Agricultural Structures and Environmental Control 3(2+1)

LESSON 11. Fundamental Requirements of a Poultry house

1.2 Humidity

When the temperature is between 32 and 45°F, the humidity should be kept below 85%.  For higher temperatures the humidity should be kept below 75%. High humidities at high temperatures create undesirable conditions for the  hens and result in excessive condensation in the building.

1.3 Air and its movement

A properly designed ventilation system should provide an adequate supply of fresh air for the birds and remove the products of respiration, the excess heat produced and the moisture from the breath and litter, all without causing undesirable drafts. A laying hen will produce 40-50 BTU total heat per hour of which 25-30 BTU will be sensible heat. The moisture which must be removed by ventilation will amount to @ 1/3^rd lb of water per less in a day. The ventilation rate and amount of insulation should be balanced in design.  An average of 2/3^rd cubic foot of air/min. for each sq. feet of floor area is required. The exhaust duct size or fan capacity can be easily determined from the computed ventilation rate. Various types of ventilation in inlets have been used successfully in poultry laying houses. No inlet should be placed closer to any flue or exhaust fan.

1.4 Light

Natural delight well distributed throughout the house provides the necessary lighting for chores and for the hens to feed. The recommended window area ranges from 6-25% of the floor area for ordinary window glass. This area can be considerably increased in solar-oriented houses with insulating glass. The windows should be so distributed that 75% of the window area extends continuously across the front of the house. Artificial lighting is new commercially used during the winter season to extend the length of day for increased egg production. A 12-14 hours length of day is recommended. The light requirement is the equivalent of the 40 watt lamp hung at 6 feet above each 200 sq. feet of floor area.

1.5 Heat and moisture production inside poultry

Excessive moisture in farm buildings can cause considerable damage. Apart from spoiling the appearance where moisture collects on walls and leaves stains, considerable damage can result from rotting of wood members by moisture; moisture in walls reduces insulation value.

One of the primary sources of moisture in a building for housing poultry is that which has been given off to the air in the form of vapour by the birds.

Condensation:  The most obvious moisture is that which condenses on the inside surfaces of the walls or windows because it is visible.  Condensation will occur on any surface which in below the dew point temperature of the air surrounding it.  The air in close contact with the surface is cooled, thus increasing its relative humidity.  When cooled to the saturation point, any further cooling results in condensation.

The inside surface of walls of buildings are cooler than the inside air whenever the outside of the wall is exposed to a lower outside temperature.  To determine whether the condensation will occur, the inside surface temperature must be computed to determine whether it is below the dew point of the inside dir.

The temperature of the inside surface may be computed by the formula.

Sanitation for Poultry

Cleanliness and sanitation are of extreme importance in carrying for poultry.  Hens are subject to numerous diseases and insect infestations.  Although sanitation is principally a management consideration, certain structural practices can facilitate the maintenance of sanitary conditions.  Providing a suitable environment and cleaning the litter inside the house leed to sanitation.

The construction of the house with smooth surfaces can reduce the accumulation of dirt and facilitate cleaning and disinfecting.  Equipments used in the poultry house, such as waterers, nests and feeders, should be of a type that can easily be cleaned out and disinfected.