Contrary to what many people think, the infective larval forms of many internal parasites of sheep and goats can survive surprisingly well through the cold winters on typical pastures in Ohio. On-farm research conducted in the past few years at several locations in Ohio has reconfirmed that overwintered larvae can create heavy worm burdens in ewes and lambs, and this can result in severe disease as early as mid-June. In addition, adult animals can provide a new generation of infective larvae in the spring with the eggs they deposit on pastures in their manure.
In a 2012 fact sheet from Ohio State Universities, strategies for managing parasitism in the spring are discussed.
Read full fact sheet