Generally I trust that the nutritionists at the feed companies have it figured out. If all you have in your flock is chickens that are actively laying, then a chicken layer feed would be appropriate product for your flock. I have the books Storey’s Guide to Raising Chickens (and Ducks), and both talk about how the nutritional needs of chickens and ducks vary and In different stages of their lives. If you have a more varied flock then you might need a different type of food. For instance if you have different types of poultry different ages of poultry young old male female you might need different feed. Also needs of broilers is different than layers.I have tried looking at the tags and online sources but most of it is chemistry to me. I do not know how much lysine and methionine a chicken, duck, or turkey is supposed to have or how much protein is to much for layer or to little for everything else, or if layers can have 18% protein, would I not get better results feeding an 18% feed and add oyster shell than the 16% layer that almost everybody has? (I am assuming that virtually all layer food has 16% protein for a reason.) Most of the advice I find talk about protein and calcium only or they give a recipe to make my own but nothing on how to decide beyond protein and calcium, how to choose one feed over another.