In nature, a mom hen will periodically adjust her eggs and rotate them throughout the day. When incubating, this exercise must be mimicked as much as feasible. Rotating makes it possible for the yolk to remain centered in the midst of the egg, in place of sticking to your shell. https://helixplanet.com/essential-dog-breeding-supplies-progesterone-testing-for-dogs-puppy-incubators-and-more/