Modifications of operant thermoregulatory behavior of the young pig by environmental temperature and food availability.
Piglets (Sus scrofa domesticus) were weaned at 14 days and acclimated to 10 ("cold animals") or 35 degrees C ("warm animals"). Cold animals were either fed ad lib. (10HH) or maintained on a high (10H) or low (10L) nutrition plane. Warm animals were maintained on a high (35H), low (35L), or a very low (35LL) nutrition plane. After 3 weeks of acclimation, operant thermoregulatory behavior (animals pressed a lever to turn on a heater) at 15 degrees C was assessed immediately following or 22 h after a meal. It was found that cold piglets or those on low nutrition planes produced more heat reinforcements than warm piglets and those on high nutrition planes. All animals tested 22 h after a meal produced more reinforcements than when tested immediately after a meal. Rectal temperature before the sessions of operant heating was lower in cold animals and those on low nutrition planes than in warm animals and those on high nutrition planes, but the difference dissipated after 90 min of access to heat. Piglets were then "deacclimated" for 24 h at 25 degrees C and their behavior observed once again. Deacclimation eliminated the effect of acclimation temperature on body temperature and behavior but it did not eliminate the effect due to nutrition. There was no interaction between temperature of acclimation and nutrition. The experiments demonstrate that the body temperature of the pig is independently affected by environmental temperature, the quantity of food eaten by the animal, and a possibility to use behavior. The behavioral drive is to reach body temperature which can be defined as a thermal set-point (temperature at which there is no need for a thermoregulatory response to occur) for behavioral thermoregulatory responses. Adaptation to different environmental conditions does not affect this behavioral set-point, but it can involve a temporary shift in the set points for specific autonomic thermoregulatory responses.
Swiergiel
A H
AH
Department of Pharmacology and Therapeutics, Louisiana State University Medical Center, Shreveport 71130-3932, USA. aswier@lsumc.edu
D000064:Acclimatization / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology*; D004435:Eating / Q000502:physiology; D004777:Environment; D005502:Food; D006128:Growth / Q000502:physiology; D008297:Male; D013552:Swine; D013696:Temperature