On-farm ventilation systems is a key factor to consider in poultry production facilities. Maintaining adequate temperature and aeration of the houses is essential to ensure animal welfare and economic performance of the farm.

The role of ventilation

In poultry farming (eggs and especially meat producers) birds need to consume a large amount of good quality feed to develop the metabolic processes required by the environment and their organisms (growth, posture, weight gain, etc.). Besides, other factors are involved in this process: population density, geographic location and age of the birds, among others.

The metabolic processes increase humidity levels. Birds eliminate water through respiration and feces and the moisture is accumulated in the environment and needs to be removed through ventilation. Also, humidity increases the thermal sensation of the birds.

On the other hand, in this metabolic process, a large amount of heat is released to the environment, which we measure through temperature. Because birds cannot sweat, they eliminate the excess of heat through breathing, vigorous flapping, and panting.

Ventilation helps to eliminate excess of heat and humidity from the sheds where the birds are housed, generating comfort and welfare.

Birds eliminate body heat in 4 ways, which are the ones that increase the temperature of the shed, these are:

1. Convection: the heat of the bird is eliminated by air movement
2. Conduction: heat is transferred by direct contact
3. Radiation: the bird emits electromagnetic waves of heat
4. Evaporation: by breathing, the bird removes heat through water

Having a ventilation system and a controlled poultry environment, provide some benefits:

1. 1. Correct balance of the gases that participate in the metabolism of the birds: good availability of oxygen breathed, and elimination of gases such as Carbon Dioxide CO₂ and ammonia NH₃.
   2. Avoid heat stress that leads to less food consumption and, in some cases, death due to heat shock in populations.
   3. Lower costs associated with energy demand in inefficient systems that cannot control the temperature.
   4. Reduction of the humidity of the litter, which avoids the appearance of problems in the leg of the birds.

Therefore, ventilation mechanisms must exist in a controlled environment to maintain the ideal parameters within the shed of our poultry production.

Ventilation basics

Before mentioning ventilation, some concepts should be clarified as they are mentioned commonly.

• Controlled environment: it is an environment or accommodation whose physical configuration (that is how it is built) allows the manipulation and control of the conditions such as temperature, humidity, airflow, the quantity of gases, among others. To be optimal it must be sealed; This is one of the most common shortcomings.
• Fan: it is a machine that facilitates the movement of ambient air into the shed, to mix the outside air with the inside and thus balance the temperature and humidity.
• Extractor: it is a machine that facilitates the expulsion of the air inside the shed to the outside environment again after it has circulated throughout the poultry house.
• Minimum ventilation: it is an expression used to refer to the ventilation that a poultry farm needs to maintain the environment of the houses in optimal and balanced conditions

Types of pressure in ventilation

• Negative pressure
  

  It is the most common way in poultry with controlled environments to mobilize the air from the houses. It consists of the entry of air through openings in ceilings and walls, mobilized by fans. This air inside the poultry house circulates and heats up around the fowls. This warm air is then expelled back into the environment by high-powered extractors.

• Neutral pressure
  

  The system is similar to the previous one but requires more fans. It is called this way because both, the pressure inside the house and the outside, are the same all the time. This system requires less energy for the fans that move the air.

Ventilation systems

• Natural ventilation
  

  It is a ventilation system used in uncontrolled poultry environments. It is common in small-scale productions. It consists of ventilation directly with ambient air, controlling its intensity with curtains. It is useful in some regions, but in others, it can be difficult to apply, as it has been associated with high levels of gases in the shed air, such as NH₃ ammonia. (Osorio, R., 2016).

• Tunnel system
  

  It is the most widely used ventilation system in large-scale poultry productions, in which they have controlled environments in their sheds. The tunnel system can have variations depending on how the shed is built, its layout, its orientation, its capacity, among other things. The movement of air into the house is controlled by the pressure models that we reviewed above. It works, first, with the air inlet through some specific openings of the poultry house. The air then passes between the fowls to balance their temperature with the air inside. Finally, the air is expelled at the opposite end to where it entered, to reach the outside environment again.

