Hickety Pickety (3 yo black sex link) lays every day, and her shells are so hard, you really have to smack them to get them to crack. I suspect she's still such a good layer because she's bred that way. My Blooper (light brahma) is quite the mature lady (I don't know for certain, but I'd say a good 5+ years). Last year she layed every other day-- sometimes 2 days in a row, but not often. her eggs have always been oddly shaped-- kinda long and pointy. She now only lays the occasional egg, but it's always soft on one side-- sometimes not so soft that it can't be used (I always use it the day it's laid if it's useable), but generally, it goes into the compost heap. They eat the same feed-- scratch, free choice layer pellets, and free range. I'm wondering if the difference could just be because Blooper is up in age? Maybe because Hickety is more of a "production" type and Blooper is not-- at least that's prob. the reason for her laying fewer eggs. I can see Hickety laying regular when she's Bloopers age. Also, the roos aren't interested in Blooper. We say she's just "yard decoration" anyhow. I've given extra calcium, but they don't touch it.
I was surprised to have one this morning from my 8 month buff orp. I haven't seen one out of her ever, so I don't know what conditions can cause it. She has oyster shell and layer pellets so it's not diet. Maybe its the weather, it has been crazy cold, raining and then sunshine, hail and thunder, every day is just nuts here so I'm blaming the weather for it. Hopefully it's not a sign of something else. Good luck with your girl.
I would be sure they get plenty of free choice oyster/egg shells. Older birds reqire more calcium from the stress of constant laying. I think a few high protein treats like black oil sunflower seeds and dry cat food would also make a difference. Light Brahmas are large hens and require a higher intake of good feed. bigzio