Apparently, some brands claim to contain a preventative not a feed through treatment. I can't imagine a feed with pesticides in it for chickens though. Mites usually attack the vent area. Have a look at lice and mites, you might just have a stressed bird. sure, poor nutrition could cause it. Scratch is very low protein. I personally wouldn't mix it. It's meant as a treat to encourage "scratching" and shouldn't be fed without grit (or tiny rocks and pebbles) to grind up the corn. You could toss some alfalfa hay, that is high protein and has some calcium too. The greens make for a beautiful yolk color. Meal worms are good but $$$.
