I have 3 RIR hens that are getting on on years, I think about 4 or 5 years old now. Maybe thats not super old, but they are showing their age with bald spots and tatty tail feathers. I did not hatch them ,or care for them as youngsters, I kinda took them in as a trade/favor to a friend. As time has gone by, I have noticed them having bald spots on their heads and on their chests. NOT from being bullied or anything, I think its just age. NOT a mite, flea, or other infestation. No other hens have any issues, just these old girls. Their feather quality is poor, but they are a very healthy weight, not skinny or anything. I have been getting soft shelled eggs from 1 of the girls everyday. Is that something that just happens to older hens, or can I do something about it? I would love to hear some ideas as to special feed, or supplements I can give them to increase their health and longevity. My current feed regimine is- free-feed Flock Raiser, BOSS, Corn, Free range every day, fresh fruits and veggies EVERY day, some table scraps, Oyster shell, lay crumble is mixed in with flock raiser, meal worms once a week as a treat, boiled eggs w/shells mashed up with the egg once a week. Is there anything else I can do for these older girls?