Thermal Control
Pigs lose heat by four natural methods
1 Conduction to the
floor
2 Convection to the air
3 Radiation to other
surfaces
4 Latent head (or
moisture) mainly by respiration
This is illustrated in the drawing
This is useful as it allows us to calculate what
extremes we can achieve by the four methods of heat loss.
For example (From Y. Choiniere and J. Munroe (1994):
A 7 kg weaner on a wire mesh floor produces around 29.5 watts of energy which it
needs to lose. The animal kept within
its thermal neutral zone without chilling in a standard nursery at 30•C.
Estimates can
be made for its heat losses:
If we placed the weaner on a heated surface, so that
the conduction to the floor was 0%, the pig
still has to lose 29.5 watts. The Latent
heat does not change, so we must allow the pig to loose more through radiation
and convection to maintain it within the thermal neutral zone. Now the estimates for heat loss are:
The room can now run at 23•C and the air flow can be
increased
This can provide a better
environment