Farmers top image

Help your birds get fresh air to thrive

By Dr Watson Messo
Wycliffe Lwangu and Mogan Abukose feed their improved kienyeji chicken at Maji Mazuri village in Lugari. [Duncan Ocholla, Standard] 

Unlike human beings who have well developed lungs and a chest cavity, chickens have small fixed lungs and air sacs and air flows in one direction. This God-given ability to birds help them a lot during flights and birds can still take in oxygen when they are breathing out.

However, for commercial birds kept in-doors, we need to keep minimum ventilation in the units and make the air conducive for growth, maintenance and production. If they cannot fly away into fresh skyways, we must bring to them fresh air full of oxygen and remove stale air full of carbon dioxide.

Hot summer period

During this hot summer period, farmers keeping large flocks of birds need to watch out the potential danger of poor air quality in the environment of their flocks.

There is need to follow the following steps to manage excessive ammonia, carbon dioxide, carbon monoxide and dust in the chicken house.

Dealing with excessive ammonia

Ammonia essentially is a by-product of breakdown of uric acid into urea. Uric acid is produced by the chicken kidneys and are the white deposits on the top of the feacal droppings. High ammonia is produced when there is excessive wet manure, in cases of poor ventilation, high relative humidity, poor diet and in sick birds with excessive diarrhoea and water loss.

How it affects the birds

Excessive ammonia in the broiler poultry shed will reduce the average daily weight gain, feed to meat conversion efficiency. In other words, birds will eat more feed to gain a kilogram of live weight. For laying flocks, in extreme cases of poor ventilation, there will be drop in egg production.

In severe cases, respiratory diseases may set in and birds will start to experience symptoms and signs like snicking, tracheal rales, inflammation of the air sacs, red eyes and may succumb to pneumonia. In complicated cases, birds may lose eyesight, develop lameness due to ammonia burns.

Excess carbon dioxide

Carbon dioxide is mainly produced by the birds during metabolism and released into the air during expiration. It is also produced during brooding when oxygen is consumed during burning of charcoal and CO2 is released especially during the first 14 days of life. Farmers are advised not to use polythene bags as curtains during brooding and must allow minimum ventilation in the house to avoid instant death due to excess CO2.

Carbon monoxide poisoning

This is by far the most poisonous gas encountered in a poultry shed and will kill in minutes. The gas is produced where there is insufficient burning in a furnace during brooding and is picked up by hemoglobin in the blood stream instead of oxygen causing CO toxicity. It is due to poor maintenance of heating equipment. The clinical signs include uneasiness, stupor, drowsiness, labored breathing, loss of co-ordination and tissues appear pink.

If you are using gas brooding, avoid yellow flames, make sure brooders are well maintained, provide enough ventilation to reduce the impact. It is more common in cold environments where farmers are trying to conserve heat by closing brooding rooms air-tight.


Excessive dust come from feathers, skin, litter, manure and environment. If largely inhaled by birds, dust will destroy the mucosal linings of the respiratory tracks creating an environment conducive to proliferation of viruses, bacteria, mycoplasma and moulds.

It is associated with inflammation of the air sacs, the third eyelids, inflammation of the skin. In the long run the birds will show poor growth rates, low feed conversion or efficiencies and increased mortality.

Ensure the poultry unit is fully ventilated by opening the curtains and if the air movement is still, consider use of extraction fans to move the fresh air in and stale air out.

Birds welfare

Keep optimal bird density in the units, for broilers, never go beyond 17 birds per metre square in open sided units and for layers keep the density at 500cm2 per hen

[The writer is the head vet at Kenchic, you can reach him on]      

Popular Posts

Sister Linet Kwena feeds chicken.

Related Post

Dalton Nyabundi -
Dr Watson Messo -
© Copyright 2019 - The Standard Group PLC