All 9 of my hens are 10 months. They are all different breeds - I got them all together as day old chicks from MyPetChicken last April 28th.
8 of them began laying at around 5 to 6 mos except for my Buckeye. At about 5mos she developed a lump on her face which turned into a spongy type lesion covering the right side of her face. She's had various tests - near as we can guess it could possibly be a lymphoma. Other than the swelling, she seems perfectly healthy - however she only started laying 2 weeks ago. Since then she is more bold, friendlier and more active.
Originally, I had started feeding layer feed when all 8 were laying, but then I realized it would be too much calcium for the Buckeye, so I switched to Flock raiser and offered oyster shells and egg shells.
Since the Buckeye started laying, i have switched back to layer feed.
They used to all mostly lay int the morning - but now I find some laying in the afternoon or even late afternoon. There are currently 6 nest boxes - of which they use 4.
Diet:
Nutrena Layer feed 16% crumbles
On very cold days, I boil up Quinoa and mix it into the dry food
Treats every couple of days are dried meal worms, kale, cauliflower, barley fodder, plain yogurt, boiled hamburger, scratch (I recently gave them canned crickets)
I change drinking water every other day - (2) 3 gal waterers with ACV or oregano oil or just plain
They are in a 10x10 coop and have a 12x16 enclosed run with a metal roof. Right now the run walls are covered in contractor plastic to keep out rain, snow, wind (not air tight, some areas are open)
They were all wormed in the fall and checked for mites. They have access to a dust bath, but only 2 of them use it.
I work at home so I am out there regularly throughout the day and I scoop all the time, so the place is pretty clean.
I can't really think of any health issues. I wish I knew who laid that egg.