I've been treating with oav also, not recently, but when I do treat, oav is what I use. The schedule I use is : first treatment is day zero, second treatment is day seven, skip treatment on day fourteen, third treatment is day twenty-one. Apparently this schedule takes into account and "covers" brood in all stages. When I put on my math thinking cap and draw some number lines (thank you Mrs. Crowder!) it does make sense. Mainly though, I follow that schedule because that's what LazyBkpr does. Ted