SEASONAL-VARIATION OF GASTROINTESTINAL NEMATODES OF SHEEP IN THE REGION OF JOANNINA, GREECE

Parasitological and growth studies on two groups of naturally infected sheep, with or without anthelmintic treatment, from the age of 3 mont hs to 2 years were carried out in the region of Joannina, Greece. A sp lit-plot design was used so that each group, consisting of seven pure- bred Boutsiko and seven cross-bred Boutsiko with Karamaniko (F-1) lamb s, grazed separate parasitologically equivalent pasture plots. Faecal egg counts, pasture larval counts, plasma pepsinogen levels and live w eight were recorded monthly. Infective larvae on each pasture plot inc reased during autumn and winter. Mean faecal egg counts for strongyle- type eggs were higher in the non-treated than the treated group and in the cross than the pure-bred sheep. Mean plasma pepsinogen levels wer e higher during autumn of the second year of the study. The results of the study suggest that the factors affecting the epidemiology of gast rointestinal nematodes of naturally infected sheep during grazing in t he region of Joannina include anthelmintic treatment, host genotype an d season, while the effectiveness of anthelmintic treatment in this st udy, as applied in the area, was questionable. (C) 1998 Australian Soc iety for Parasitology. Published by Elsevier Science Ltd.