Heat stress is one of the major causes of loss in animal production and reduced profitability of the business in tropical and sub tropical areas. Animals find it difficult to cope with heat stress, it doesn’t require any medication at all, rather proper welfare has to be put in place to palliate the effects of this threat.
When an animal is heat stressed, any farm animal, the paramount effect is the reduction in production. For any animal to be productive, it has to be free from any internal or external threat or stress.
Heat stress is one of such.
Heat stress in poultry.
Poultry production is a common livestock business around the world, it is practiced in different capacities, small, medium and commercial scale. As a poultry farmer, your goal is to manage the birds such that they produce optimally and increase productivity, hence, making profit from it. There are many factors that can deter this aim, some are known and easily detected while some are unaware. Some requires medications while some just need a proper welfare. These are the rudimentary knowledge a poultry farmer should always have in mind.
Heat stress impedes egg production and causes stunted growth in birds. When constructing a poultry house, the environmental condition of the site should be known. Tropical and sub tropical regions are known to be heat bearing, a farmer planning to erect a poultry structure in a tropical or sub tropical region should have a measure to control heat stress. Under supervision of the farmer, the houses provide everything birds need to maintain their welfare and performance, including protection from the weather.
High ambient temperatures can have a major impact on performance of commercial poultry. When they are coupled with high humidity, the combination can become critical. Therefore, there is a need to re-evaluate the management of poultry and equipment used in hot weather so that heat stress is minimized. Heat Stress does not only cause suffering and death in the birds, but also results in reduced or lost production that adversely affects the profit from the enterprise.
Birds are heat stressed when they find it difficult to achieve a balance between body heat production and body heat loss, this occurs at all ages and any poultry bird. Most times when birds are stressed, they pant. Panting is a normal response to heat but when birds are subjected to intense heat, such birds might die. Example in broiler birds, the body temperature of a broiler bird must remain very close to 41oc (degree) but if the body temperature rises more than 4oc (degree) above this, the bird will die. This is how dreadful heat stress can be. The poultry manager should be very observant to detect this before it leads to loss of birds.
How birds generate heat
Heat is generated from metabolic activities of the birds like egg production, growth and maintenance. The heat produced is affected by the birds body weight , specie of bird, type of bird, level of feed intake and quality of the feed taken. Aside from these factors of heat in birds, there are other external factors that induce heat in birds, such as roof and wall of the poultry house
How birds dissipate heat
It is essential for birds to dissipate heat in order to stay in the thermoneutral zone and free from stress. There are several ways birds loss heat but the most common methods are;
1. Radiation: Birds lose heat through radiation when the birds body temperature is higher than the surrounding temperature.
2. Conduction: This is the transfer of heat from bird’s body to it surrounding environment.
3. Convention: This is the loss of heat as a result of natural rise of warm air from a hot body.
4. Evaporation: This is otherwise known as panting, it occurs when the birds are under extreme heat. It is only effective if the humidity is not too high.
Signs of heat stress in birds.
When a bird is heat-stressed, it exhibits the following characteristics:
• Reduction in feed intake.
• Increase in water consumption.
• In a deep litter system, birds move away from themselves.
• Birds begin to pant.
• The skin colour becomes dark.
• Lift their wings away from their bodies to expose any areas of skin that have no feathers.
Effects of heat stress
As said earlier, heat stress is very detrimental to poultry business as it causes the following mishaps
• It reduces birds production because of the reduction in feed intake.
• It results in high mortality as a result of extreme heat stress.
How to prevent heat stress in birds.
Heat stress can be prevented by these means:
• The poultry house should be designed in a way that the longest side faces the direction of the wind. This will facilitate even ventilation, making the birds receive fresh air evenly. The house structure and ventilation should compliment each other to have maximum benefit. Ridge fans can be placed in high-efficiency chimneys to improve aeration in cases of extreme heat. The inflow of air is the best way to remove heat from poultry house, hence, proper ventilation in respect of the orientation of the poultry house should be achieved.
• Cool water must be served to rehydrate the birds because water is lost during panting. Cool water stimulates water intake and help to reduce the body temperature.
• Reducing the stock density of a pen is very essential because it creates more space and facilitates easy dissipation of heat.
• During heat-stress, feed consumption is reduced, it is best to adjust the diet of the birds to ensure adequate supply of nutrients.
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