Economics come into play, as well. Is the increase in cost justified?
Yes, normally, an 18% protein will provide them with slightly more where-with-all for feather production and egg production. Many folks prefer it. But the law diminishing returns comes into effect. 24% protein isn't going to produce even more and larger eggs, and so on.
A chicken needs a balanced diet for over all health. 16% layer feed provides them adequate, balanced nutrition.
If you are just wanting a good production of table eggs (as in to be eaten) then a balanced 15-16% layer feed will do that if it is fed as the sole ration. Not a lot of scratch, treats, or anything else other than free range and green feed.
If you want to produce eggs that will give you a good hatch rate of strong, healthy chicks then use a feed that is balanced in the 18-20% range.
More than 20% doesn't really get you anything that would justify the additional expense.
On the small scale in backyard flocks you may not notice much of a difference either way. As the flock size grows you'll begin to notice the difference.
Thanks for clarifying this, as I was wondering the same thing about the level of protien. This week I have to purchase my first bag of grower feed, now I will know what to look for in the protien levels in the different bags of feed.
Bumping the protein up in summer seems to help a little on production. The birds go off their feed some in the extreme heat so the higher protein seems to keep them better. By going to a higher protein they get the same amount of protein while eating less food overall. I have tried it and seem to see a little difference. I can get 22% Layer for $1.00 more than 16%. It seems to go a little farther so the cost works out about the same.
I do seem to have a better hatch rate using the high protein. I think Alan is right about that.