The goal of parasite control in cattle is to control losses to internal parasites at the lowest possible cost. The health and production effects of parasitism are related to the number of parasites in the animal. The number of parasites varies with the rate of exposure of the animal and its immunity to parasites. Losses due to parasites are generally reduced growth rate or decreased production of milk.
Death is an occasional outcome.
Problems with parasites are more common in the South. Parasite control is most cost-effective if the program is not based on the use of dewormers alone. It is difficult to make recommendations on parasite control without knowing about husbandry on individual farms. The adult worms of most problem species live in true stomach of cattle. These adult worms lay eggs which are passed into the manure.