Personally . . .
personally I don't think adding scratch to the diet as the chick matures is a bad idea. This is assuming that her commercial ration is a 20% protein or higher feed.
Eight weeks is really about the time that a bird gets a little more adventuresome with its diet. And, as a pullet approaches 16 weeks and older, her protein requirements can go down. That slows her development a bit but that's not necessarily a bad thing. Egg laying is tough business, she is almost all finished growing when that time arrives and it isn't such a bad thing for her to gain a little more size before putting out all the extra effort to produce eggs.
Of course, there are other foods besides scratch that would also be healthy and bring down the protein a few percentage points - if you stay on, say, a 20% protein feed right up until point of lay. Whenever you begin these non-milled products, however, the birds need to have
grit in their diets.
So, how much am I talking about?
Personally (again
), I shoot for about 15% of their diet in something other than commercial feed. This is also what many poultry scientist advise at the
top end for scratch. (A few say laying hens can have more, some say
zero scratch.)
Steve