Annual Dynamics of the Nosological Structure of Cattle Helminthofauna in the Amur Region

The aim of research is to study the characteristics of the helminth fauna of cattle depending on the season of the year. Every month, fecal samples were collected from cattle of several livestock farms in the Amur Region. Based on the results of the studies of the nosological structure of the helminth fauna of cattle in 2023–2024, the main circulating class of helminths was established: Nematoda (75.5 %) (Strongyloides papillosus, Strongylata spp., Neoascaris vitulorum, Trichocephalus spp., Mecistocirrus digitatus, Skrjabinema ovis). Class Cestoda – 20.4 % (Moniezia benedeni). Class Trematoda – 4.1 % (Dicrocoelium lanceatum, Fasciola hepatica, Paramphistomum spp.). The overall extensiveness of helminth invasion (EI) varied from 13.8 to 54.7 %. The maximum EI values were recorded in winter (January – EI = 46.2 %, February – EI = 54.7 %) and summer-autumn periods (August – EI = 47.8 %, September – EI = 52.6 %, October – EI = 49.3 %). The structure of the parasite profile changed in different seasons of the year, the most diverse species composition was in the spring – 8 species: Dicrocoelium lanceatum, Fasciola hepatica, Moniezia benedeni, Strongyloides papillosus, Strongylata spp., Neoascaris vitulorum, Trichocephalus spp., Mecistocirrus digitatus. The EI values also changed depending on the season. The basis of the nosological structure of the helminth fauna of cattle was made up of three constantly circulating species: Strongyloides papillosus (EI = 66.8 %), Strongylata spp. (EI = 5.9 %) and Moniezia benedeni (EI = 20.4 %). The average monthly infection rate of Moniezia benedeni was 5.4 ± 2.06 (p < 0.05), Strongyloides papillosus – 12.2 ± 2.26 (p < 0.001), Strongylata spp. – 1.1 ± 0.29 (p < 0.01). The seasonality of monieziasis has a clearly defined character, the seasonality coefficient (Sc) was 77.8 %, with the highest number of cases in February, May and October. The seasonality of strongyloidiasis is not expressed (Sc = 47.6 %). The incidence occurs in the months of seasonal increase (August, September, October). The seasonality of strongylatasis is moderately expressed (Sc = 69.2 %), the months of seasonal increase are February, March, June, August. In order to increase the effectiveness of antiparasitic measures, it is recommended to carry out not only planned deworming, but also deworming according to epizootic indications, taking into account the peak indicators of EI for the most common helminthiases.