Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 1999
Publication Date: July 1, 1999
Interpretive Summary: Prior studies with genetic lines of turkeys selected for rapid growth or increased egg production showed that environmental oxygen has a vital role in embryo survival. It has been previously shown that the insulin-like growth factors can influence many metabolites important to metabolism. Therefore this study was conducted to determine the effect of altered incubator oxygen levels on circulating growth factor levels. The results of this study showed that changes in environmental incubator oxygen levels can induce changes in blood growth factor levels. These changes were dependent on the genetics of the embryos with greater fluctuations in growth selected embryos versus embryos selected for egg production. These results suggest that changes in embryo survival and hatching rates can be altered by changes in plasma growth factor levels during incubation. This information will be of interest to other scientists.
Recent advances in our understanding of insulin-like growth factors (IGF) have improved our knowledge of the physiological roles of these peptides during avian embryogenesis. However, little is known about changes in plasma IGFs in response to changes in environmental factors. The objective of this study was to examine the response of IGF1 and IGF2 in turkey embryos to changes in incubator gaseous conditions. Two experiments were conducted in which the fractional percentage of oxygen in the incubation atmosphere, a factor known to influence the energy metabolism of embryos, was investigated as affecting circulating IGF1 or IGF2 in developing turkey embryos. Oxygenation during pipping and hatching is known to depress lactate, urates, and b-hydroxybutyrate in growth-selected poult embryos, while elevating it in randonbred control embryos. Plasma concentrations of IGF2 were similarly depressed in growth-selected hatchlings. Circulating growth factor concentrations were influenced by oxygenation in lines of turkeys in which greater oxygen concentrations enhanced cardiac growth. It was concluded that changes in poult embryo energy balance as well as changes in growth to adapt to environmental incubator conditions may involve changes in IGF1 and IGF2. These changes appeared dependent upon the genetics of embryos with embryos selected for growth showing more fluctuation in response to the environmental oxygen than did embryos selected for egg production.