The effects of climatic conditions on production and health of farm animals. Thermoregulation of farm animals

Question 1

Sources of Heat:

Answer 1

• Exogen:
◦ Ambient Temperature
◦ Radiation (solar, thermal)
• Influential effect on heat sense: 
◦ Watervapor
◦ AirMovement
• Endogen
◦ Metabolism (better genotype-higher production-higher metabolism)

Question 2

Thermodynamic mechanisms

Answer 2

From Animal point of view:
• Counter current heat exchange to conserve and to lose heat
• Convection: body warms air or water
• Conduction: body is in contact with a cooler surface
• Radiation: IR radiation emmitted by the body is absorbed by cooler objects
• Evaporation: Water in definied bodyfluids (sweat, saliva) is converted into water vapor

Question 3

Water vapor in the air

Answer 3

• The water vapor content of the air play very important role, as it determines the rate of evaporative loss of body through skin and respiratory system.
• Wet Bulb Temperature (Twb), Relative Humidity (RH) or Dew Point Temperature (Tdp)
- describe the water vapor content of the air

Question 4

Psychrometry

Answer 4

Measurement of physical and thermodynamic properties of gas-wapor mixtures

Question 5

Air Velocity

Answer 5

• The wind has influence on convective heat exchange between animals and their environment.
• Measurement by anemometers (directional or non-directional, hot-wire, sonic or propeller)

Question 6

Solar and Thermal Radiation

Answer 6

1, shortwaves: direct sunlight
2, longwave: terrestrial surface originated radiation, the level of reflection and absorption is mainly depends on the surface characteristics
–> white colored animals have low absorptivity - higher reflectivity for short wave

• measured by pyranometers and by Vernone Globe Thermometers

Question 7

Optimal micro-climatic conditions - Ruminants

Answer 7

• cold conditions are better tolerated
• the major control mechanism in cold: evaporative heat loss control
• very wide TNZ
• too windy calf area is not acceptable
• cold floor may be unhealthy for young calves and may decrease milk production of cows
• pros: around weaning calf jacket is wildly recommended in cold weather to redice vulnerability, more energy for growth
• small ruminants with thick wool is resistant against cold
• newborn lambs and freshly sheared ewes may be vulnerable
• hot is much less tolerated
• heat stress: serious health issues, remarkable loss in productivity

Question 8

Optimal micro-climatic conditions - Swine -

Answer 8

• only 35-40% is utilized of the total genetic potential of modern swine breeds
• one of the major reasons: suboptimal microclimate conditions
• critical temp values are determined by live weight, BC, size of groups
• neonatal mortality
• cold tolerance of newborns are limited–> shivering is the only way of heat prod, muscular maturation is key element of thermoregulation
• continous monitoring systems are needed: infrared thermography (potential solution)

Question 9

Optimal micro-climatic conditions - Poultry -

Answer 9

• day old chicks: high temp demand (28-32oC)
• ensuring suffiecient ambient temp available by room heating system or combo of room heating and local heating system
• highest feed consumption 3-4th week, lower temp is better (15-20oC)
• broilers: generally heat tolerance is good
• egg yield is influenced significantly by heat stress (egg weight drops)
• optimal temp: 25oC
• hot and humid conditions are more challenging
• Automatic climate controllers, insulated buildings, well ventillated rooms, Negative pressure vent. systems are available.
  • Overcrowding must be avoided.