Efficiency of thermoregulatory control elements in precocial poultry embryos

摘要

To explain all aspects of the efficiency of the thermoregulatory system in poultry embryos, the activity and the dynamics of different control elements have to be investigated systematically during the prenatal period. The relevant methodology and results, cited in this paper are mainly from our own group but are compared with related experiments described in the scientific literature. They may be summarised: Thermoregulatory behaviour is developed early in poultry embryos. Temperature of allantoic fluid (T-af) represents the internal body temperature in the last third of incubation because T-af and T-c are much the same at normal (37.5degreesC) and low incubation temperatures (34.5degreesC) after internal pipping. Fowl embryos show endothermic reactions from day 14 and Muscovy duck embryos from day 22. In precocial avian embryos, body core temperature increases in accordance with heat production. In contrast to heat production the efficiency of heat loss is high in precocial avian embryos. Development of physiological control systems starts with non-co-ordinated and proximate (immediate) non-adaptive reactions.