Poultry Barn Ventilation
Eastern Ontario Poultry Conference
October 17th, 2007
Poultry barn ventilation has a number of functions including the
supply of fresh air to birds, the maintenance of a desired temperature
in the poultry barn, the removal of excessive humidity as well as
the elimination of odours and other gases. Water vapour resulting
from the respiration of birds produces humidity. Heaters in the
poultry barn also produce moisture. Furthermore, both the birds
and heaters in the barn produce CO2.
Odour in the poultry barn can be caused by inadequate ventilation.
Poor air quality can cause an increase in respiratory problems,
potential blindness, increased incidence of breast blisters and
cellulitis as well as lower profitability.
Minimal air renewal is required in livestock barns. This is referred
to as minimum ventilation. The objective of minimum ventilation
is to exhaust sufficient air to maintain a relative humidity level
of between 55 % and 65 % (depending on the age of the birds) as
well as to maintain ammonia gas levels less than 20 PPM and carbon
dioxide gas levels less than 5000 PPM.
The location of air inlets is crucial. As cold air is heavier than
warm air, cold air will fall to floor level and will not climb up
sloping ceilings. The location of air inlets should at the top of
the sidewall and they should be automatically controlled. Static
pressure of 0.06 to 0.08 should be maintained inside the barn during
the cold weather. During the warm weather season, a static pressure
of 0.03 to 0.06 should be maintained inside the barn. Cold air does
not hold much moisture but generally has a high relative humidity.
Every 10 C temperature rise doubles the moisture holding capacity
of the air. Supplemental heating is often required to maintain both
the desired room temperature and still allow required air exchange
for good air quality.
Certain preparations are required for the cold season. Large summer
fans should be covered with interior insulated panels. All load-out
and clean-out must be weather-stripped and clamped tight shut. The
effective length of air inlet available for minimum ventilation
should be reduced.
Internal air circulation is also a very important factor. All poultry
barns must have internal air circulation to ensure the distribution
of fresh air, to distribute supplemental heat, to help eliminate
temperature differentials and temperature stratification. In addition,
internal air circulation solves the problem of insufficient static
pressure in cold weather with small birds, helps to dissipate CO2
near the floor and carries a well mixed sample of room air past
each operating fan for extraction.
Ventilation controls are at the heart of every ventilation and
heating system. They must be managed properly and if new controls
are not well understood by barn operators, plenty of coaching and
practice time will be required.