Meeting Abstract
10.5 Monday, Jan. 4 A reassessment of the proximate factors that trigger hypothermia in Japanese quail Coturnix japonica BEN-HAMO, Miriam*; PINSHOW, Berry; MCWILLIAMS, Scott R.; BAUCHINGER, Ulf; Ben-Gurion University of the Negev, Israel; Ben-Gurion University of the Negev, Israel; University of Rhode Island, Kingston.; University of Rhode Island, Kingston. miriammi@bgu.ac.il
We tested three hypotheses about the environmental cues that elicit facultative hypothermia in birds and the energy savings associated with reduced body temperature (Tb) using Japanese quail (Coturnix japonica) as a model: 1) Ambient temperature (Ta) influences the onset and depth of hypothermia (sleep Tb < euthermic sleep Tb) in Japanese quail; 2) Ta does not affect their use of hypothermia; 3) Ta acts along with body energy reserves in shaping the birds’ use of hypothermia. Eight quail were maintained within their thermoneutral zone (TNZ) at 32.6 ± 0.2 °C, and eight below their lower critical temperature (Tlc) at 12.7 ± 3.0 °C for 10 days. All the quail entered hypothermia upon 4 days of food deprivation, even quail kept within their TNZ, wherein thermoregulatory costs are ostensibly minimal in active animals. Tb decreased more (38.36 ± 0.53 °C vs. 39.57 ± 0.57 °C) and body mass (mb) loss was greater (21.0 ± 7.20 g vs.12.8 ± 2.62 g) in those quail kept at the lower Ta, and the energy saved by using hypothermia was greater (45.01 ± 4.54 % vs. 28.06 ± 3.33 %) for quail kept at low Ta than those kept within their TNZ. Interestingly, depth of hypothermia was positively correlated with mb loss in low Ta quail, but not in TNZ birds. We conclude that the data supports hypothesis (3) that both thermoregulatory costs and body energy reserves are proximate cues for entry into hypothermia in quail. This is not surprising below the Tlc, however, the quail responded to food deprivation by entering hypothermia within their TNZ with no apparent dependence on mb loss. Apparently, cues other than thermoregulatory costs and body condition are involved with the use of hypothermia within the TNZ.
