My old hen finally started laying at 49 weeks. Ironically, I think she had some kind of low-grade respiratory infection that was preventing her from laying. I saw her sneezing for a couple of days, so I treated her with Tylan + Oxytetracycline for 7 days. On day 5 of her treatment, she laid her first egg. Perhaps it was just a coincidence, but now I'm wondering if late layers have something else going on regarding health.