Length of the plateau and pipping stages of incubation affects the physiology and survival of turkeys

1. The hypothesis tested was that accelerating the vate at which a turkey e mbryo passes through the Plateau and Pipping stages (incubation days 25 to 28) affects growth and embryonic mortality. 2. Eggs from 4 genetic lines were incubated similarly until 24-d of incubat ion. The eggs were divided at random, half incubated at 36.8 degrees C (CON ) and the remaining half incubated at 37.3 degrees C (FAST). 3. The passage time for each developmental stage was recorded at 4 h interv als. Tissues were collected and measured for growth, and glycogen concentra tion at each developmental stage in response to the accelerated development . 4. The FAST treatment accelerated passage through the Plateau in some lines but not others, but time to pip was shortened in all genetic lines. Embryo nic survival rate was affected differently by FAST. Slower growth in respon se to FAST enhanced survival. 5. In conclusion the rate at which genetically different embryos grey matur e and survive may involve choices among the 3 processes.