Understanding your chicken's respiratory system for good welfare

Victoria Roberts BVSc MRCVS looks at why ventilation is essential to your poultry's health

- By Victoria Roberts BVSc MRCVS

The respiratory system in chickens (and other birds) is very different from mammals. Chicken lungs do not move when they breathe but the air is pushed through the fixed lungs by the several airsacs around the body. This is a more efficient method of obtaining oxygen than the mammalian system since the birds need higher oxygen levels in order to fly successfully, together with ways of reducing weight such as hollow bones and solid urates (no bladder needed), the bird form of urine. It also means that mucus in the lungs which helps to move pathogens away has a different system of working, unlike mammalian coughing. The chicken mucus is transported up the trachea and then either swallowed or flicked out of the mouth. This mucus transportation is done by small hairs in the trachea called cilia. Cilia are paralysed by ammonia fumes and as chickens do most of their defecating at night, most droppings are in the hut giving off ammonia which rises up past the