Various customization options are available for housing systems to improve the climate for broilers, with ventilation being one of the most important aspects.
Climate change is expected to increase heat stress in broilers, with increased ambient temperatures adversely affecting broiler production, reproduction, growth performance, health and welfare. Reduced energy consumption for heating will be compensated by increased energy consumption for cooling.
By 2050, global meat consumption is expected to increase to 455 million tonnes per year in response to expected population growth and a dietary shift towards higher protein foods. Broiler production is a major part of the world meat market and the broiler industry is expected to meet around 40% of the increased general demand for meat. Increasing and maintaining food production at this level will lead to increased energy consumption.
Climate change affects the need for resources for production
Conversely, there is growing concern about the impact of climate change on broiler production as the average temperature has been predicted to increase by 2-6°C by 2100, posing a serious challenge to sustainable broiler production. Climate change will further affect the type and sophistication of broiler housing systems and change the resource needs of broiler production. The economic and production efficiency of broilers is related to housing systems and climatic conditions. It is therefore necessary to adapt broiler housing systems to the prevailing and predicted climate change to minimize its adverse effects on the broiler industry.
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Impacts of climate change
Climate change is defined as long-term variations in climate patterns and temperature. The increase in global temperature, along with desertification and deforestation associated with climate change, will contribute to the burden of heat stress, which occurs especially in tropical regions and during summer. Heat stress promotes behavioral, physiological and biochemical changes in broilers, leading to economic losses. In addition, it will reduce water availability and increase the energy required for cooling, potentially compromising broiler production, reproduction, growth performance, health and welfare.
Running broiler houses at full capacity with uniformly sized flocks is a common practice that allows for more precise control of the microclimate inside the house and improves efficiency. Industrial broiler production involves the regulation of the indoor microclimate driven by the heat flows occurring inside the broiler house and the requirements of the broilers during their growth phases.
Heating, ventilation and air conditioning systems are used to regulate the temperature in the broiler hall. In winter, mechanical ventilation is used to circulate air and remove accumulated gases. In summer, ventilation and various forms of active cooling are used to keep the indoor temperature below a certain threshold. Evaporative cooling pads are the most common method of active cooling used when temperatures exceed 30°C for more than 2 to 3 hours.
Regulation of body temperature
Broilers have a limited ability to respond to temperature changes due to the absence of sweat glands. In their thermoneutral zone, they can tolerate a narrow temperature range of 18-24°C. In the thermoneutral zone, the body temperature of broilers is kept constant and the bird loses heat at a controlled rate without discomfort. Heat stress in broilers results in death or reduced weight gain, reduced production, reduced reproduction and reduced growth performance along with welfare threats. When the ambient temperature is high, broilers need to regulate their body temperature by breathing, resting, drinking water and limiting physical activity to balance heat production against heat loss and maintain a relatively constant body temperature.
Understanding heat stress
Heat stress occurs in broiler farms when the ambient temperature exceeds 25 °C, while high relative humidity can also alter broiler heat perception. The concept of heat stress or exposure to high ambient temperatures can be broadly divided into acute and chronic heat stress. Acute heat stress refers to exposure to very high temperature stress for a short period of time, with the main effect on broilers being increased mortality, often due to suffocation. Chronic heat stress refers to exposure to high temperature over a prolonged period of several weeks, resulting in reduced weight gain, reduced production, reduced reproduction and reduced growth performance, as well as impaired broiler welfare.
Broiler housing systems must provide adequate pen temperature and relative humidity plus optimal air circulation. In closed systems, temperature and humidity are fully controlled using foggers, tunnel fans, fans and mist pumps.
In addition, the orientation and sophistication of housing, walls, floors and roof types for broiler housing should be considered to minimize the adverse effects of increased environmental temperature:
Ventilation: The orientation of the housing units should allow cross ventilation. Low-wall structures with wire mesh provide cross ventilation, while high-wall structures keep heat inside.
Walls: Additionally, mud wall homes provide a cooler interior than brick walled housing units.
Roof style: Should provide proper ventilation with materials that allow heat transfer.
Flooring: Flooring type has also been shown to affect broiler temperature, for example wire mesh flooring reduces skin temperature and cloacal temperature as well as broiler respiration and heart rate compared to deep bedding flooring during the hot season.
Insulation: There may also be a point where evaporative cooling pads are not effective enough to cool broilers. Therefore, other innovative solutions may be required, such as the use of air conditioning units and increasing the level of barn insulation. However, there is an optimal level of insulation that depends on location and weather conditions.
In conclusion, climate change may lead to a reduction in energy needs for heating and an increase in energy and water needs for cooling in broiler houses. Various adaptation options are available for housing systems to improve the climate for broilers. However, only limited work has been done to understand the impact of climate change on broiler production, reproduction, growth performance, health and welfare.
These effects could create new risks for the sustainability of broiler production by changing resource requirements for temperature control in broiler houses. Government agencies and NGOs should conduct further research to better understand these factors in climate change mitigation and adaptation, as well as resilience strategies to minimize the adverse effects of climate change.