The Effect of Age and Holding Temperatures on Hatchability of Turkey and Chicken Eggs

THE embryo of the hen at the time the egg is discharged from the oviduct has, according to Patton (1929) and others, reached approximately the gastrula stage. This period of development is marked by the formation of the gastrocoele (primitive gut) in which the cells of the blastoderm have invaginated into the segmentation cavity. Future development from this point is dependent on temperature. A cessation in development occurs when the embryo is held below physiological zero, 20°C. to 21°C. (68°F. to 69.8°F.). The question of how long fertile eggs may be held before setting and yet be capable of developing into normal chicks has been investigated by a number of workers. Broca (1862) as quoted by Lippincott (1927) observed that blastoderms 27 days of age at time of setting frequently developed for a short period and then died. Lippincott (loc. cit.) quotes Lavison (1862) as having obtained a few normal . . .