Dr Akos KLAUSZ
Veterinary Technical Service Manager Aviagen
By courtesy of AVIAGEN
Most broiler companies in Russia still use eye drop and intra nasal vaccine administration methods to deliver live vaccines to the birds. Such individual vaccine application methods have the benefit of ensuring that every bird receives one full dose of vaccine. However, in a commercial chicken flock of many thousand individuals, the benefits of individual vaccination can be outweighed by the increased stress caused to the birds as a result of individual catching, handling and vaccine application The impact of this on the birds is visible and measurable: reduced weight gain, poor uniformity and eventually vaccine reactions. Mass vaccine application methods are less stressful for the bird, but require careful management if they are to be as effective as individual vaccine administration.
How to make sure mass application of live poultry vaccines is effective?
The flock receiving the vaccine must be healthy if the immune system is to process the vaccine and build up protection.
Live viral vaccines can only provoke a good protective immunity, if a full dose of the intact vaccine virus reaches each individual's target cells and replicates. A few simple, but very important steps need to be followed to ensure this is achieved.
Storage
Vaccines should always be stored at temperatures of 2 - 8 o°C. Use dedicated fridges and minimum-maximum thermometers to read and record the temperatures daily.
Transport
Always transport vaccines from the place of storage to the place of administration in a dedicated cool box. Use freeze packs and a minimum-maximum thermometer to make sure vaccines are kept under optimum conditions (2 - 8 o°C). Keep the cool boxes clean, but free of chemical residues, since these can get in contact with the vaccine later and may inactivate it.
Reconstitution
Use dedicated utensils for the vaccine reconstitution: bucket, jar, and mixer and have a clean table covered with a clean plastic sheet available in the mixing area. Don't mix the vaccine on the floor or in the shed, because of the possibility of contamination. Wash hands prior to touching the vaccine vials. Utensils should be clean, but free of any chemical residue. Remember that some chemicals are designed to kill viruses and bacteria; as little as 0.3 - 0.5 ppm of chlorine can kill live viral vaccines.
Protection of live vaccines
If bore hole water is used and is treated with chemicals (chlorine or other water sanitizers), chemical treatment should be stopped 24 hours prior to vaccination. Remove bio film and scale from the drinker lines using suitable products and clean the drinkers (cups, bell drinkers, etc). Flush the lines to ensure they are free from chemical residues. Use 2 g of skimmed milk powder per litre of water in a bucket to produce a stock solution. There are commercially available vaccine protecting products mostly combined with dyes, which if used, should be added at this stage. Finally, open the vaccine vials under the water 30 minutes after the skimmed milk powder was added and mix the solution thoroughly.
Critical points of water vaccination
Make sure all drinkers / nipples work and the drinker space for the birds is correct. Measure the water consumption the previous day for 2 hours starting 45 minutes after feeding. Add 5% to this figure, to account for the increased water intake as a result of water withdrawal. Calculate the stock solution for the given medicator setup based on this corrected value. Water deprivation should start 45 minutes after the morning feeding. Remove water from the birds for 1 hour by draining and lifting up the waterlines (if possible). The aim is to complete the vaccination of the flock within 1.5 hours, up to a maximum of 2 hours. Walk the birds regularly during vaccine consumption to encourage uniform administration. If a commercially available vaccine protection and dying product is used, collect 25 birds from each of 4 different areas of the house and observe tongue staining. If more than 90% of the tongues are well stained the flock has been vaccinated correctly.
Critical points of farm spray vaccination
The stock solution is ideally made up using deionised or distilled water. Commercially available deionised water, which is produced for industrial use, can be contaminated with bacteria that can cause local and systemic bacterial infections and should therefore be boiled the day before planned vaccination. A safer alternative is commercially available still mineral water with a low mineral content.
The equipment should be operational, clean, but free of any chemical residue, and batteries should be fully charged. The type of sprayer used will depend upon factors such as the age of the chicks, the size of the operation, and the droplet size to be produced. Fans and hot air blowers should be turned off to prevent droplets being blown away from the chickens,chickens. H however, make sure that the period of time without the fans on doesn't stress the flock. The light intensity should be dimmed to calm down the chickens to ensure they are covered with the spray. Don't forget to switch the fans and heaters back on and the increase the light intensity to the correct level after spraying has finished.
Day old chicks can be spray-vaccinated in the hatchery using spray cabinets or be sprayed with pressure sprayers on the farm. If the delivery time from hatchery to farm is short chicks can be spayed while still in the delivery boxes. Make sure the particle size is not too small and that all chicks are covered with the spray. Birds should be left to dry in the boxes for 20 minutes. If chicks have travelled a long distance to get to the farm, it is better not stress them with "in-box-vaccination". Instead give them a good start with immediate access to water and feed and spray vaccinate them a day or two later. Place feed on the paper, dim the lights, shut down fans and hot air blowers and cover the chicks with a coarse spray walking across them calmly and slowly.
For priming always use a coarse spray (60 - 150 um), because small droplets (< 10 um) can penetrate deeper into the respiratory tract causing vaccine reactions in naïve chickens. After chickens are properly primed with coarse spray they can be sprayed with an atomizer producing small droplets (20 - 50 um) for boosting (e.g. Newcastle Disease Vaccine). If the droplet is too big, it will quickly sink to the floor without reaching the chicken. If it is too small, it will evaporate quickly particularly in high ambient temperate environments without reaching the chicken. Coarse droplets can be generated by pressure sprayers (knap sack sprayers) and controlled droplet application (CDA) devices. While pressure sprayers have the disadvantage of producing various particle sizes (20 - 1000 um) at a time, they are cheap, easy to use and don't need battery packs. CDA sprayers produce a narrow range of controlled droplets typically 60 - 100 um, use a small volume of vaccine, typically 1 litre and are equipped with an electric fan, which very efficiently blows the even particles onto the chicks. In summer, if the ambient temperature is high, vaccination should be done early in the morning preventing loss of droplets due to evaporation.
Hints
Avoid significantly overdosing (hot) vaccines (e.g. Lasota NDV strains) that can cause vaccine reactions. Avoid vaccinations from onset of lay until peak production. Avoid using live Chick Anemia Virus (CAV) and Avian Encephalomyelitis (AE) vaccines less than 6 weeks from onset of egg production, because these viruses can be passed onto the progeny for a few weeks causing clinical disease. Finally several vaccines can be given at the same time. Combine administration of vaccines to eliminate bird handlings causing stress and increasing the chance of Staphylococcal leg infections (e.g. Pox+CAV+ILT or combining inactivated vaccines), however don't forget, that some live vaccines will compete for the same target cells (e.g. IBV, a fast replicating virus vs NDV a slower replicating virus, etc).
