Respiratory stuff keeps popping up in my flocks. Thought we had it licked by treating the affected pullets with Tylan, but now others are sick, mostly young pullets. Eyes matted shut, runny eyes and noses, slightly lethargic. I have Denagard 12.5% and from reading threads here, will start 16ml/gallon tomorrow, sweetened with sugar. I would like to treat the whole flock to try to stop this. Anyone have any idea how much sugar to add?