This article first appeared on Just Agric website.
Heat stress is one of the major causes of loss in livestock production; it reduces the profitability of the business in tropical and sub-tropical areas. Poultry birds 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 a poultry chicken is heat stressed or any livestock, the paramount effect is the reduction in production. For any livestock to be productive, it has to be free from any internal or external threat or stress. Heat stress is one of such.
Overview of heat stress in poultry birds
As a poultry farmer, your goal is to manage the chickens such that they produce optimally and increase productivity, hence, making a profit from it.
There are many factors that can deter this aim, some are known and easily detected while some are obscure. Some require medications while some just need 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 laying chickens. 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 contingency measures to control heat stress.
Under the supervision of the farmer, the houses provide everything the chickens need to maintain their welfare and performance, including protection from the weather.
High ambient temperatures can have a major impact on the 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 farm and equipment used in hot weather so that heat stress is minimized.
Heat stress does not only cause suffering and death in the chickens but also results in reduced or lost production that adversely affects the profit from the enterprise.
Chickens 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 chicken. Most times when chickens are stressed, they pant.
Panting is a normal response to heat but when chickens are subjected to intense heat, the chickens may die. An example is broiler chickens, the body temperature of a broiler chicken must remain very close to 41oC but if the body temperature rises more than 4oC above this, the chicken will die. This is how dreadful heat stress could be.
How chickens generate heat
Heat is generated from metabolic activities of the chickens like egg production, growth, and maintenance. The heat produced is affected by the chicken’s body weight, breed of chicken, type of chicken, level of feed intake and quality of the feed taken. Aside from these factors of heat in chickens, there are other external factors that induce heat in chickens, such as roof and wall of the poultry house.
How chickens dissipate heat
It is essential for chickens to dissipate heat in order to stay in the thermoneutral zone and free from stress. There are several ways chickens dissipate heat but the most common methods are;
- Radiation: Chickens loose heat through radiation when the chicken’s body temperature is higher than the surrounding temperature.
- Conduction: This is the transfer of heat from the chicken’s body to it surrounding environment.
- Convention: This is the loss of heat as a result of the natural rise of warm air from a hot body.
- Evaporation: This is otherwise known as panting, it occurs when the chickens are under extreme heat. It is only effective if the humidity is not too high.
Signs of heat stress in chickens.
When a chicken is heat-stressed, it exhibits the following characteristics:
- Reduction in feed intake.
- Increase in water consumption.
- In a deep litter system, chickens move away from themselves.
- Chickens pant.
- The skin color becomes dark.
- Lift their wings away from their bodies to expose any areas of skin that have no feathers.
Effects of heat stress on chicken
As said earlier, heat stress is very detrimental to poultry business as it causes the following mishaps
- It reduces chicken’s 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 chicken.
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 chickens receive fresh air evenly. The house structure and ventilation should complement each other to have maximum benefit. Ridge fans can be placed in high-efficiency chimneys to improve aeration in cases of extreme heat.
- Cool water must be served to re-hydrate the chickens 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 chickens to ensure an adequate supply of nutrients
As a poultry manager, you should be very observant to detect this before it leads to loss of chickens.
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