The preferred environmental temperature of newborn rabbits.

The preferred environmental temperature (TE) and rates of oxygen consumption (VO2) around the thermal neutral range were measured in rabbits on the day of birth and 2, 7 and 14 days after birth. On day 0, the preferred TE was 38.0 +/- 0.8 degrees C, and it fell to 30.4 +/- 0.5 degrees C by day 14. Day-0 rabbits kept for 1 h in a warm (41 degrees C), neutral 39 degrees C) or cool (28 degrees C) environment selected a different TE at 39.8, 39.5 and 37.3 degrees C, giving colonic temperatures (TC) of 40.8, 39.9 and 37.7 degrees C, respectively. A similar phenomenon occurred on day 2, but not on day 7. It was concluded that newborn rabbits select a TE to match that which they experienced in utero and that this preferred TE changes after birth depending on the temperature of their surroundings and the development of their thermoregulatory control.