Principles of Thermoneutrality in Poultry Production Flashcards
Thermoregulation in Birds
Birds are generally _ organisms
Body Temperature: - degrees C
Internal body temp is regulated by _
- functions as a thermostat
Homeothermic
41-42 degrees C
Hypothalamus
Birds eat _ times their something
Compare to _ cans of coke and _ of cars
5x
210 cans of coke; gas of cars
Heat Production of Birds
Broilers produces
- _ Btu/kg sensible heat
- _ Btu/kg respiratory heat
Heat prod of 2.3k birds
- _ Btu/hr
- equivalent to _ brooders
Broilers produces
- 11 Btu/kg sensible heat
- 15.4 Btu/kg respiratory heat
Heat prod of 2.3k birds
- 625,000 Btu/hr
- equivalent to 30 brooders
Energy Metabolism
Majority of Metabolisable Energy is lost in?
Gross Energy -> Faecal energy and Digestible energy (DE)
Digestible energy (DE) -> Metabolisable energy (ME), urine, methane (gas)
Metabolisable energy -> HEAT and Net energy
Net energy -> Maintenance energy and Production energy
Maintenance energy <-> Heat
- Loss of heat by evaporation of water (via respiration)
- Emission of electromagnetic heat
- Direct transfer by contact
- Moving air removes radiated heat
- Evaporation
- Radiation
- Conduction
- Convection
Thermoregulation of the hen
Excess body heat is removed by 4 different mechanisms
1. Body heat lost to cooler surrounding air; aided with air movement by creating wind chill effect
- _ - blood swollen wattles and comb bring internal body heat to surface to be lost to cooler surrounding air
2. Electromagnetic waves transfer heat through the air to a distant object; to cooler objects
3. Rapid, shallow, open mouth breathing increases heat loss by increasing evap of water from mouth and respiratory tract; aided by lower air humidity
4. Body heat loss to cooler object in direct contact with bird; will seek cooler places
- Convection
- Vasodilation - Radiation
- Evaporative Cooling
- Conduction
Effects of Heat Stress
Low feed intake, egg prod, egg weight, shell quality, albumen height, growth, hatchability
High mortality, cannibalism, immunosuppression, fertility in roosters
Production losses occurring from the heat stress depend on:
- Max temp to which flock was exposed
- Duration of high temperatures
- Rate of temp change
- Relative humidity of air
Comfortable Climate
Temperature/Humidity Index Formula
X Temperature
Y Humidity
Temperature + Relative Humidity = 90 + Age in Weeks
~ humidity is important factor
Thermoneutral Zone
Heat Production = Heat Loss
Zone of survival, homeothermy, thermoneutrality, thermal comfort
Lower and upper critical temp
Death from cold and heat
Core body temp and heat prod
Heat Loss Percentage
45% through skin
55% through breathing
- reduce difference between floor and air temperature to a minimum so not too hot or cold for walking/sitting chicks
Heat Formula
Heat = Temperature + Moisture
Hot air can hold much moisture
Air cools and shrinks and can no longer retain or absorb moisture so evap stops and condensation may occur
Temperature and Relative Humidity Graph
Temp is low in the morning and evening, high at noon
Relative humidity is high in the morning and evening, low at noon
Mollier Diagram
4.5% Rel Humidity increase for ever 1 degrees C cooling
Reduction in temp by 6 degrees C will increase % RH by about 27%
Mortalities due to heat stress occur when the temp drops normally in
late afternoon
Heat Stress in Poultry
Determined by the combination of temperature, humidity, and air movement
At some combination of these factors above comfort, the bird is in a stressful situation and responds by reducing feed intake
Birds comfort
When the particular combination of temp, humidity, and air movement result in reduction in normal level of feed intake
Heat stress
Water consumption
Depends on feed intake, food composition, house temp, and age
Water intake
Normally: 1.6-2x amount of feed
High temp: 3-4x amount of feed
High salt content: 4x amount of feed or more
~ manage heat, temp, humidity (manure)
~ not just temp, but humidity rin
Wet litter causes
Poor diet, ventilation, water pipe management
Kidney and digestive disorders
Excessive broiler density
High relative humidity
