The effects of incubation conditions on the embryonic respiratory and mitochondrial energy metabolism, the thyroid hormone status, and the daily gainin turkeys

The embryonic oxygen consumption of turkeys during the time of incubation i s comparable with other bird species. The incubation of turkey eggs at diff erent temperatures (36.8, 37.8 and 38.8 degreesC) influenced the pre- and p osthatching developmental processes. Oxygen consumption increased with incu bation temperature. The embryonal losses were highest at 36.8 and 38.8 degr eesC. The critical time of incubation was between day 19 and 23. The birds incubated at 36.8 and 38.8 degreesC showed the lowest daily gain. These dat a were correlated with endocrinological criteria (thyroid hormone), the mit ochondrial and the enzymes activities (GLDH and SDH). Females showed higher mitochondrial activities. The higher correlation between oxygen consumption and daily gain found unde r suboptimal incubation conditions (36.8 and 38.8 degreesC) could be used f or practical selection. Furthermore oxygen consumption on day 19 was correl ated with hatchability.