Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2001
Publication Date: N/A
Interpretive Summary: For several years increases in mortality rates of turkey embryos during incubation has become a significant problem for the turkey industry. At present there is no clear evidence as to why this is occurring. Many factors can influence the potential hatchability of turkey embryos. A family of hormones termed the insulin-like growth factors, IGF1 and IGF2, are known to be vital to embryonic development. This study was conducted to determine whether changes in incubator temperature would influence plasma levels of these growth factors in embryos from a growth selected line of turkey embryos compared to embryos selected for egg production. The results demonstrated that increasing incubator temperature will significantly increase circulating IGF1 in growth selected embryos but not the other embryos. It is concluded that incubator temperature can differentially influence the levels of hormones important to normal embryonic development. This information would be of interest to turkey producers as well as other scientists.
Recent advances in our understanding of insulin-like growth factors (IGF1 and IGF2) have improved our knowledge of the physiological roles of these factors. Prior studies indicated that supplementing oxygen to incubation cabinets of incubating turkey embryos can change the concentrations of these growth factors. An experiment was conducted in turkey embryos in which the environmental temperature during hatching was investigated to determine its effect on circulating IGF1 and IGF2. When development of turkey embryos was accelerated by increased temperature during times of limited access to oxygen, growth selected lines reduced growth rates to survive whereas embryos from lines selected for egg production did not. Growth changes were also accompanied by changes in plasma concentrations of IGF1, whereas IGF2 was associated with fewer growth changes. The increased temperature increased IGF1 concentrations prior to pipping, and resulted in interactions of line and temperature in the hatchling IGF1 concentrations. Hatchling IGF1 concentrations differed in nonselected lines but those of selected lines were unchanged. It was concluded that changes in poult embryo growth rates to adapt to environmental incubator temperature as well as changes in embryo energy balance may involve changes in IGF1. These changes appeared dependent upon the genetics of embryos with embryos from lines selected for fast growth exhibited more fluctuation in IGF1 than IGF2 in response to the environment than did embryos from a line selected for increased egg production.