Tazawa H, Rahn H
J Exp Zool Suppl. 1987;1:105-9.
Is a new quasiequilibrium state of metabolism and egg temperature reached after chick embryos and hatchlings are exposed to prolonged cooling? During the last half of the incubation period the chicken egg maintains a temperature above that of the ambient air temperature of 38 degrees C. This difference increases from about 0.2 degree C at 11 days to 2 degrees C just before hatching and to 3 degrees C by 7 days posthatching. When eggs or hatchlings are then exposed to room air at 28 degrees C, a new quasiequilibrium state is reached in 5 hr (defined as a change in egg temperature of less than 0.1 degree C X hr-1). The new difference between egg and ambient temperature varies from about 0.1 degree C at 11 days to 1.2 degrees C just before hatching, but increases in the hatchling from 6 degrees C right after hatching to 10 degrees C 5 days later. During the quasiequilibrium state at 24 degrees C the metabolic rate is maintained at about 40% of the control value up to hatching time, but thereafter rapidly increases to 70-95% by day 1. In a few cases emergence from the shell was not necessary for increases in quasiequilibrium temperature and metabolic rate.
雏鸡胚胎和幼雏在经历长时间冷却后，是否会达到新陈代谢和蛋温的新准平衡状态？在孵化期的后半段，鸡蛋维持的温度高于环境空气温度38摄氏度。这种温差从第11天的约0.2摄氏度增加到孵化前的2摄氏度，到孵化后7天增加到3摄氏度。当鸡蛋或幼雏随后暴露于28摄氏度的室内空气时，5小时内会达到新的准平衡状态（定义为蛋温变化小于0.1摄氏度/小时）。蛋温和环境温度之间的新温差在第11天约为0.1摄氏度，到孵化前为1.2摄氏度，但幼雏孵化后立即从6摄氏度增加到5天后的10摄氏度。在24摄氏度的准平衡状态下，直到孵化时新陈代谢率维持在对照值的约40%，但此后到第1天迅速增加到70 - 95%。在少数情况下，蛋壳破裂并非准平衡温度和新陈代谢率增加的必要条件。
