I would chime in with Chris that the higher protein for adult layers produces healthier birds with better laying.
In winter I feed a 20% layer feed, while in summer I can cut back to 16% layer as the foraging is better on my limited range....even then, they tend to do better on a higher protein. Protein is also slower to digest which helps them generate heat in cold weather, another reason I feed higher protein in winter.
If you have lots of good range (translated lots of bugs and protein to be found), you can get by on lower 16% and save the money.
I do tend to be careful with my babies and keep them at 18% to no more than 20% protein so that I don't outstrip their growth, but I am growing heritage layer types. Commercial layers tend to do better on the higher protein (20%) as they grow quickly.
My Buckeyes were raised on 22% and at times I pushed that to 24% then cut back to 18%...but they have a lot in common with meat birds (how much protein is hotly debated for that breed). The Buckeye roos were processed a little early (16 weeks), but trimmed out at about 3 to 3.5 lbs. Another 4 weeks, pushing the higher protein, and I would have had the projected 5 lb to 6lb weight.
So if you stay with layer types, and have limited range, a higher layer protein can keep a stronger, healthier bird.
I personally tend to land on Nutrena's Feather Fixer year round. It has a nice 18% protein, a bit cheaper than the 20% protein feed here, nice calcium (bot not the highest content so I feel safe to feed my adult roos, bag says safe for adult roos). I offer calcite grit free feed for those who may need a bit more calcium.
I can easily get that vs. all flock which most places only want to carry in crumble in my area...and crumble, for me, is a total waste of money as it disintegrates to powder in no time in my Oregon humidity. I much prefer pellet after they are beyond the chick stage.
Edited by Lady of McCamley - 2/13/16 at 12:03am