I'm still new at this so feel free to take my advice as you please. I've got 17, 3 week old Delawares. They've been on shavings since day 3 of arriving. Yes, sometimes they eat, or at least peck at, the shavings but they are all quite healthy and growing nicely.
I'm not sure about the RoosterBooster, ACV seemed to help my chronic pasty butt chicks more than anything. I also started giving them Yogurt on a plate sprinkled with feed for extra probiotics. I had 4 with pasty butt within a few days of arrival and 2 that had it chronic for about a week and a half. Have you seen them drinking? Dehydration can make pasty butt worse. I would dip my 2 chicks with chronic pasty butt's beaks into the water whenever I put them back in after a cleaning. Also, stress can be a factor for pasty butt. Are they cheeping loudly, high and sharp? That usually means something is wrong, could be too hot (which also increases dehydration), too cold, or possibly being handled too much. I struggled with myself over how often to clean the pasty butt because they get stressed when cleaned up but it has to be done. I cleaned twice a day, making sure they get warmed back up quickly after being wet. Folks say use a hair dryer on a low setting after cleaning to dry them off. I don't own a hairdryer so was using a small space heater. Are you cleaning with a cloth or holding under a light stream of water in the sink? I used a wet cloth at first but it took forever and was probably chafing their vents. A light stream of warm (not hot) water in the sink is way more effective and less stressful.
You can also try greasing up their little vent with either vaseline, coconut or olive oil, or a dab of original (not pain relieving) preparation H. Their vents can become swollen and the Prep H helps with that. Also, the oil or vaseline seemed to help things move a little easier. Good luck!
