Vaccine Administration to Poultry Flocks

Planning and attention to detail resulting in better administration will improve disease control and therefore economic performance of poultry. The following is an overview of the principles of poultry vaccination.

Vaccination Techniques

Flock sizes of commercial poultry operations can be as high as 30,000 birds in a single air space. For this reason it has become necessary to evolve effective methods of mass vaccination. The aim is to vaccinate a high enough proportion of the birds in the flock, to prevent or minimize the effect of a particular disease.

The proportion of the birds that need to be effectively vaccinated will vary according to the infectious agent involved and the current epidemiological situation with respect to that agent. In many situations, vaccination may only be employed as a means of minimizing the economic impact of a disease rather than total prevention in 100% of the flock.

Types Available Vaccine

There are two main types of vaccines available for poultry:

1. Inactivated vaccines

Again, due to flock size, the most widely used vaccines are live attenuated virus vaccines which can be administered to birds by techniques which are practical within the limitations of the production environment. This is usually by means of the drinking water or by spray application, though some live vaccines require individual application by eye drop or administration by injection.

2. Live attenuated vaccines

Inactivated vaccines are usually employed in breeding or laying stock and require individual administration by injection. All contain some type of adjuvant in order to optimize the immune response to the antigen. Commonly used adjuvants include mineral oils and aluminium hydroxide.

Administration Techniques

• Transfixion and scarification (cutaneous route in the wing web or foot)

• Spray/nebulisation - at day of age. Birds in the housed environment

• Injection - intramuscular or subcutaneous

• In-ovo administration

• Drinking water

• Eye drop

Transfixation and Scarification (Cutaneous Route)

This method delivers the vaccine into the skin thickness and is the method used exclusively for fowl pox vaccination, though avian encephalomyelitis is often combined with the fowl pox vaccine. The site most widely used for application is usually the skin of the wing web (using a special two pronged, grooved applicator) though scarification of the skin of the thigh and the foot can also be used. It is very important to ensure that fowl pox vaccine does not come into contact with the eyes or mouth of the birds. This can lead to lesions appearing in these organs.

In practice the most common complication can occur if the vaccine is applied to the skin under the wing where birds occasionally place their head when sleeping. Birds can subsequently develop lesions on the head that may be severe enough to affect the mouth and eyes with subsequent adverse effects on food and water consumption.

Care must also be taken to remove all used vaccine vials and scarifying equipment from the shed after vaccination as birds will peck at these items which can also lead to oral lesions.

Spray Administration

Administration of respiratory virus vaccine by spray is another very effective method of vaccination. Spray administration is employed in two situations that are distinctive for both practical and technical reasons. These are:

• Spray administration to birds in poultry houses
• Spray administration to day old birds in delivery boxes

Spray administration to day old birds in delivery boxes

The day old birds contained in delivery boxes represents the situation where we have most control of the birds in terms of our ability to administer vaccines. Birds are in groups of 80-150 and their close proximity facilitates physical lateral transfer of vaccine.

The physical size of birds does not facilitate the delivery of vaccine directly to the respiratory system, as no currently available equipment is capable of producing a consistent particle size capable of inhalation.

The spray employed should be capable of distributing the vaccine evenly over the birds. The volume applied must be accurately determined and repeatable for every box and can range from 7ml to 40ml per 100 birds depending upon the vaccine and particular spray equipment in use.

Spray Administration to Housed Birds

Injection

The site of administration is most commonly into the breast or leg though the lower neck can also be used. Accuracy of placement of the needle is critical as incorrect placement can lead to granuloma formation, lameness, head swelling or liver puncture depending on the injection site. The method and care of handling birds during this procedure is also important as this can contribute to lameness in birds.

Intramuscular or subcutaneous injection is the most common route of administration employed for oil and aluminium hydroxide adjuvanted vaccines and some live vaccines. Vaccine is usually available in 500 or 1000 dose bottles, which feed an automatic syringe at a preset dosage that facilitates vaccination of large numbers of birds.

In-ovo Administration

This is a process by which vaccine is administered into fertile eggs via the air cell at between 17.5 and 19 days of incubation using a special machine.

The system has proved to be effective for the administration of Marek's disease vaccine, certain types of infectious bursal disease vaccine and may be appropriate for a number of other types of live vaccine. This is a rapidly growing area of vaccine technology which will generate a number of other vaccines developed specifically for in-ovo administration.

Drinking Water Administration

Drinking water administration is an appropriate method of administration for most live vaccines, particularly for diseases such as infectious bursal disease and avian encephalomyelitis where the target organ is the gut. The presence of a choanal cleft in poultry also allows this route to be employed for most respiratory virus vaccines, vaccine virus gaining entry to the nasal cavity from the mouth via the cleft.

Feed and water intake are closely linked in poultry, therefore presenting food will stimulate water consumption. Water deprivation can also be useful, however this must be used with caution as excessive deprivation can stress the birds to a level, which can predispose disease and adversely influence vaccine efficacy and feed efficiency. Controlled lighting will affect water consumption by influencing activity and feeding patterns.

Live vaccines by their nature have a limited lifespan that must be taken into account during administration. As a rough guide 1.5 to 2.0 hours is a typical period of time over which live vaccines should be administered. The aim should be to present the vaccine in the water to all the birds in the colony over this 1.5 to 2.0 hour period.

Eye Drop Administration

Eye drop administration is probably the most effective (but labor intensive) means of administering live respiratory virus vaccines to birds. Each bird is individually handled and receives a full dose of vaccine. The process facilitates both local and humoral immunity due to the presence of the Harderian gland behind the third eyelid. Eye drop diluent is available from vaccine manufacturers for use with certain vaccines and is presented in an easy to use bottle, which usually contains a dye in order to assess the efficiency of administration. Birds dosed effectively will show staining at the nares shortly after vaccination.

Care must be taken over the process to ensure that the fluid does not 'roll off' the eye due to the surface tension of the droplets. Each bird should be held until it blinks after the droplet is applied and the whole process must not be rushed or birds will be missed.