Ive actually seen a fair amount in my old text books from the 80s saying pretty much double the figures you list at least for young birds and layers..but having horses, those are the 3 most important things to me after protein,fat and digestable fiber.. quickest way to a bad footed horse is not...
Pick up a poultry or even intro to animal husbandry book..i have 3 recipesin the onehave easy accessto,but all of mine are either 80s or early 90s and i dont know if there are better recipesnow..thhese are scientifically produced and discuss most commercial hatcheries use their own custom blends...