Population dynamics of gastrointestinal nematodes in organic sheep farms in Canada - First year

FERNÁNDEZ, ALICIA SILVINA; MEDEROS, AMÉRICA; SUDEMAN, ROBYN; BOND, ERIN; PEREGRINE, ANDREW; MENZIES, PAULA; VANLEEUWEN, JOHN; LEBOEUF, ANNE

Conferencia; 21st International Conference of the World Association for the Advancement of Veterinary Parasitology; 2007

Introduction: Little is known about the epidemiology of gastrointestinal nematodes in sheep in Canada and therefore how they can best be controlled. This research focuses on a three-year epidemiological study to monitor the levels of GIN in organic flocks as well as studying farm management practices that can be used to minimise parasite burdens. Method: The first year of this observational study started in spring 2006 on 32 farms; on each farm groups of 10 ewes and 10 lambs were sampled and evaluated every month (blood samples only at the beginning and August); pasture samples were also collected monthly; questionnaires were administered on each farm to collect information on every aspect of flock management practices. Materials: Parameters used were faecal egg counts, pasture larval counts, faecal cultures, worm burden of sentinel animals, PCV and TP, and animal scores (body, dag, faecal consistency, and FAMACHA) Results: Large variability in faecal egg counts and pasture infectivity were observed amongst the farms. Larval overwintering on pasture was detected in few cases. A third of the farms had to treat the flocks in mid or late summer due to clinical parasitosis. However, blood values were found to be within normal parameters. Conclusion: Research over the next two years will help to understand the factors associated with flock management in organic farms that contribute to lessen - or worsen -the incidence of GIN. Data generated will be used to develop models that can be used to predict the efficacy of different control programs on parasite control.