Before understanding how to install ventilation fans in chicken houses, we first need to understand the purpose of the chickens, their growth stages, and the farming methods. This directly determines the design of the ventilation system, the type of fans, their installation positions, and quantity.

I. Classification by Purpose and Production Type of Chickens

1.Laying Hens (Specialized in Producing Table Eggs)

Mainstream Systems: Globally, cage farming remains the most efficient method.

• Traditional Battery Cages: Still used in many countries but banned or strictly restricted in the EU and other regions due to limited space and restricted natural behaviors.
• Enriched/Modified Cages: The current mainstream upgrade direction. Larger than traditional cages, they must be equipped with perches, nesting boxes, litter areas, and claw grinders to meet the basic behavioral needs of chickens. Mandatory in the EU.
• Cage-Free Systems:

1. Aviary/Free-Range Systems: Chickens move freely within the entire house, equipped with multi-tiered perches and automatic nesting boxes.
2. Barn Systems: Similar to aviary systems but with a more enriched environment.
3. Free-Range Systems: Based on barn systems, chickens have regular access to outdoor areas.

2.Broilers (Specialized in Producing Chicken Meat)

Mainstream Systems: Almost exclusively use large-scale floor farming.

• Method: Tens of thousands of chickens are raised in enclosed or open-sided houses with litter (e.g., wood shavings, rice hulls). They move freely within the house to eat and drink throughout their growth cycle (typically 5-7 weeks).
• Reason: Broilers grow extremely fast, and their bones are relatively fragile. Cage farming can easily cause breast and leg issues. Floor farming is more conducive to their growth and health management.
• Upgrade Trend: Higher-welfare farming models such as "slow-growing" breeds, increased natural light, and the provision of perches and enrichments (e.g., straw bales) are emerging.

3.Breeding Chickens (Producing Hatching Eggs for Broilers or Layers)

• Systems: Specialized, managed in stages.
• Rearing Period: Typically floor-reared to allow roosters and hens to interact and establish a natural social hierarchy.
• Laying Period: To efficiently collect clean hatching eggs and perform artificial insemination, hens are usually kept in specialized breeding cages (colony cages), each housing 10-20 birds. Roosters may be kept in individual cages for semen collection. In recent years, large-group floor systems for breeding chickens have also been developed, equipped with automatic egg collection belts.

II. Classification by Growth Stage of Chickens (Using Laying Hens as an Example)
 

The same chicken may be housed in different systems at different stages.

1.Brooding Period (0-6 weeks):

• Environment: Raised in a strictly controlled brooding house for temperature and humidity.
• Method: Typically, brooding pens are used to section off an area within the house, providing heat lamps and specialized feeding and drinking equipment for chicks. Density is higher to facilitate warmth and精细 management.

2.Growing Period (7-17 weeks):

• Environment: Moved to a growing house.
• Method: May be floor-reared or kept in specialized growing cages. Space is larger than during the brooding period to allow for skeletal and organ development.

3. Period (18 weeks until culling):

• Environment: Transferred to the final laying house.
• Method: Housed in different systems based on the chosen method (enriched cages, floor farming, free-range, etc.).

As is well known, ventilation is the core of modern farming environmental control. Its fundamental goal is to create uniform, stable, and suitable temperature, humidity, and air quality (ammonia, carbon dioxide levels) for the flock inside the house under any season and external conditions.

Having previously understood the farming methods for different types of chickens, we will now discuss fan installation positions under different farming systems:

I. Enclosed Chicken Houses (Environmentally Controlled Houses) – Most common in intensive farming.
 

These houses have no windows and rely entirely on mechanical ventilation and artificial lighting. Fan installation positions are highly standardized.

