THAT is an excellent start. Strawberries are mostly water, good sources of vitamin C and magnesium, not a heck of a lot else.. If your chickens were given nothing but strawberry plants to eat, that would be a problem - the chickens would eat to imbalance, because they had no choice. Tommorow or the next day, you might offer some veggies (or peels), or a legume, or a near grain, or a grain, or a pulse. Variety. That will also help ensure that what might be imbalanced on one day averages out over time.
Or, you could not treat them at all. It isn't necessary, but it is satisfying.
and I should have done more research for my BSFL farm. Step one, don't use a black barrel (all I had). More shade would have helped too. possibly I started too small, as well (not enoiugh volume to moderate temperature changes? I've given it a lot of thought, but haven't come up with any satisfying answers.
Whatever you decide, I wish you every fortune in it.