Traditional ventilation systems aim to minimise heat loss while preventing the build-up of excessive CO2 and humidity, which require the birds to consume more feed to achieve the same weight. This compromise has to be adjusted as the birds get older and ought to be, but is not always, adjusted to account for seasonal changes in ambient temperature and humidity.
There are many purposes for ventilation:
- Supply oxygen-laden fresh air
- Cooling: removal of heat released during respiration and activity, and also the solar gain through the structure, particularly in the summer.
- Drying: remove moisture from the air (released during respiration or evaporating moisture in the droppings). If the litter is allowed to get wet then the production of ammonia will increase.
- Remove harmful gases (carbon dioxide released during breathing or ammonia created by microbes operating on water in the litter).
- Remove dust particles suspended in the air from the skin of the birds.
- Dilute disease-causing organisms in the air.
As can be seen, greater ventilation has many benefits but requires the grower to burn more propane.
As margins are tight, profitability may depend on how well individual farm managers respond daily to bird appearance, weather and house conditions while containing their propane costs.
Using a cheap source of fuel for heating houses offers growers to change over from operating minimum ventilation rates to optimum ventilation rates.