INFLUENCE OF YOLK ON BLOOD METABOLITES IN PERINATAL AND NEONATAL CHICKENS

Two experiments were conducted to assess the role of the yolk sac duri ng the perinatal period (i.e., from embryonic Day 18 through hatch) an d until 15 days after hatching. Experiment 1 describes changes in seve ral yolk components. Approximately 70% of the yolk was absorbed during the perinatal period. Moisture, lipid, protein, and carbohydrate frac tions were all utilized during this period. In Experiment 2, the age a t which set-point physiological levels of several blood metabolites, a s well as the magnitudes of these levels, in deutectomized (DT) chicks (surgical ablation of the yolk sac within 1 hr post-hatch) were not d ifferent from non-DT controls. Results indicate that the yolk sac play s a central role in the hatching process of chicks, rather than servin g as a major metabolic reserve during the neonatal period.