Dr.R.Selvakkumar., M.V.Sc., Ph.D., Instructional Livestock Farm Complex
Veterinary College and Research Institute – Tirunelveli – 627 358 Tamil Nadu
Environment is defined as the combination of biological and physiological factor which affect or else have an impact on animals and humans. When compare with other season, summer is the challenging period for poultry birds and poultry farmers. The extreme climatic condition prevailing during summer can affect the performance of the birds either directly or indirectly. Poultry are homeothermic ﴾constant body temperature﴿ in nature, and they must maintain their body temperature with in a constant range and during extreme temperature, the face problem to keeping their body cool and maintaining homoeothermic body temperature. Extreme environmental temperature will results in heat Stress and this will end in reduced or loss of production in birds and hence it adversely affects the profit from the enterprise. In this juncture, managemental decisions play a crucial role to save the farm from loss of production. This article discusses some of the key principles involved in reducing the summer heat stress in poultry houses.
Body Heat Balance :
Heat is produced by physiological processes (metabolism) which include maintenance, growth and egg production. This heat production is affected by many parameters which includes breed, species, body weight, level of production, feed intake and feed quality. Apart from the above, poorly designed roof and walls also adding heat to the poultry house. This altogether will put the birds in to the discomfort zone and they are forced to evaporate the excess body heat to save themselves. Since, accumulation of heat inside the house will produce detrimental effect on birds. So, it is must to remove the accumulated heat in order to maintain the birds in an ideal environment. This can be achieved by effective housing, feeding, watering and other managemental practices.
Heat loss by birds :
To save themselves from intense heat, birds will lost its body heat by many ways namely
Radiation : If the surrounding surface temperature is lesser than the birds body temperature, the heat will be lost by radiation.
Convection : Heat loss will occur from the natural rise of warm air from around a hot body.
Conduction : If the contact surface is cooler than the bird’s body temperature, heat will be transferred from the birds body to the contact surface.
Evaporation : If above methods are unable to bring the bird in to the safe zone, the birds must use evaporative heat loss or panting.
Behavioral response by birds to heat stress
- Isolate themselves from other birds.
- Birds are in search of cooler surface and moving air
- Expose the feather less area by lift their wings away from the body which will help to reduce the insulation.
- Reduction of physical activity
- Reduced feed intake and increased water consumption
Poor heat stress management will results in poor layer production performance and reduce the growth performance of broilers. Heat stress can be managed by altering the macro- and micro-environments of the poultry house. This can be achieved by following ways
- Housing management
- Feeding and watering management
- Other general management
- The poultry house site, orientation of the buildings, insulation capacity of the building , roof overhang, equipment design and other fittings will affect the inside temperature of the poultry house.
- East – west direction of the long axis of the poultry house and sufficient roof overhang (1.5 meters) will prevent the direct sun light in to the poultry house.
- Shiny surface can reflect more solar radiation than a rusty or dark roof. Selection of roof with reflective characters and painting of roof with reflective covering can reduce the inside house temperature.
- Providing adequate ventilation in order to eliminate hot air and entry of air flow in to the house.
- Sprinklers onto the roof and install foggers inside the house will helpful to bring down the temperature inside the house.
- Use of temporary side curtains to avoid direct hot wind.
- Raising trees around the poultry farm will help to reduce radiant heat.
- Increasing the speed of air at bird level with extra fans can useful to increase the rate of convection loss from the bird during hot weather.
- Good ventilation play a vital role in heat stress management. A good ventilation system will removes moisture laden air brings fresh outside air.
Feed and water management
During hot weather, feed intake in birds are reduced in order to avoid excess heat production. The fact will helpful to manage the heat stress but will affect the production performance of the birds by reduced feed intake. So, care must be taken to supplement the required nutrients by providing energy and other nutrient rich diet. Dietary adjustments will helpful to maintain a good supply of nutrients.
Feed the birds at the time of day when feed consumption is highest. Feed consumption will be higher during early morning and late evening.
Panting during hot weather will leads to higher loss of water. So, birds must always have access to plenty of cool water.
Other managemental practices
Handling (Catching, loading and transportation) of birds during the hot hours of the day should be avoided. Because, handling the heat stressed birds will aggravate the condition. Cooler part of the days are opt for such operation.
Stocking densities in the poultry house should be adjusted according to building design and temperature.
During transport, the vehicle should not be left in direct sun light and crates are stacked in such a way to allow sufficient ventilation.
We should ensure that all the staffs and workers of the poultry farm are able to recognize the sign of heat stress in birds and also know the remedial measures to manage the heat stress in birds.