Lime is Calcium Oxide (CaO). When it is exposed to water, it becomes hydrated lime or quicklime. It produces a lot of heat (that's why cement and concrete heat up after water is mixed in). The formula is CaO + H2O = Ca(OH)2 +heat energy. If a chicken were to consume lime, it would be subjected to a burning sensation in their throat. Remember, quicklime was used to hasten the decomposition of corpses years ago. I would not use it in the presence of chickens until after I had throughly watered it into the lawn, then it would probably be OK.