As for chicks, no do not treat before they become sick.
The coop they live in has the cocy oosyt and they will come.
Generally the ooyst live were it is wet.
What I always did was put a piece of plywood 2ft by 3ft under,
the water and the water will soak in to the wood.
instead of wet bedding, which I one of their hiding places.
NOW HERE IT WHAT TO DO:
Watch every day a couple times a day:
FOR ANY BIRDS OFF BY THEM SELVS OR LOOKING RUFFLED UP.
They have coccidiosis.
immediately put corid 9.6%= 2 tsp per gallon of drinking water for 5-7 days.
When done medicating put 2 tsp of Bragg's unpasteurized Apple Cider Vinage per gallon of water.
Also do not feed medicated feed if you can still find it.
Some feed stores logged up on it when the government banned medicated chick fed.
But do buy good brand of chick starter like Purina.
Also check thedays as the vitamins will be dgone in it.ate on the tag of chick starter so as not to buy any that has a date of over 30 days.