(a) (i) Temperature: (1) High temperature causes a reduction in feed intake low temperature encourages more feed intake. (2) High temperature reduces spermatogenesis and libido in males. (3) High temperature causes heat stress and reduced activity. (4) It may result in death of birds particularly chicks and layers. (5) It increases water intake in hot II weather and reduces water intake in cold weather. (6) It is necessary for incubation of eggs; (7) It lowers egg production. (8) Egg storage period is reduced under high temperature. (9) High temperature reduces hatchability.
(ii) Control of heat temperatures (1) introduce fans or air conditioners, (2) provide enough windows or opening for ventilation; (3) cover windows with cloth materials to conserve heat; (4) provide vents at the roof tops; (5) use poor conductors of heat for roofing sheet /sun reflecting sheets or paint roof white. Pens should also have ceiling boards under the roof; (6) use room heaters or lanterns to warm buildings when it is cold, (7) During construction orient open parts of buildings away from direct solar radiation (East-west direction)
(b) Relative Humidity (i) is very important in incubation. (ii) High humidity compounds heat stress. (iii) Low humidity induces rapid water loss from bird's body and thus increases their water intake. (iv) High humidity encourages the spread of diseases. (v) High humidity causes feed to go mouldy. Control of Humidity: (i) fixing humidifyers or open trays filled with water to increase humidity. (ii) Allowing free ventilation when the humidity is high. (iii) Avoidance of spilling of water in poultry houses to reduce humidity/dampness.
(c) Light: (i) Controls egg laying in hens. (ii) Duration of lighting controls time spent at feeding which regulates growth and the rate of feathering. (iii) Direct light of high intensity causes stress to the eyes_(iv) Bright light makes the birds active. (v) Light makes objects visible. Control of light: (i) In short daylight, provide extra illumination. (ii) A reasonable part of the walls should be made up of wire mesh or glass to promote lighting. (iii) Cover up windows with dark cloth to reduce light intensity.