General recommendations

• Air inlet: at no time should the air inlet be directly on the birds because it will generate stress. It must inlet in the upper part of the shed to mix with the air inside the house.
• Location of the house: before building a poultry house, factors, such as the cardinal position, must be taken into account to avoid direct sunlight on the birds and airflows that may favor or complicate the ventilation of our system.
• Environmental gas meters: it is important to keep a record of the quantity of gases such as Carbon Dioxide CO₂, Carbon Monoxide CO, Ammonia NH₃, among others, to monitor the balance of the circulating air.
• Technical and professional assistance: advice is necessary to establish exact parameters such as circulating airspeed, types of fans and extractors, number of air inlets, and their position, among others.

Conclusions

Poultry farming is one of the most efficient sectors of animal production, and part of these achievements have been due to the implementation of technologies such as ventilation in controlled environments. Ensuring a balanced environment and optimal conditions for the birds is translated into improved intensive production and long-term cost reduction. Therefore, knowing how ventilation systems work and what benefits they have is a crucial element for the development of any poultry farm.

References:

– Aviagen, 2009. Manejo del ambiente en el galĂłn de pollo de engorde. Disponible en lĂ­nea en: http://es.aviagen.com/assets/Tech_Center/BB_Foreign_Language_Docs/Spanish_TechDocs/Aviagen-Manejo-Ambiente-Galpn-Pollo-Engorde-2009.pdf
– College of Agriculture, Food and Environment, S. f. Poultry Production Manual. University of Kentucky. Disponible en lĂ­nea en: https://afs.ca.uky.edu/poultry/chapter-7-mechanical-ventilation-systems
– Czarick, M., 2019. Evaluation of the Combined Effects of Air Movement and Reduced House Relative Humidity on Bird Health and Welfare in the Early Phase of Commercial Broiler Production- Disponible en lĂ­nea en: https://www.uspoultry.org/research/resproj/PROJ_705.ht
– Alojamiento y manejo de aves de corral en paĂ­ses en desarrollo. Disponible en lĂ­nea en: http://www.fao.org/3/a-al734s.pdf
– Guerra, R. S. f. Los fundamentos de ventilaciĂłn en casetas avĂ­colas. Symposium cientĂ­fico de avicultura. Disponible en lĂ­nea en: https://www.wpsa-aeca.es/aeca_imgs_docs/11230_fundamentos%20de%20ventilacion%20en%20casetas%20avicolas.pdf
– Osorio, R., Tinoco, I. F., Osorio, J. A., Souza, C. D. F., Coelho, D. J. D. R., & Sousa, F. C. D. (2016). Calidad del aire en galpĂłn avĂ­cola con ventilaciĂłn natural durante la fase de pollitos. Revista Brasileira de Engenharia AgrĂ­cola e Ambiental, 20(7), 660-665.
– Rey, M., 2011. AplicaciĂłn de los conceptos de ventilaciĂłn. Jornadas Prof. de Avicultura. Lleida, 23-27. Disponible en lĂ­nea en: https://seleccionesavicolas.com/pdf-files/2012/2/6527-aplicacion-de-los-conceptos-de-ventilacion.pdf
– USDA, 2013. Poultry industry manual. Disponible en lĂ­nea en: https://www.aphis.usda.gov/animal_health/emergency_management/downloads/documents_manuals/poultry_ind_manual.pdf
– Vostermans Ventilation, 2020. ÂżCĂłmo determino el sistema de ventilaciĂłn ideal para mi gallinero? Disponible en lĂ­nea en: https://www.vostermans.com/es/ventilation/blog/como-determino-el-sistema-de-ventilacion-ideal-para-mi-gallinero

Figure 1. image taken from pixabay licensed by pixabay for free commercial use.
Figure 2. image taken from https://www.geograph.org.uk/photo/2327404 copyright evelyn smiak licensed for cc reuse.
Figure 3. image adapted from: college of agriculture, food and environment, s. f. poultry production manual. university of kentucky. available online at: https://afs.ca.uky.edu/poultry/chapter-7-mechanical-ventilation-systems