Genetics and nutritional improvements in poultry husbandry have been extremely important to the efficiency of meat and egg production; however, the full genetic potential of poultry can’t be reached unless the proper environment is maintained in the house.The climate in poultry houses influences the well being and health of birds.In most developed countries, modern poultry houses rely upon electronic controllers. Through the use of controllers, it is possible to keep house temperatures within five degrees of the desired temperature regardless of outside temperature. This makes it possible to keep the birds comfortable so they are not diverting energy from growth to stay warm or cool.
Temperature and Relative Humidity and Air Composition inside Shed:
The highest and lowest critical temperature depend very much on: Age, Body weight, Housing system, Feeding level, Relative humidity, Air velocity and Health. The recommended temperatures are:
|First Day||1st week decrease||2nd week decrease||3rd week decrease||4th week decrease|
When outside temperatures are low, relative humidity in the house is low, which often results in dry dust circulating in the air within the house. If the relative humidity is too high, this may result in wet litter. The ideal relative humidity for poultry is 60-80%.
The gas Standard for European poultry Houses are:
|0||<2500 ppm = 0.25 vol%||<25 ppm = 0,0025 VOL%||0||0|
In order to maintain the above parameters to desired level, the environmentally constructed shed are designed as follows.
Construction of Shed:
Poultry houses are constructed with wood or steel trusses and supports. The houses are clear span structures from side wall to side wall. The trusses are engineered to support the weight of the roof without the need of support posts. The floor of the shed is compressed dirt that is covered with bedding material.For controlled-environment housing of layers, multi-tier cage systems are common. House dimensions are usually 40-50 ft wide, 400- 600 ft long with 8 ft high sidewalls.
Ceiling and Side Walls:
To improve ventilation and reduce heating costs, most houses are constructed with dropped ceilings.Insulation can dramatically affect the level of supplemental heat and ventilation requirements. Dropped ceilings protect the trusses and ceiling insulation by acting as a vapor barrier. Dropped ceilings reduce the ceiling surface area and allows for the installation of ceiling insulation to reduce heat gain in during hot weather and heat loss during cold weather. Modern houses are well insulated with blown in cellulose or fiber glass insulation.The effectiveness of insulation is measured by its R-value. Insulation values of at least R-21 and R-7 are recommended in the ceiling and walls,respectively.Houses are constructed with solid side walls which provide better insulation, reduce air leaks, provide better light control and allow the house to be heated more efficiently. The use of solid side walls provides a smooth surface compared to open sides walls with posts. This improves air speed during tunnel ventilation that will increase the cooling of birds next to the wall.
Heating systems include radiant brooders, pancake brooders, forced air furnaces and radiant tube heaters. Brooders and tube heaters project heat onto the floor. The hot air furnaces heat the air, which then heats the floor. Hot air is lighter than cold air. This can result in stratification with the air being warmer at the ceiling than at the floor. Circulation fans are often used to move hot air from the ceiling down to the floor. Paddle fans can also be used to mix air, but one should be careful to ensure that the chicks are not exposed to drafts.
Hot and Cold Weather Ventilation:
Ventilation system in a poultry house consists of fans, air inlets, evaporative cooling system and controller/thermostats. Houses are designed to deal with both cold and hot weather extremes.
During Cold weather:
Negative pressure ventilation is used to provide fresh air, remove moisture and minimize heat loss. Fans exhaust air out of the house creating a slight negative pressure inside the house. Fresh air is pulled into the house through air inlets installed either high on the house side wall or in the ceiling. The fresh air should be directed towards the roof to mix with warm air and then circulate throughout the shed. Distribution of inlets uniformly around the perimeter of the building, size of the fans and inlets are critical if all areas of the house are to be ventilated. The location of the fans and air inlets depends upon the width of the building. Fans should be placed in one side wall for buildings up to 40 feet wide. Buildings more than 50 feet wide need fans on both sidewalls. Air inlet size is critical to proper functioning of the ventilation system. The air inlet velocity must be high enough to ensure fresh air reaches all portions of the facility. However, the air velocity must not be so high that the birds are subject to draughts. Computer controlled system can be used to determine when the fans operate and for how long.
With Older Birds and in Hot Weather:
The incoming air is directed down towards the birds, and helps to keep them cool. Evaporation cooling pads can be placed in the air inlets to keep birds cool in hot weather. Tunnel ventilation is the most effective ventilation system for large houses in hot weather. Tunnel ventilation systems consists of fans at one end or middle of the house and larger air inlets at the opposite side. Evaporative cooling pads are located at the air inlets. When tunnel ventilation is not sufficient to cool the house, the evaporative cooling system is activated. Energy in the form of heat is used to evaporate water lowering the air temperature. Sometimes water will not evaporate which led to wet litter problems. This problem is corrected by moving the evaporative cooling system outside of the house.
Control of House Environment:
Almost all modern houses rely upon electronic controllers. Through the use of controllers, it is possible to keep house temperatures within five degrees of the desired temperature regardless of outside temperature. The controller monitors house environmental conditions and adjusts the heating, Humidity, ventilation and cooling equipment as necessary to keep temperatures constant. The controller operates equipment in the house including: brooders, fans, inlet machines, curtain machines, evaporative cooling systems and lights. Alarms are used to notify if there is loss of power or if the house internal temperature gets too high or too low in relation to the desired temperature or for other malfunction.