Incubation temperature affects plasma insulin-like growth factors in embryos from selected lines of turkeys.
An experiment was conducted to test the hypothesis that incubator temperature may affect circulating insulin-like growth factors (IGF-I and IGF-II). In prior studies, growth of turkey embryos was altered by increasing incubator temperatures. Interestingly, the embryonic growth of a growth-selected line (F) was reduced, whereas embryos from an egg-production-selected line (E) did not alter embryonic growth but altered organogenesis. Growth of the F and E lines was altered experimentally in the current study by increasing incubator temperature from 36.8 to 37.2 C during the last 3 d of incubation. Embryonic blood samples were taken and analyzed for glucose, glucagon, IGF-I, and IGF-II concentrations. Increased incubator temperature elevated embryonic plasma glucose concentrations of all treatments compared to controls, which was accompanied by increased plasma glucagon concentration only in the E line embryos. Line and treatment interacted to affect IGF-I and IGF-II concentrations of embryo and hatchlings. Line E embryos increased IGF-I in response to the higher temperature, but controls did not; F embryos altered IGF-II in response to treatment, but controls did not. Alterations in IGF-I in E corresponded to growth responses, whereas IGF-II in F corresponded to metabolic responses. We concluded that changes in turkey embryo growth rates to incubator temperature involved changes in IGF-I. Additionally, IGF-II and glucagon are involved in intermediary metabolism during higher temperature exposure.
Christensen
V L
VL
Department of Poultry Science, North Carolina State University, Raleigh 27695-7608, USA. vern_christensen@ncsu.edu
McMurtry
J P
JP
Donaldson
W E
WE
Nestor
K E
KE
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004625:Embryo, Nonmammalian / Q000098:blood supply*; D047108:Embryonic Development; D005934:Glucagon / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007335:Insulin-Like Growth Factor II / Q000032:analysis*; D013696:Temperature; D014422:Turkeys / Q000196:embryology*
D001786:Blood Glucose; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D005934:Glucagon