Oh wow! Thanks for that information. Glad I bought my egg turner now that I read this because I know I'd forget to turn them if I did it myself.Something ive read on the site glad to pass it along! I think i remember it is when their circulatory system, heart and brain and forming?
You might also appreciate the information that turning is most important day 4-14. As well as helping the circulatory system grow evenly it helps make the chick exercise. Weak chicks are one outcome of an unturned or under turned egg.