Supplemental oxygen affects plasma insulin-like growth factors in embryos from selected lines of turkeys

Recent advances in our understanding of insulin-like growth factors (IGF) h ave improved our knowledge of the physiological roles of these peptide horm ones during avian embryogenesis. However, little is known about changes in plasma IGF in response to changes in environmental factors. The objective o f the studies reported herein was to examine the response of IGF-I and IGF- II in turkey embryos to changes in incubator gaseous conditions. Two experi ments were conducted in which the fractional percentage of oxygen in the in cubation atmosphere, a factor known to influence the energy metabolism of e mbryos, was investigated for Its effects on circulating IGF-I and IGF-II in developing: turkey embryos. Oxygenation during pipping and hatching is known to depress lactate, urates , and beta-hydroxybutyrate in growth-selected poult embryos, but elevate th em in randombred control poult embryos. Plasma concentrations of IGF-II wer e similarly depressed in the growth-selected hatchlings. Circulating growth factor concentrations were influenced by oxygenation in lines of turkeys i n which greater oxygen concentrations enhances cardiac growth. Enhanced car diac growth was inversely related to IGF-I concentrations in those genetic Lines of turkeys. It was concluded that changes in poult embryo energy balance as well as cha nges in growth to adapt to environmental incubator conditions may involve c hanges in IGF-I and IGF-II. These changes appeared dependent on the genetic s of embryos; embryos selected for growth show more fluctuation in response to environmental oxygen than embryos selected for egg production.