OSC Subproject I: Sheep Parasites

Sheep parasite control

When sheep are raised on pasture they typically become infected with gastro-intestinal nematodes (GIN). Internationally, the sheep industry faces an increasingly severe production-limiting problem with resistance of the major species of GIN to all classes of dewormers. Because of this, sheep production has almost ceased in some regions. Thus, producers on conventional farms must adopt alternative control methods if sheep production is to remain sustainable. Similarly, since the sheep industry has embraced organic production, alternative methods must be adopted in order to prevent severe disease problems due to gastrointestinal parasitism.

In order to provide sound advice on alternative control methods, a thorough understanding of the epidemiology of GIN in Canada is required – unfortunately, no work has been carried out in this area in Canada for over 40 years.

This project will improve understanding of factors that affect two major sources of gastrointestinal nematodes (GIN) responsible for parasitic infections in sheep: over-wintering of hypobiotic larvae in adult ewes and the subsequent periparturient egg rise (PPER) which then contaminates spring pasture resulting in infection of naïve lambs; and over-wintering of infective L3 larvae on pasture from contamination from the previous grazing season.

The activity that makes up this subproject is:

• Activity I.1: Over-wintering of gastrointestinal parasites in organic sheep production