Farm hygiene and biosecurity practices are implemented at both breeder and broiler farms to reduce the risk of disease agents moving on to farms from outside sources (eg wild bird populations or from other farms), the movement of disease agents between sheds on the same farm, carry over of disease agents from one batch to the next in the shed environment, and carry over of disease agents from breeding flocks to their progeny via the egg. Farmers take a range of precautions to prevent entry of diseases onto broiler farms.

Risk from human movement

As people are considered to be one of the biggest risks insofar as carrying poultry diseases onto chicken farms, particularly on their footwear, clothing, hands and even vehicles, growers take a number of measures to minimise the risks they pose. These may include:

1.     Signage and gates at access points to the farm to discourage / prevent unauthorised entry to the farm

2.     Visitors and service providers to the farm must wear overalls and boots provided by the farmer;

3.     Provision of foot washing baths at the entrance of each shed for disinfection of footwear prior to shed entry

4.     Vehicle movements onto the farm are minimised, and vehicles or equipment that may have visited another farm may be required to be washed down before entry

5.     Where people or vehicles must move between farms on the same day without a thorough disinfection between farm visits, movements are scheduled such that the youngest flocks are visited first and the oldest last.

As wild birds can carry some diseases onto the farm, a number of measures are taken to minimise the possibility of wild birds (or their droppings) coming in contact with the chicken flock. These measures include:

·        wire netting the sheds so that they are bird proof;

·        farmers (and their employees) are not allowed to keep any birds as pets;

·        wild birds are discouraged from visiting the farm site, by ensuring that there is no spilled feed left lying around and, where practical, no dams that attract water birds;

·        where the water that supplies the shed could be contaminated by wild birds eg dam or river water, it must be sanitised.

Disease prevention

Farmers have a documented pest control program to reduce the risk of diseases being carried on to the farm by rodents. Strict records are kept by the farmer of the chickens’ health, growth and behaviour, so that any emerging disease problem is rapidly identified and acted upon.

Disease prevention is an essential strategy for poultry producers. It is much more beneficial to the birds and to the commercial poultry producer to prevent disease from occurring rather than to rely on treatment.

General husbandry

Healthy, unstressed birds have an active metabolism and effective immune system to protect them against disease. Feeding birds appropriately with a nutritionally balanced diet, maintaining a comfortable living environment and minimising fear and anxiety in the birds will help the bird’s natural protective mechanisms to function optimally.

Breeding stock
(Source: Aust. Chicken Meat Fed.)

Stock selection

Different genetic lines of poultry may vary in their ability to resist or recover from some diseases. The choice of genetic lines resistant to disease problems that have been known to occur in a particular poultry operation can substantially reduce the costs of disease and other disease prevention techniques.

Vaccination

Vaccines aid in preventing disease by stimulating the bird’s immune system in such a way that it enhances the immune response when the bird is subsequently exposed to a pathogen (or disease-causing organism). Classically, vaccines have either contained a small live dose of a weak form of the pathogen or a larger dose of a killed preparation of the disease-causing organism. The weak forms of pathogens used in live vaccines can either be naturally occurring or can be developed in a laboratory. If they have been developed they are called attenuated vaccines. Live vaccines tend to give longer immunity than killed vaccines because the live organism can colonise and survive in the host for some time and stimulate a longer and more effective immune response.

New technologies are leading to improved methods of developing vaccines. These include more efficient methods for identifying the ways organisms cause disease and stimulate an immune response in the host, as well as highly specific and effective attenuation procedures.