As chickens are kept outdoors they are fully exposed to wild birds that may be carrying agents that can weaken the immune system of your birds. Owners and keepers praise ImmunoTech Formula because they say it helps maintain optimal levels of body strength.
 
If one chicken is off colour you can use ImmunoTech on just the individual or one the whole flock for the sake of general nutritional safety. It is better to use preventative nutrition than to end up with less eggs and unhappy chickens.