Central and peripheral temperatures and EEG changes during behavioural thermoregulation in pigs

Area of Science:

• Animal Behavior and Physiology
• Thermoregulation
• Neuroscience

Background:

• Understanding how young pigs thermoregulate is crucial for animal welfare and agricultural practices.
• Pigs' ability to learn and adapt to thermal environments influences their behavior and physiological responses.
• Previous research has explored thermal comfort zones, but detailed neurophysiological responses are less understood.

Purpose of the Study:

• To investigate the learning capabilities of pigs in operating infra-red heaters at different ambient temperatures.
• To examine the physiological responses (hypothalamic, cortical EEG, skin temperatures) of pigs to varying ambient temperatures in heat-seeking and heat-avoidance scenarios.
• To determine the effect of preoptic region temperature manipulation on heating behavior and skin temperature.

Main Methods:

• Pigs (approx. 8 weeks old) were tested for their ability to operate infra-red heaters at 20°C and 25°C.
• Physiological data, including hypothalamic temperature, cortical electroencephalogram (EEG), and skin temperatures, were recorded in pigs exposed to 0°C, +10°C, and +20°C ambient temperatures.
• Behavioral responses were assessed in both heat reinforcement and heat escape situations, with targeted cooling of the preoptic region using a thermode.

Main Results:

• Pigs learned to operate heaters at 20°C but not at 25°C.
• Heating duration decreased with increasing ambient temperature, with no significant difference between heat reinforcement and escape situations.
• At 0°C, pigs maintained higher skin temperatures near heaters compared to +10°C; cooling the preoptic region increased heating duration and skin temperature (45-47°C).

Conclusions:

• Young pigs demonstrate a learning threshold for thermal regulation, preferring cooler environments for heat-seeking behavior.
• Physiological responses indicate active thermoregulation, with preoptic region cooling significantly influencing heating behavior and skin temperature.
• The findings provide valuable insights into the neuro-behavioral mechanisms of thermoregulation in developing pigs.