For a 36-8 lb. hen that seems about right. Sure hope it is effective. Owing to our regular visitors (potential disease vectors) we are regularly adding more sand to runs (are well drained), they are raked out daily and we add garden lime - plain old crushed limestone in late winter/early Spring when the ground has gone `goopy' with the thaw. Regular worming schedule for chooks/turks. Our guys `range' but would rather hang out on covered front deck or near firepit than making the rounds around the pond or wandering out into the woods (excepting the hen's attempts at unauthorized nesting). I also keep up on the DNR's hunters' surveys that are compiled after each turkey hunting window (divided seasons) for all reports on diseased turks taken. Still nothing but Fowl Pox and foxes over the past 8 yrs., here. Early detection and immediate quarantine of any suspect turk is esssential owing to the speed and `efficacy' of lateral transmission.
Most comprehensive (free) bibliography (and other info) on Histomoniasis, that I've found, in turks: http://athenaeum.libs.uga.edu/bitstream/handle/10724/6287/hu_jinghui_200212_phd.pdf?sequence=1