1.Cross Ventilation (Most common in narrower houses)

• Fan Installation Position: A row of large exhaust fans (typically 36 inches/91 cm or larger in diameter) is evenly installed on one side wall (negative pressure end) of the house.
• Air Inlets: Adjustable air inlets are located on the opposite side wall.
• Airflow Path: Fans draw air out, creating negative pressure inside. Fresh outside air enters uniformly from the opposite wall, crosses the entire house horizontally, removing heat, moisture, and harmful gases.
• Applicability: Houses typically no wider than 12 meters. Common in caged layer houses and floor-reared broiler houses.

2.Tunnel Ventilation (Summer cooling mode, for wider houses)

• Fan Installation Position: All fans are concentrated on one end wall (gable, negative pressure end).
• Air Inlets: The entire opposite end wall serves as the air inlet (often equipped with a cooling pad system).
• Airflow Path: Fans operate at full capacity, causing air to flow longitudinally at high speed from one end to the other along the entire length of the house. The main purpose is to create a wind chill effect, lowering the birds' perceived temperature.
• Applicability: Large floor-reared broiler houses and grower houses. This is the most critical cooling ventilation method in summer.

3.Transitional/Mixed Ventilation (Spring and Autumn mode)

• Fan Installation Position: Some medium-sized fans are installed in the middle of the side walls or distributed along them.
• Purpose: During seasons not requiring maximum wind chill, these fans operate at lower power to provide gentle air exchange, prevent drafts, and save energy.
• Applicability: All types of enclosed houses during non-extreme temperature seasons.

4.Enhanced Tunnel Ventilation (An upgraded version of tunnel ventilation)

• Similar to tunnel ventilation, but the house is longer, the design more precise, airflow velocity higher, and cooling effect better. Fans are also concentrated on one end wall.

II. Open-Sided or Semi-Open Houses (Common in free-range, welfare farming, or hot regions)
 

These houses have windows or curtain side walls, relying more on natural ventilation.

Fan Installation Position:

• Supplementary Installation: Fans are not the sole means of ventilation.
• Flexible Positioning: Fans may be installed high on the side walls or at the ridge as exhaust fans.
• Main Purpose: To supplement and enhance airflow when natural wind is insufficient (e.g., on sultry, windless nights), expelling hot, moist air accumulating at the top.
• Fan Type: Circulation fans/stir fans are often used, installed on the ceiling inside the house to promote air mixing and prevent stratification.

III. Multi-Tier Cage Layer Houses (Mainstream in modern egg farms)

This is one of the most complex environmental control systems because the cages themselves severely obstruct airflow.

• Core Challenge for Fan Installation: How to make air effectively penetrate multiple cage tiers, reaching every layer and every bird.
• Installation Positions and Strategies:

1. Main Exhaust Fans: Still installed on side walls or gables to create negative pressure.
2. Key is "Air Distribution": The arrangement of cages and specially designed baffles/air ducts are crucial. After fresh air enters from inlets, it is directed via ducts into the aisles between every two rows of cages, then penetrates the cages horizontally or vertically.
3. In-House Circulation Fans: Almost essential. Installed above the aisles, they agitate the air in the central part of the house, breaking temperature and humidity differences between and within cage rows and tiers to ensure uniformity.
4. Pit Ventilation: Multi-tier cages have manure pits underneath with high ammonia concentration. Independent small exhaust fans for the manure pit are needed to continuously vent pit gases directly outside, preventing them from rising and affecting the flock.

IV. Influence of Different Growth Stages

Even within the same house, the age of the chickens changes the fan operation strategy.

• Brooding Period: Chicks require high temperatures and generate little heat themselves. Fan operation is minimal, focusing on minimum ventilation to ensure air quality without removing too much heat. Fans may run intermittently for short periods.
• Growing/Laying Period: The flock generates massive heat. Fans need to run continuously, transitioning from minimum ventilation mode to transitional ventilation, and finally to maximum ventilation (tunnel ventilation).

Summary: The farming method determines the house structure, the house structure determines the ventilation mode, and the ventilation mode ultimately determines the fan's installation position, type, and specifications.

For more information about poultry house fans, please contact: alisa.xie@maintexpt.com