The sow surface temperatures and respiration rate
increased with increasing room temperatures, indicating
thermoregulation in terms of heat loss by increased blood
fl ow to the skin and evaporation from the lungs. Black et al.
(1993) proposed the hypothesis that increase in blood fl ow
to the skin to assist heat loss takes place at the expense
of the mammary gland. Even though thermoregulation is
energy demanding, we have in our data no evidence of
negative consequences in terms of increased lactational
BW loss in the sows or reduced litter growth in the
temperature range of 15°C to 25°C. The data confi rm
the suggestion by Quiniou and Noblet (1999) that the
evaporative critical temperature is below 22°C;