I am a newbie to chicken keeping, and I have a few questions about coccidiosis and would appreciate any feedback y'all can provide. My chicks are currently 8 weeks old and have been on Purina Medicated Star & Grow since they hatched. They have never been vaccinated. I understand that medicated feed is useless if the chicks aren't exposed to coccidiosis, but how do I know if they've been exposed? They do have access to an outdoor run during the day. The run was grass but is now mostly dead grass and dirt. Chickens have never been in the run until I got my chicks 2 months ago, so I'm not sure if they have been exposed to coccidiosis. I do have lots of birds in my yard (mainly doves and jays). Here's my question: Is coccidiosis present is most dirt naturally, or is it only present in dirt that chickens have grazed on? Considering that wild birds have been in my yard, can I assume that coccidiosis is present in my dirt? Thanks in advance for any feedback.