They should be getting enhanced levels of Vitamins A, D, E, B₂, manganese and the amino acids cystine, methionine and lysine over what is in most layer feeds.
16% isn't sufficient for breeders. However, it is complicated as you will discover by reading the following.
Though uncommon, there are...
Temperature is the most important thing. To attain that, you need accurate thermometers. Either guaranteed accurate or calibrated. Without being as close to 99.5F as possible, all else makes no difference.
#2 most important IMO is fresh fertile eggs from hens fed a highly nutritious diet. Layer...