oocysts per gram (opg) a count that was under 3,000 oocysts per gram (opg) of droppings was considered to be normal, with no expected response to treatment. A count of 3,000-20,000 opg was considered to be moderate, with treatment often providing a significant improvement in performance. A count of 20,000-50,000 opg was considered to be severe http://www.albertaclassic.net/chalmers2.php