Broiler Ventilation Requirements In Response To Higher Welfare Standards

Bernard Green

Topics• Thermoneutral zone• What is ventilation?• 3 Ventilation systems• Difficult climates• Wet litter• Control systems

Welfare Requirements• Welfare requirements from a ventilation perspective• These may differ from country to country• Should ALL have one thing in common……• KEEP THE BIRDS COMFORTABLE• “Thermoneutral Zone”

Thermoneutral Zone• Temperature zone in which the birds are able to keep

their body temperature constant with the help of physical heat regulation

• Lowest Critical Temperature (LCT) - lowest temperature in the thermoneutral zone

• Below LCT – bird uses feed energy to warm itself• Highest Critical Temperature (HCT) - highest

temperature in the thermoneutral zone.• Above HCT - birds can no longer dissipate their heat.• They will start to consume less feed and production

will drop as a result.

A – Visual behaviour : ruffle feathers, huddle

B – Visual behaviour : hold wings away from body, pant

A

Cool

B

Warm

ColdStress

Heat Stress

Ventilation Systems• Outside of TNZ, bird behaviour changes• We can see, interpret these changes (hopefully)• We should ventilate based on these observations• Every ventilation decision should be based on:

• Bird activity, comfort, and/or• Air quality

Importance of TNZWelfare view point:• Comfortable birds• Healthy birds

Business view point:• Healthy birds• Better liveability• Better FCR• Better growth• Better performance

Thermoneutral Zone• TNZ does not remain constant• It changes during the birds life• Breed company guideline• Set point temperature vs bird age• ± 32 – 21ºC• Is thermometer temperature all we need to monitor?

Temperature and Humidity

Windchill Example (UGA)

0.5 1.0 1.5 2.0 2.5 3.0

Air Velocity (m/s)

8.0

5.5

3.5

1.0

9.0

6.5

4.5

2.0Win

d Ch

ill (°

C)

Example: Air temperature 30ºC; Air speed 3m/s

Thermometer will show 30ºC; Birds will feel ±22°C

Outside Climate• Climate has a major impact on house conditions• Cold, hot and dry, hot and humid• Hot and humid – worst climate

• Cold – we can add heat• Hot and dry – evaporative cooling is effective• Hot and humid – partial cooling + lots of air speed

Difficulty in Maintaining TNZ3 Major contributing factors:1. Bird’s age – changes daily2. TNZ shifting every day3. Ambient conditions can change hourly

Keeping birds in their TNZ is not straight forward!

Ventilation System• If you want to keep your birds comfortable, you need a

good ventilation system• Regardless of your location around the world

“Ventilation system” includes:• House• Ventilation equipment• Control system• Management (stockman skills)

What Is Ventilation?Ventilation is all about control of:• Where the air enters the house• Where it doesn’t enter• How much enters• Where it goes in the house (up, down, onto the birds)• How fast it travels over the birds• The temperature of the air (limited control)

If you are hoping to keep birds in/near their TNZ, you must have “control of the air”

The Starting Point• A good ventilation system starts with a “good quality”

poultry house• Most ventilation systems operate on negative pressure• Houses must be well sealed, “air tight”• This provides control of where air will and won’t enter• Easier to generate negative pressure to move air• Insulation plays an important role• Keeps heat out in hot weather, and in during cold weather• A good house is:

• Well sealed, air tight• Well insulated

Ventilation SystemsMost houses should have 3 ventilation systems:1.Minimum Ventilation2.Transitional Ventilation3.Tunnel Ventilation

Minimum Ventilation• Operates at and below the set point temperature• Heating is used to keep the birds comfortable• Air is introduced through side wall inlets• Inlets distributed along house length• Inlets operate with negative pressure• Direct the cold air away from the birds along the ceiling• Fans operate ON/OFF (cycle timer)• Manage cycle timer based on air quality

Transitional Ventilation• Operates above the set point• Purpose is to remove heat from the house• Fans run continuously• Air enters through side wall inlets• Tunnel inlet is closed• Inlets are equally distributed along length of house• Air is still directed away from the birds along the ceiling

Tunnel Ventilation• Air enters at one end of the house• Air is pulled through the length of the house• Air flow is “on” the birds• Number of fans determine the air speed• Use wind chill factor• Try to control the birds effective temperature• Evaporative cooling can be used to lower air

temperature

3 Ventilation Systems

Set Point Temperature

Minimum Ventilation (cold outside)

Transitional Ventilation (too warm for minimum ventilation, not hot enough for tunnel ventilation)

Tunnel Ventilation (hot outside)

The above could vary based on your annual ambient climate

Cool Optimum Warm

Minimum – provide heat, ventilate for air qualityTransitional – ventilate to remove heat, minimal air on the birdsTunnel – move air over birds, wind chill, effective temperature

Difficult Climatic Conditions• Minimum ventilation – not usually a problem with a good

house, enough heating (management)• Transitional ventilation – not a problem (management)• Tunnel ventilation – hot and humid conditions are a

problem

Hot and Humid Conditions• When birds are hot, they pant• Panting uses “internal evaporative cooling” to release

heat• The more humid the air around the bird, the less effective

is the panting process• Cooling pads can be used to lower air temperature• The more humid the outside air, the less cooling• Evaporative cooling increases RH• In hot, humid conditions air speed and air exchange is

critical• House design must be right!

Wet Litter• Very often occurs during cold weather, winter• Is it because outside is cold with high RH?• No• The colder it is, the “easier” to control RH• Minimum ventilation is often more about controlling

moisture (RH), than supplying “fresh air”

Phone App (PsychroApp)Available on Play Store and App Store

Guideline : for every 10ºC you warm the air, RH will reduce by 50%

Why Do I Have Wet Litter?Question :• If RH decreases when I warm the air, then why do I get high

RH in my house and wet litter?Answer :• The air gets warm, RH decreases• The air absorbs moisture in the house from the birds, litter,

drinkers• RH increases• CYCLE TIMER FANS MUST REMOVE THE MOISTURE• If the fans do not operate enough, RH will increase and

eventually put more moisture back into litter• CYCLE TIMER SETTING IS CRITICAL

Control Systems (and Operators)• Control systems are responsible for how the ventilation

system operates• Thermometers/sensors measure temperature• Temperature activates and deactivates fans• The controller settings/program will determine the

conditions in the house

Control Systems (and Operators)Bird behaviour should dictate controller settings

NOTController settings determine bird behaviour

• Keep control systems “easy to use and understand”• Be sure to keep “teaching” the controller what you are

seeing in the house• The controller is there 24/7• If you don’t “teach” it what you see in the birds, don’t

expect it to look after them when you’re not there

www.aviagen.com