prevalence of gastrointestinal nematodes in sheep (Ovis aries) in the central and south-eastern regions of Ukraine

The article investigates into the species composition of agents causing gastrointestinal tract nematodes in sheep. It determines the forms of nematodes communities. For this purpose, 710 sheep were examined, 79.58% of which were infected. The fauna of nematodes was represented by 15 species of helminths from 12 genera: Bunostomum, Oesophagostomum, Nematodirus, Chabertia, Cooperia, Trichostrongylus, Ostertagia, Haemonchus,.richuris, Aonchotheca, Strongyloides, and Skrjabinema. The indicators of infestation intensity in sheep ranged from 1 to 93 specimens per animal, and the abundance index ranged from 0.01 to 16.96 specimens per animal. The most common nematodes are H. contortus (prevalence, 61.97%), O. circumcincta (59.58%), T. colubriformis (57.35%), T.ovis (55.21%), N. spathiger (49.01%), Oe. venulosum (42.54%), S. ovis (41.13%), Ch. ovina (36.76%), and T. skrjabini (26.34%). Gastrointestinal nematodes in the body of 99.12% of the infected sheep proceeded as parasitic communities. Most frequently, coinvasions were represented by parasitic communities which consisted of five (prevalence, 14.51%), six (19.44%), or seven (15.92%) species. The study revealed 361 varieties of mixed coinvasions. The most frequent comembers were H. contortus, O. circumcincta, T. colubriformis, T.ovis, N. spathiger, S. ovis, and Ch. ovina. The data obtained provide an opportunity to increase the effectiveness of measures to combat and prevent gastrointestinal tract nematodes in sheep farms.