example A Figure 20. Water sensitive paper

8 The compressed airline which operates the sprayer can be contaminated from the hatchery environment. Charcoal filters should be built into the system to prevent buildup of such contamination. Piston type spray cabinets are better in this respect allowing the use of disposable plastic pistons. Spray vaccination of day old birds on farm Equipment producing coarse spray (garden sprayers, nebulizers or metered dose devices) can be used. (Figure 23 & 24) Figure 21. Dye test in the hatchery If it is possible, a flat fan or full cone type spray nozzles should be used instead of the hollow cone ones to ensure better coverage in chick boxes. The height of the spray nozzles and the angle of spray should be adjusted to achieve maximum coverage in the box. It is also important to regularly monitor the delivery rate of the spray nozzles by using measuring cylinders. The difference in delivery rate can result in uneven vaccine cover in the chick box resulting in uneven immunity or susceptibility to infection. (Figure 22) Place the boxes next to each other on the floor of the shed to form a continuous line. If spraying takes place in a building heated with spot brooders place the chick boxes away from the brooders as much as possible during vaccination. 1 While unloading is in progress, prepare the vaccine suspension. Check that the spray produced by the nozzle is the right type; adjust the nozzle or dismantle and unblock if necessary. 2 Spray the birds methodically, box by box. The angle of the spray is critical for the vaccine to reach the eyes. Spraying downwards only wets the heads, not the eyes. 3 It may be useful if someone walks in front of the person carrying out the vaccination and taps the boxes with the foot to wake up the birds and make them raise their heads. Walk around the row of boxes and spray them from the other side as well. 4 Wait till the chicks dry up completely (approx. 30 minutes) before emptying the boxes. 5 Clean the equipment as described later. Figure 22. Difference in delivery rate Figure 23. Knapsack sprayer Figure 24. Garden sprayer

9 Spray Vaccination during rear Broilers are sometimes vaccinated with IB variant vaccine (IB-491) at days of age or in some countries must be vaccinated against Newcastle disease. For this purpose the Ulvafan sprayer or the Birchmeyer nebulizer is adequate. Layers, turkeys and breeders can also be vaccinated with this equipment, administering ND, IB or TRT vaccines. The first ND vaccination must always be done either by drinking water or coarse spray (Birchmeyer or equivalent sprayer but not the Ulvafan sprayer). (Figure 25) The Atomist sprayer is suitable for the second ND vaccination or other vaccinations during the rearing period. (Figure 26) Figure 25. Knapsack sprayer with multiple nozzle Apart from the type of equipment used, there are a few important general guidelines to follow when spraying birds older than one day. The health status of the flock should be assessed before vaccination. Only healthy birds should be vaccinated. It is beneficial to operate the ventilation system at a high level shortly before vaccination for two reasons: 1. To reduce the amount of dust floating in the air which may inhibit spray particles reaching the birds. Figure 26. Atomist in use for layers in cages 2. To cool down the shed in order to prolong the lifespan of spray particles. If the shed is equipped with an evaporative cooling system it is even possible to increase the humidity of the shed. Again this can increase the lifespan of spray droplets. Reducing the light in the shed reduces movements and other activity of the birds. In this way the operator can establish a route among the birds more easily and can target birds sitting in groups. Light intensity should be lowered during spraying as bird s movements and wing flapping create air currents leading to uneven cover in the shed. (Figure 27) Ventilation and heaters should be shut down during spraying and left off for 5-10 minutes after spraying. It is equally important to restart ventilation (and heating if necessary) when the job has been completed. Numerous flocks have suffered high mortality due to suffocation after spray vaccination because fans were not restarted. Placing one s car keys on the ventilation control panels may help to prevent this by serving as a reminder. Figure 27. Ulvafan in use for broilers Using a torch in a dark shed can prevent accidents such as stumbling over feeder or drinker lines or any other obstacles. It also helps to check the level of vaccine in the sprayer. This technique should be avoided with turkeys and layers as they may panic resulting in mortalities due to smothering. (Figure 28) Figure 28. Use of torch in a dark shed

10 Walking around twice particularly with nebulizers is strongly recommended to achieve good coverage. On some rearing farms perches are placed in the pens to prepare the birds to use nest boxes in the laying farms and also to strengthen their legs. When birds are to be sprayed around these perches the slats of the perch can take up substantial amount of the spray. To prevent this it is best to move the perches aside at the time of spraying. (Figure 29) Spraying the vaccine In a small sized shed where birds are grouped along the sidewalls the vaccinator should walk with the sprayer (knapsack sprayer, Atomist) slowly up on one side and return on the opposite side. He should use a slow side to side motion with the lance of the sprayer or the flexible tube of the Atomist. The spray should be aimed about 50cm above the head of the birds. The distance between the vaccinator and the side wall should not be more than the range of coverage of the sprayer. It is advisable that an assistant helps with of the extension cable of the Atomist. In wide buildings it is recommended to divide the house into 2-4 metre wide strips and spray the birds within that strip. It is particularly important in these types of buildings that the operator walks around twice ( double passing ) and covers as many birds as possible. Figure 29. Perches in a breeder shed Preparation of the sheds In relatively small broiler sheds two people should go through the centre towards the far end of the shed making noise so that the birds move towards the two side walls. The lights should be dimmed to a low level but enough that when the two people walk back they can avoid obstacles. The flock will tend to sit quietly alongside the wall and the dimmed light allows one person to spray properly. Spraying with Ulvafan differs from spraying with other sprayers. We must remember that this machine generates a cloud of droplets instead of a jet. As the operator moves along the drinker or feeder lines the sprayer has to be held on the side, directed towards the sidewalls and without moving the sprayer side to side. It should be aimed towards the floor at a point 3 metres from the sprayer. The size of the droplet cloud is about 3m in length and 1m in width but the cloud starts only about 0.5m from the hand of the operator holding the sprayer. In large broiler sheds where grouping the birds by forcing them to the walls is not possible, it is useful to dim the light 5-10 minutes before the start of spraying. The birds will settle on the floor in groups and the operator can walk along feeder and drinker lines and spray them. (Figure 30) Where birds are in pens (e.g. broiler or layer breeders) dimming the light before spraying is also recommended. Figure 31. Ulvafan covers up to 3 metres Figure 30. Birds settling down in dark

