Correlation of body weight with hatchling blood glucose concentration and its relationship to embryonic survival

The negative correlation between selection for rapid growth and embryonic s urvival was investigated. Embryonic growth was assessed with hatchling weig hts of a closed population of commercial turkey breeders. Hatchling weights were highly significantly (P < 0.0001) and positively correlated with bloo d glucose concentrations at hatching. This relationship existed for both to m and hen poults. Significant differences among dams for hatchling blood glucose were observe d. Further experiments examined darns selected for producing poults hatchin g with high (High) or low (tow) blood glucose concentrations. The High embr yos were in larger-sized eggs with the same eggshell conductance but with s ignificantly lower conductance constants than the Low embryos, suggesting t hat Low had longer incubation periods. High embryos grew faster than Low em bryos with elevated organ glycogen concentrations. Organic acid analysis in dicated elevated plasma <alpha>-ketoglutarate, urate, and beta -hydroxy but yrate concentrations, suggesting a greater reliance on gluconeogenesis for the High group. Posthatch growth was significantly positively correlated with hatchling blo od glucose concentrations in toms but not in hens. Tom poults hatching with elevated glucose were heavier than low glucose hatch mates until 22 wk of age, but hen poults displayed no differences until 16 wk when High hens wei ghed less than Low hens. These data suggest that the negative correlation b etween rapid growth and embryonic survival is related to eggshell conductan ce constants and embryonic energy metabolism.