Your best chances are within the first 24 hours after ovulation, but there is still a small chance two days after. So, honestly, if your ovulation really did occur on the 18th then your chances aren't that great because you would be past that 24 hour window, but I wouldn't say its impossible.
Cryptosporidiosis. Cryptosporidiosis is a parasitic disease that affects quail, pheasants, peafowl, waterfowl, chickens, turkeys, finches and psittacines (such as parrots). Cryptosporidia are poorly host-specific and can affect other animal species including humans, other mammals,...
These pests can be a problem, particularly with smaller chicken coops. Chicken mite (chicken lice, chicken fleas, or chicken parasites) infestations can cause chicken or other fowl to look sickly or weaken their immune systems and lead to other chicken diseases.