11 It is strongly recommended particularly for large size broiler sheds that a spraying plan should be drawn up. (Figure 32) the day before vaccination. This ensures that no areas in the shed are left out. Divide the shed into metre wide strips utilizing drinker and feeder lines as guides and plan the direction of walking and spraying. There is no harm in having occasional overlaps of spraying but if certain strips are only half sprayed, the results can be very disappointing. The teeth of the disc can be broken or distorted due to careless handling resulting in uneven droplet sizes and abnormal delivery rate. It is therefore strongly recommended that the disc is checked before the start of spraying and replaced if necessary. Once the work has been done and the disc cleaned the protective cup must be put back on. (Figure 34) Figure 34. Faulty disc Figure 32. Plan of spraying If spraying for the first time, it is beneficial to do a trial vaccination using plain water. This ensures that the correct volume of water is applied and the correct route throught the shed is made. Always check that the plastic screw holding the atomizing disc is tight enough before the start of spraying. It is very frustrating to come out of a shed and realize that the disc has been lost! (Figure 33) Not only must it be found, the shed must also be resprayed. Voltage changes affect the speed of the rotor and this will have a significant effect upon the particle size generated. To prevent this, it has to be ensured that the battery is fully charged before before starting spray vaccination Spraying sheds which are divided into pens requires careful planning and time keeping. Time spent in vaccinating individual pens can be calculated using the following equation: No. birds in pen A x 20 Total No. of birds in shed = Minutes to spend for vaccination in pen A For further details on spraying with Ulvafan read the instruction manual of Micron Ltd. Spray during lay Figure 33. Lost spinning disc Field experience in several countries suggests that spray vaccination with IB or ND vaccine during lay can be beneficial in reducing small production drops and/or egg shell quality problems caused by IB or ND challenges. This vaccination is usually done by coarse spraying. Spray vaccination every six weeks during lay boosts the local immunity on the mucous membranes thus hindering the entry of the virus into the respiratory system. The general guidelines for preparation and spraying given in the previous paragraph can be applied here as well. Reduction of the light intensity should be avoided and extra care is needed to avoid any stress which can cause a drop in egg production.

12 Maintenance of the equipment is essential Droplet generators, lances and nozzles must be systematically rinsed after each use, with water containing no disinfectant, and then dried. The mechanism must be greased regularly. The nozzles must be dismantled after each use and changed periodically (in practice when the delivery rate measured differs by more than 10% from the nominal delivery rate). Hatchery Hatchery spray cabinets vary greatly in design and therefore require different maintenance. It is essential however to drain their vaccine tank and flush through the whole system with distilled or deionised water after each use. Only disinfectants without residual effect like Clean Tab (two tablets per 4.5 litres) should be used. This disinfectant solution should be left in the system overnight and should then be flushed twice with distilled water before the next use. Nozzles also need to be checked that their hole is the right size and shape as it can have an important effect on delivery rate and droplet size. Kinked pipes and inadequate pressure can result in a spray which is too fine or gives a very poor coverage. Regular maintenance can prevent all of these potential problems Atomist After spraying the sprayer should be detached from the canister and by re-starting the motor any remaining liquid blown out of the system. The entire equipment can be dried by running empty for a few minutes. The canister should be washed out, dried, remounted and locked in a dry place. After prolonged use dust can build up in the electric motor which can become a biosecurity risk. It is therefore advisable to dismantle the sprayer and remove the dust from it. Ulvafan After vaccination is complete wash out any residue in the spray bottle with clean water. It is also recommended to spray out a little water to clean the disc and nozzle. Occasionally it may be necessary to remove the atomizer disc and clean with a soft brush. If the sprayer is used frequently dust can start to build up on the fan and its guard. It becomes necessary to clean them thoroughly particularly if the sprayer is used by several farms. For further details see the manual supplied with the sprayer. To prevent build up of mould inside the container of the sprayer it must be stored dry. Nebulizers After each use nebulizers should be rinsed twice with distilled water which should also be pumped through the tube, lance and nozzles. It then has to be dried by running empty. The nozzles must be dismantled and any foreigh material which might block them removed. Health and Safety Do not touch any part of your face with vaccine on your hands. Wash and disinfect hands after re-constitution of vaccine and completion of vaccination. When spraying a vaccine, to avoid hay-fever like reactions in some individuals, well fitting masks to EN149FFP2S standard or better and eye protection to BS 2092 standard, must be worn by the operator and staff. We are aware that not every aspect of spray vaccination vaccines has been covered within this article. The variety of hatcheries, farms and type of equipment is so big that it is impossible to discuss all the possible variations within the limitations of one article. We do hope however, that the most important points of this area have been covered and we were able to give you some general guidance on spray vaccination technique /05/02 Reproduction of this document in part or whole is prohibited without the express wish of the authors and Intervet UK Ltd. Further copies of this sheet are available on request from Intervet UK Limited Intervet UK Limited