Security on chicken farms should guard your flock against more than just theft. The invisible enemy, disease, can cause extreme losses on your chicken farm.

Certain biosecurity measures can be taken to ensure that your chickens are kept safe from disease. Biosecurity is a set of management measures that collectively reduce the chances of introducing or spreading disease-causing organisms onto and between sites.

Most infectious agents enter the chicken via the beak while eating, drinking, or cleaning its feathers, or while breathing. Other infectious agents can infect a wounded chicken. The agent then multiplies within the chicken and may spread, causing damage to certain organs resulting in clinical signs. After multiplication, some of the infectious agents leave the chicken through droppings, in discharges from lesions, in its breath, or even on dropped feathers. When other chickens come into contact with these contaminated items, then they too may get infected.

Infectious agents can survive outside the chicken for varying periods. Worm eggs and coccidia, for example, can survive for several months in the environment, while some other infectious agents are easily destroyed by sunlight, disinfectants, or heat.

In the spreading of diseases caused by agents that are easily destroyed, direct contact between the chicken and agents is necessary. Infectious agents that can survive for a certain period in the environment can also be spread via persons, animals and materials that might carry the agent. The infectious agent might be carried with small traces of droppings on shoes, or in the dust or small feathers attached to any rough surface, on the eggshell or any part of a dead chicken.

Once infectious agents enter the chicken, the chicken does not get sick immediately. It usually takes some days for the bird to show signs of illness. This period is referred to as the ‘incubation period’. During this period, the bird does not show any signs of disease, but the number of infectious organisms inside it increases rapidly, and some organisms may leave the bird when it breathes or drinks or passes droppings. This means that the agents causing an infectious disease can be spreading even before clinical signs of the disease are manifested. Some infectious diseases can also be spread vertically, that is from the hen to her offspring, via the eggs. To date, vertically transmitted diseases are more of a problem in commercial poultry enterprises.

Common bio-security measures:

Location

Avoid locations close to existing chicken farms (between farms 500 m to 1 km); use prevailing wind directions when planning to minimise risk of airborne infection.

All in – all out

Reduce build-up of disease-causing organisms by breaking the rearing cycle for different ages.

Litter disposal

Remove used litter and properly disinfect and dispose of it.

Site security

Reduce possible introduction of infection to premises by personnel moving between houses and flocks, equipment, and other innate objects.

This article is published with full recognition to Kenya Agricultural Research Institute who first published it in the Indigenous Chicken Farming Training Manual.