Hatchery ventilation best practices

The developing embryos inside incubating eggs require a balance of correct temperature, humidity and carbon dioxide to oxygen ratio. Striking this balance is only possible if hatchery rooms are properly ventilated. While most producers understand the essentials of hatchery ventilation, industry experts say they’re still seeing ventilation problems on-farm. 

Optimal embryo development takes place in a consistent environment. Incubators should only have to fine tune the air entering the room. In Canada, where seasonal temperatures vary widely, this can be especially challenging. 

In an online guide on hatchery ventilation essentials, Aviagen points out that incubator manufacturers make certain assumptions about the temperature and relative humidity of air entering the machine. These assumptions allow them to determine what the heating and cooling capacity of a machine should be in order to best control the internal environment. 

Manufacturers usually include recommendations for variables such as: Incubator air requirements per 1,000 eggs; minimum room air changes per 1,000 eggs; room air pressure; and exhaust plenum air pressure. According to the Aviagen guide, the important aspects of ventilation, therefore, are air volume supply, room pressure, air temperature and relative humidity.

Tolga Erkus, incubation specialist at Aviagen, says ventilation mistakes can be costly, as they cause hatchability, chick quality, predictability and biosecurity problems. While it’s difficult to put a number on what these problems cost producers, Erkus did say even a one per cent loss could be costly. 

All this being said, experts have weighed in on the most common hatchery ventilation mistakes producers make and how to avoid them.

1. Uneven air distribution
When it comes to proper ventilation, Erkus says it’s important to create an accurate and protected reference point for pressure sensors. Common errors he’s seen include uneven air distribution, including drafts and improper airspeed in chick holding rooms. 

Some hatcheries, he says, are using neutral pressures instead of slightly negative pressure at exhausts. Some are using high-range pressure sensors for low-pressure set points. 

To avoid ventilation issues, Erkus recommends buying air-handling units with 20 per cent higher capacity. “This will extend the life of the systems and give a chance to compensate for problems in challenging situations,” he says.

Erkus also recommends using efficient pressure control systems in setter and hatcher rooms. Well-insulated doors should be kept closed. 

“Avoid using high-range pressure sensors for regulating very low pressures,” he adds. “Don’t forget that pressure sensors have one per cent error; using a sensor error rate higher than the set-pint will cause serious fluctuations.”

Finally, he recommends cleaning air ducts and exhausts and calibrating pressure sensors and dampers periodically. 

2. Improper air handling units
Cobb-Vantress hatchery specialists Tommy Lively and Scott Jordan point out similar mistakes in the hatchery. They’ve seen undersized air handling units or units not designed for hatchery ventilation in use. 

“When the air handling unit is undersized, it is not able to provide enough air supply for the incubators or hatchers in the room, resulting in negative pressure in the fresh air plenum,” Lively says. “Negative pressure can cause overheated embryos and a spread in the hatch window due to microclimates inside the machines, which will increase seven-day mortality.”

3. Incorrect use of exhaust fans
Most hatcheries have a very large exhaust fan in the chick takeoff room to extract loose fluff during the pull process, Jordan says. This room should be negative to the clean tray room as well as the corridor hallways. 

However, some hatcheries have a very large exhaust fan with little or no inlet. The exhausted air must come from some other place in the hatchery, often the nearby hatcher or incubator rooms, he says. 

The exhaust fan ends up stealing air from the incubator or hatcher room and causing negative pressure there, Jordan says. “When air is also being stolen by an extraction fan, the air handling unit is unable to keep up with the ventilation needs, resulting in negative room pressure,” he says. 

4. Incorrect airflow
Another mistake Lively and Jordan often see is air flowing from dirty to clean areas. Air should always flow from the clean area towards the dirtier areas, they say. 

Since chick down is a source of bacterial contamination, it can cause infection and lead to an increase in seven-day mortality, Lively says. Use a manometer or anemometer to ensure airflow between the clean tray room and the chick takeoff room is flowing in the correct direction. 

Air should enter the clean tray room and move toward the chick takeoff room, Lively says. The optimum place to take this reading is close to the tray washing machine, he adds.

5. Poor door management
Rui Silva, a ventilation specialist at Jamesway Chick Master Incubator Inc., has seen several ventilation issues that impact quality and biosecurity, including poor door management. 

When rooms are improperly sealed or where door management is poor, air volume coming from the HVAC system will have to increase in order to compensate, Silva says. 

As a result, energy use and associated costs will rise, and the facility’s overall ecological footprint will increase. Poor ventilation can also lead to biosecurity issues, as air travels from dirty to clean areas in the hatchery, Silva says. 

6. Rooftop units mismanaged
Another issue Silva often sees involves rooftop discharge. Air temperature discharge, especially in rooftop units, is much higher than the set point on heating mode and much lower than the room set point on cooling mode, Silva says. The air also enters the room at a higher speed. Therefore, if the air of discharge grills is directed to the machines close to the grilles it can cause imbalance inside the machine, he says. 

7. Poor humidity control
Poor humidity control is also an issue in some hatcheries, Silva says. When humidity is too low dampers remain at minimum (low O₂/high CO₂). As a result, the machine compensates with spray, which leads to cold spots, wet eggs and a cold floor. The machine then calls for heating, creating imbalance between heating and cooling.

When humidity is too high dampers open to compensate, leading to excessive CO₂, poor humidity loss, poor embryo development and low chick quality, especially in old flocks, Silva says.

When temperatures outside are low, heating mode activates on the HVAC system, and the rising temperature lowers relative humidity. “In this case, humidity correction in the room is needed, with the addition of humidity – water spray – to the room via a dedicated humidification system,” Silva says. 

“To have a consistent RH value is key to a stable incubation operation, avoiding or reducing the need for the incubator machine to spray inside and lead to an unbalanced and inefficient operation.”

Basically, the more stable the air is with regards to temperature, relative humidity and pressure, the more efficient incubators will operate. Efficient incubators shorten the hatch window, and improve day-old chick uniformity and hatchability rates.

Improved efficiency will be reflected in all key performance indicators, including feed conversion ratios and a reduction in overall cost per kilogram, Silva concludes.