INFLUENCE OF CLIMATIC CONDITIONS OF BESSARABIA ON THE EPIZOOTOLOGY OF INTESTINAL STRONGYLATOSIS OF SHEEP

The development of gastrointestinal nematode parasites of sheep depends significantly on the climate. Extreme heat and cold have a negative effect on the development and survival of helminth larvae, while an increase in temperature, within acceptable values, usually accelerates their development. Moisture is necessary for the development and movement of larvae from feces to pasture, so the amount of precipitation is a limiting factor for the transmission of infestation. Together, these factors determine the seasonal dynamics of sheep infestation, as well as geographic variation in epizootology. Thus, the effects of climate change are particularly important for the spread of parasitic helminths because of its potential to affect their free-living stages and their intermediate hosts. The purpose of the work: to find out the distribution of gastrointestinal parasites in sheep in the farms of Bessarabia, taking into account hydrometeorological conditions in 2023 and 2024. The main criterion during the epizootological survey of farms was the level of sheep infestation by nematodes Trichostrongylus colubriformis, Strongyloides papillosus, which parasitize in the small intestines, and Oesophagostomum venulosum, which parasitizes in the large intestine. In 2023, a total of 1,019 sheep were examined, and in 2024, 795 sheep of different age groups from sheep farms in Bessarabia. Helminthoscopy of faecal samples was performed using a modified McMaster technique with a minimum detection level of 20 nematode eggs per gram of faeces. The intensity of the invasion was determined using a quantitative helminthocoprological study (Stoll's method). Atmospheric precipitation is one of the least stable climatic factors, and at the same time, its volume and seasonal distribution in the south of Ukraine affect the distribution of gastrointestinal parasites in small cattle. According to the data of the hydrothermal coefficient, the climate of Bessarabia in 2023 was quite humid, while the climate of 2024 was characterized by severe drought. In 2023, the total infestation of sheep with strongylids was 40.8%, while in 2024 it was only 26.8%, which is 34.3% less. The maximum indicators of strongylidosis extensiveness in sheep were recorded in May 2023 during a period of sufficient moisture (65.5%) and in June (65.7%), when moderate drought conditions had set in, but a substantial release of helminth eggs (391.09±8.13 EPG) was still observed. In the dry year 2024, the peak infestation was recorded only once in April (51.7%) and a slight increase in September to 33.7% due to increased humidity. During the four dry summer months, the incidence of strongylids in sheep was at a low level of 19.1% to 24.5%.