Influence of yolk on blood metabolites in perinatal and neonatal chickens.

Abstract

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