So if a flock raiser is appropriate and won't put them at risk of being over weight, I'll consider switching them. They do free range 24/7 as well.
So flock raiser has more protein and less calcium than layer.. but your grower idea would be FINE also.. and there is NO risk of a chicken being overweight from being offered a formulated ration..
They eat to meet their energy need.. If flock raiser is higher in protein I presume layer is higher in carbohydrates which have the same calorie count, aka energy content. Most standard chicken feed don't include calorie count the way game bird, pig, dog, and cat food are clearly labeled. I THINK the chickens also likely have a crop capacity that they fill.. so most formulated rations will probably be done so meeting key nutrient requirements within a certain capacity..
Now somehow, the calcium in layer would almost be a filler for birds not in lay.. and it should have zero calories.. in my over thinking brain. And my birds do only go though .18-.20# feed per bird per day.. as compared to the .25# stated to be average. I realized part of this difference IS made up in the oyster shell on the side.
According to my understanding.. a calorie is a calorie is a calorie and there are only 2 sources of calories protein, carbohydrates including fiber, and fat. Birds who become overweight are likely offered excess amounts of treats and possibly genetically predisposed to it. I do NOT recommend it, but mentioning.. I have fed my birds 30% protein game bird starter with ZERO issues. And according to my research, 22% protein gave the highest hatch rates.. which also says more nutrients going into the eggs my family eats.. Sure they'll still be 34% protein and 64% fat with half the protein found IN the yolk.. but the micro nutrients matter.
But no, using a higher protein, lower calcium feed (does NOT have to be flock raiser, grower is also good) will NOT make your birds overweight! Their weight does fluctuate throughout the season and they can lose as much as 30% of their body weight during molt as the reproductive system shrinks back and such.
Having harvested my share of chickens.. even being the same breed on the same feed and the same age.. they have different size fat plugs and fat placements. Different maturity rates and different personalities.. Just like my siblings and I.. But if you'd like, there's no harm in getting weights on everyone.. tracking over time, say monthly, quarterly, etc.. Even do a body condition scoring test.. but don't forget to account for breed and age differences.. younger birds are bonier and awkward and some breeds are literally double breasted. From google..
They won't eat after dark, only freeloader will.
