What is the main function of the yolk in an egg?

The primary function of the yolk in an egg is to serve as the main nutrient source for the developing embryo. The yolk is rich in proteins, fats, vitamins, and minerals, which are essential for the growth and development of the embryo during the incubation period. It provides the necessary energy and materials needed for cellular processes, growth, and ultimately, the formation of various tissues and organ systems in the developing chick.

Other aspects of the egg structure play different roles; for example, while the albumen provides additional water and protein support, the shell offers protection to the embryo, but these functions are secondary to the yolk's nutrient supply role. Understanding this key function helps in both poultry management and the study of avian biology, as the yolk's composition can vary significantly between species and can impact the health and viability of the embryo.