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OSC Activity I.1

Over-wintering of gastrointestinal parasites in organic sheep production

Activity Researchers

Name Affiliation
Andrew Peregrine, Lead Researcher
aperegri@ovc.uoguelph.ca

Associate Professor
Ontario Veterinary College
Pathobiology
University of Guelph
Guelph, ON N1G 2W1

Paula Menzies, Collaborator
pmenzies@ovc.uoguelph.ca

Associate Professor
Population Medicine
Ontario Veterinary College
University of Guelph
50 Stone Road
Guelph, ON N1G 2W1

Jocelyn Jansen, Collaborator
jocelyn.jansen@ontario.ca
OMAFRA
Elora Resource Centre
Unit 10
6484 Wellington Rd 7
Elora ON N0B 1S0
John vanLeeuwan, Collaborator Professor
Epidemiology & Ruminant Health Management
University of Prince Edward Island
Atlantic Veterinary College
Andria Jones, Collaborator
aqjones@uoguelph.ca
Assistant Professor
Population Medicine
Ontario Veterinary College
University of Guelph
50 Stone Road
Guelph, ON N1G 2W1

Laura Falzon, Collaborator
lfalzon@uoguelph.ca

Graduate Student
Ontario Veterinary College
University of Guelph
50 Stone Road
Guelph, ON N1G 2W1

Objectives

To determine:

  1. Factors affecting over-wintering and periparturient egg rise (PPER) in ewes:
    1. Group level factors e.g. season of lambing.
    2. Individual level factors e.g. prolificacy.
  2. If strategic timing of anthelmintic treatment reduces PPER.

  3. Factors affecting the over-wintering survival of GIN including Haemonchus contortus on pasture under central Canadian conditions.

  4. If over-wintered L3 H. contortus larvae are capable of establishing a patent infection in naïve lambs.

Activity Summary

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 first – over-wintering in ewes - will be done by examining PPER levels in ewes under different management systems, specifically out-of-season lambing, how individual animal factors influence PPER levels, and the impact of strategic and limited use of anthelmintics in reducing this rise.  The effect of winter climate on survival of infective GIN larvae, including Haemonchus contortus, on pastures will be done by examination of presence of larvae on contaminated pasture plots.  One acre plots of pasture grazed that season by infected sheep will be assessed from the fall after animal removal until the spring before turn-out.  Micro-climate data will be collected using time-temperature-humidity recorders at ground and human height.  Presence and type of GIN larvae will be assessed by larval pasture sampling when not covered by snow.  Infectivity of present larvae will be assessed by spring grazing of naïve tracer lambs. This information will be used to develop a strategic integrated parasite control program for both organic and conventional sheep flocks in central Canada which will reduce level of disease, reliance on anthelmintics, and thus improve the productivity of this sector.