In my 2 main flocks of layers (15 and 20 hens and 1 rooster each) many of the hens have loose runny poop. Some of them look like they've gone cycling through mud puddles, they have brown stripes going vertically down their behinds. Otherwise, everyone is looking/acting/laying just fine. They are a mixed bouquet of large breed fowl, many mixed-breeds. Their ages are between 2-5 years old. I think it could be that some of them are just getting older, and their digestive systems aren't as perky as before. And/or because they've been living in the same yard for so long, that there are more cooties in the dirt that can upset their systems. We're in South Florida, where the whole yard is like a giant petri dish of microbes that never get frozen to death. I never see worms or anything like that in their poop. I am an avid poop inspector, these birds tell you more by what comes out of their butts than from their beaks. It's usually a normal color, not greenish or black, usually the regular brown, sometimes a brighter tan. So I am going to give them things that can supply beneficial bacteria to their guts. Today I gave each group a pan of pellets mixed with a quart of plain yogurt (with the live cultures). Next I plan to give them a pan of pellets wetted with water and some raw ACV. The waterers are galvanized metal so I can't put it in their water. What else could I give them that might help? How long should I wait between "treatments"? Should I wait a day or two between the yogurt & the ACV, or give them something like that every day? Thank you for your help & advice!