Yolk sac absorption and initiation of growth in broilers.

A series of three experiments was conducted to determine the role of the yolk sac in initiation of growth in broilers. In Experiment 1, absorption of the yolk sac was found to precede initiation of growth in newly hatched broilers by approximately 24 h. Because the yolk sac is essential for early initiation of growth, in Experiments 2 and 3 it was removed and diets with incremental fat levels of 3, 6, and 10% were fed to assess whether fat was essential for optimal growth during the neonatal period. Results suggest that dietary fat has its greatest effect on growth after 10 days of age. Therefore, initiation of growth may be more closely dependent upon other nutrients.