Effect of supplemental oxygen on blood plasma organic acids within embryosfrom selected lines of turkeys

The hypothesis was tested that increased oxygen tensions during the plateau stage of oxygen consumption (25 and 26 d of incubation) would cause differ ent metabolic responses from embryos selected for increased egg production or growth. Embryos were exposed to 171 or 152 mm Hg partial pressure of oxy gen from 25 to 28 d of incubation, a time when the oxygen conductance prope rties of the eggshell ape exceeded by the embryonic tissue demands for oxyg en. Carbohydrate and lipid metabolism were observed by measuring plasma org anic acids in embryos from selected lines and randombred controls. (E was s elected for increased egg production; RBC1 is the randombred line from whic h it was selected. F was selected for increased BW; RBC2 is the randombred line from which it was selected.) During the plateau stage in oxygen consum ption, RBC2 embryos responded to added oxygen by utilizing fat rather than carbohydrate, whereas F embryos responded by using less fat as well as less carbohydrate from the liver and kidney. The response of F embryos to added oxygen is the opposite that might be expected for aerobic metabolism. The reason that selection for growth has resulted in such a metabolism is unkno wn. The E embryos displayed depressed lactate and beta-hydroxybutyrate leve ls, but plasma urates were elevated compared with RBC1, suggesting that the selection for egg production has also resulted in a unique metabolism. The embryonic processes described in the current study suggest that selected e mbryos are unable to respond to elevated partial pressure of oxygen by adju sting energy metabolism, which may result in increased embryonic mortality during this stage.