You can give 2 congealed teaspoons of unrefined organic coconut oil per chicken in a feed dish with some feed, and the fats in the coconut oil is a good source of fats for your chickens. Then as a preventative put a couple of tablespoons of apple cider vinegar in a gallon of water to keep them worm free, keeps the lice, mites, ticks, and fleas off them. It also keeps them healthy, and their immune systems strong so they wont get sick. Oh! And make sure that your waterer is not metal. Apple cider vinegar reacts to metal, and can poison your chickens. Must use plastic waterers. And the coconut oil, and apple cider vinegar both boost egg production as well. And you don't have to worry about chemical wormers tainting your eggs, and meat. Natural organic is the best, and healthiest way to care for your flock.