Management tips
for ventilating broilers

Management tips for ventilating broilers in hot and humid conditions
Many areas in the central regions of the world are well known for hot and humid conditions. Temperatures and relative humidity (RH) averaging over 25°C and 80% RH are common for several periods of the year. These hot and humid conditions provide a challenge to achieve top broiler performance.

See the examples below showing a typical yearly average daily temperature/humidity high and low profile in tropical parts of the world.

Closed vs. open production environment
It is well recognized that a closed production environment with a good quality ventilation system and a combination of side and tunnel ventilation, will achieve significantly better broiler performance than a traditional open house system. Lower mortality, higher stocking density, improved FCR, and average daily gain is better when comparing the enclosed environment and open house systems. As a rule of thumb, if implemented properly, a house with a controlled environment can improve overall productivity by up to 20% compared to an open house.

Using chill effect
The use of tunnel ventilation in hot and humid conditions enables a large air volume to remove heat from the birds by producing a chill effect. The reduction in effective temperature felt by the birds using air movement is called the chill effect. The air movement removes heat generated by the birds' bodies as they increase in age. Increasing the volume of airflow creates a lower effective temperature for the bird, and it feels cooler. The key message of this article is "hot, and high humidity conditions are best managed by high airspeed."

A key point in assessing the chill effect is bird age. Younger, less feathered birds will feel a lower effective temperature at the same wind speed than older, better-feathered birds. Explained by older birds have less skin surface compared to younger birds. This fact will reduce the cooling effect of wind speed on older birds. Other factors, such as stocking density and relative humidity, should be considered when assessing the most effective temperature in the house. Observation of the birds in the house is the best method to determine ideal conditions for each age stage.

Evaporative cooling
You find evaporative cooling pads in the tunnel ventilation section of the house. The energy absorbed during evaporation reduces the air temperature in the house. Airflow creates a cooling effect that can reduce the house temperature by 10°C or more. Maximum evaporation is achieved when water pumps are set to provide just enough pad moisture to ensure optimum water evaporation. If too much water is added to the pads, it will most likely lead to higher relative humidity. In some cases, a higher effective temperature in the house.

Below, we have listed management tips to help you mount possible challenges in hot and humid conditions.

Contact your local SKOV Sales Manager to discuss how to improve your broiler productivity by optimizing ventilation in hot and humid conditions.

Ensure that the fan capacity produces enough chill effect in the house to cool birds later in the broiler grow out. The wind chill is significantly reduced when the outside temperatures exceed 32°C. Therefore, you have to use cooling to lower the house temperature below 32°C. A wind speed exceeding 3 m/sec is recommended in hot and humid conditions.

Check fans, cool cells, and the evaporative cooling system for any maintenance regularly. We recommend a special focus on equipment maintenance before the yearly peak in hot and humid conditions.

Birds cool down by using internal evaporative cooling through their respiratory tracks by panting to cool themselves. This form of thermoregulation is less effective as humidity increases in the house. Where the temperature increases and RH is high, you need to find the optimum balance between wind speed, temperature, and humidity. The chill effect is effective until the temperature reaches 32oC. The birds' internal evaporative cooling is effective until the RH reaches 80%. Therefore, be careful with the use of evaporative cooling pads, as they will increase the house humidity levels while in use. As a rule, for every 1°C reduction in house temperature by evaporative cooling methods, the relative humidity increases by 4-6%.

As a guide:

Temperature < 33oC - Use pad cooling with a limit of 80% RH in the house
Temperature 33-36oC - Use pad cooling with a limit of 85% RH in the house

Temperature > 36oC - Use pad cooling with a limit of 90% RN in the house

You can set a SKOV climate controller at a maximum RH setting to limit pad cooling and automatically reduce the chill factor when the temperature exceeds 32oC.

Night-time ventilation can be your friend. Older birds can benefit from running tunnel ventilation through the night. It will allow the birds the opportunity to cool down after hot daytime conditions. As a guide, to enable the bird to get rid of day-time heat's excess build-up, the night-time temperature can drop significantly compared to day-time temperatures. With older birds (>25 days / >1.8 kg) you can allow night-time temperature to drop 15-18oC below the day-time temperature.

Reduce or turn off evaporative cooling at night and run maximum tunnel fan operation to reduce daytime temperatures.

Evaporative cooling will lower the inside house temperature. However, as stated above, evaporative cooling can also stress the birds by raising humidity and limiting the birds' ability to cool themselves. Never let the evaporative cooling turn off a fan. Firstly, ask your service technician to adjust the cooling cycle timer, thereby only using the minimum water volume to produce cooling. Evaporative cooling should complement tunnel ventilation. It is not a replacement for house cooling with ventilation fans. The SKOV climate controller gives the user the option to prioritize maximum energy savings by starting cooling before maximum airspeed or prioritizing bird comfort by starting cooling after maximum airspeed is achieved.

Raise the evaporative cooling "on" by 1°C if evaporative cooling is coming "on," and its operation causes a fan or fans to turn off. Or adjust the evaporative cooling timer in the first instance.

Consider the house temperature setpoint when managing birds in hot and humid conditions. Set the house temperature to a setting where you see the birds are comfortable in the house. Target an internal house temperature setpoint of 28°C in hot and humid conditions. Use the fogging system in the house first, if available. Then use evaporative cooling to help reduce high house temperatures at the 28oC target.

When checking the house temperature, look at the sensors at the tunnel fan end (warmer end) of the house rather than an average of two or three sensors.

The European style of poultry houses tends to be very wide with relatively high ceilings. This type of housing using tunnel ventilation in hot conditions and humid conditions can lead to cooler temperatures at the front of the house and warmer temperatures at the back. Birds will naturally migrate towards the cooler part of the house, increasing stocking densities and potentially overcrowding of the feeders and drinkers.

Use fences installed in the house to prevent bird migration and improve bird uniformity.

Consider installing more fan capacity to even out the house's temperature variance if the temperature difference between front and rear exceeds 4°C.

Water usage, especially water wastage, can add unnecessary humidity in the house, causing respiratory stress to the birds.

Monitor the water supply in the house daily for correct drinker height, water pressure, water/feed ratio, and faulty equipment to avoid any unnecessary water wastage.

Consider the stocking density in the house during hot and humid periods of the year.

Consider lowering stocking density in the house during peak hot and humid periods to help maximize bird performance.