This article presents the findings of a scientific study investigating the efficacy of various assessment techniques used to evaluate the adaptability and productive qualities of Aberdeen Angus cattle on three prominent farms in the northern region of the Republic of Kazakhstan. A comprehensive analysis of the haematological and biochemical parameters of experimental groups of cattle with different genotypes (American, Canadian, and Estonian selection) was conducted. The studies revealed notable variability in haematological and biochemical indicators, contingent on the origin. Concurrently, the dynamics of the aforementioned indicators did not exceed the physiological norms. The modern allelofund was characterised with the help of microsatellite markers, and the level of genetic diversity of Aberdeen Angus cattle of different genotypes was estimated. The research uncovered the genealogical structure of the populations, the purity of the populations, the provenance, the polymorphism level, the heterozygosity indices, and the Wright fixation index (Fis). The genotyping of cattle of the Aberdeen Angus breed on 15 microsatellite markers yielded the establishment of 80 alleles in the Kolos-firm LLP, 77 alleles in the Vishnevskoe LLP, and 92 alleles in the Sever-Agro N LLP. The total expected heterozygosity was He = 0.673, while the observed heterozygosity was Ho = 0.710.

Background: A total of 396 samples were taken from the hearts, oesophagi, and diaphragms of 132 horses slaughtered at slaughterhouses in 2023 for subsequent examination. Methods: The histological method revealed pathomorphological changes in the muscle tissue. The molecular method identified the pathogen species. Results: Histological examination revealed thick-walled cysts with internal septa and numerous bradyzoites, and mononuclear inflammatory cells with pericyst infiltrates. Microcyst samples were amplified by polymerase chain reaction. Molecular genetic analysis allowed for the identification of 18 sarcocysts. Phylogenetic analysis of Sarcocystis isolates revealed three separate clades of Sarcocystis bertrami and two separate clades of Sarcocystis fayeri. Comparison and phylogenetic analysis revealed a very close relationship between the identified Sarcocystis species and other equine Sarcocystis DNA sequences from China and Japan. Based on the results obtained, the epizootic situation and the parasitic level of sarcocystosis contamination of horses in the northern Kazakhstan were determined. Conclusion: This is the first histological and molecular study to identify Sarcocystis spp. isolated from microscopic forms of equine sarcocysts in the northern Kazakhstan. This research will contribute to the fight against the spread of sarcocystosis in the Republic of Kazakhstan and will allow us to develop proposals for improving the mechanisms of sarcocystosis control.

В статье проведен анализ морфологических, биохимических и иммунологических показателей крови коров четырех мясных пород. Исследованиями установлена значительная изменчивость гематологических и биохимических показателей в зависимости от происхождения. При этом динамика исследуемых показателей не выходила за пределы физиологических норм. По результатам морфологического и биохимического анализа крови тестируемых показателей у опытного поголовья коров ангусской и герефордской породы находились на более высоком уровне по сравнению с аналогичными показателями калмыцкой и казахской белоголовой пород. Результаты исследований естественной устойчивости организма в разные годы акклиматизации показал, что достоверных различий между иммунологическими показателями у животных исследуемых пород не отмечается. Исследования выполнены в рамках научно-технической программы BR10764981 «Разработка технологий эффективного управления селекционным процессом сохранения и совершенствования генетических ресурсов в мясном скотоводстве» по мероприятию «Изучение заболеваний, ввезенного крупного рогатого скота мясного направления продуктивности и их адаптационных способностей с разработкой ветеринарных и зоотехнических мероприятий и рекомендации по их лечению и эпизоотическому контролю» программно-целевого финансирования Министерства сельского хозяйства Республики Казахстан на 2021-2023 г.

Background and Aim. At present there is no information about the prevalence of sarcocysto-sis among pigs in Kazakhstan, so we aimed to study pork meat for the presence of sarcocysts in the muscles of pigs in the Kostanay region. Materials and Methods. Pieces of heart muscle, neck, oesophagus, and diaphragm legs taken from pig carcasses served as material for the study. Sarcocysts presence in muscle slices was deter-mined by viewing the samples stained with methylene blue under a microscope. Morphological analysis of muscle tissues included histological and histochemical methods. Results. Muscle samples from 71 pig carcasses were examined. The intensity of sarcocystosis in pigs was 42.2%, and the intensity of invasion was 8.43 cysts. The highest infection with sarco-cysts was found in sows 3-5 years old (29.6%). The predominant sarcocysts localisation was found: in the heart - 23.9%, oesophagus - 12.7%, and the diaphragm legs - 5.6%. Cervical muscles from the same animals were free of sarcocysts. Sarcocystis suicanis species was detected Pathological chang-es in muscle fibres were detected in the examined muscle slices. Swellings and inflammatory pro-cesses of focal or diffuse character, as well as serous and less often purulent reactive myositis with infiltration and admixture of eosinophils or lymphocytes were noted. Examination of slices revealed an immuno allergic reaction leading to disruption of the heart histological structure, the oesophagus fibres and the diaphragm legs. Conclusion. Such animal muscles studies for sarcocystosis have not been conducted in the Kostanay region. The prevalence of infection from the number of the studied livestock were deter-mined. According to studies in animals, the infection prevalence increases with age, which is associ-ated with increased contact of pigs with primary hosts. According to the histological studies results, we have established inflammatory processes and muscle lesions caused by exposure to the product of parasite vital activity.

The review summarizes current data on the biodiversity of parasites of the genus Sarcocystis and their significance for ecosystems, veterinary medicine, and public health. Sarcocystoses are considered diseases of pronounced veterinary and zoonotic importance, as they lead to reduced productivity in farm animals, deterioration of meat quality, and may cause pathological effects in humans. Information on the taxonomic and geographic diversity of representatives of the genus, the specificity of intermediate and definitive hosts, as well as the influence of environmental factors on parasite circulation has been analyzed. It is noted that the actual species diversity of Sarcocystis significantly exceeds the number of morphologically described forms, which is associated with the active implementation of molecular genetic identification methods. Modern diagnostic approaches are reviewed, including morphological and histological studies, as well as molecular methods using markers such as 18S rRNA, cox1, and ITS-1, which make it possible to clarify taxonomic boundaries, identify cryptic species, and analyze phylogenetic relationships. The need to integrate classical parasitological and molecular methods to improve diagnostic accuracy, enhance monitoring, and develop preventive measures is emphasized. It is concluded that an interdisciplinary approach combining parasitology, epizootology, ecology, and molecular biology is essential, as it provides a deeper understanding of the evolutionary relationships between parasite and host and forms a scientific basis for the effective control and prevention of zoonotic sarcocystosis.

В статье представлены результаты распространения саркоцистоза собак и кошек в животноводческих хозяйствах восточной и западной зон Костанайской области. Ранее проведенными исследованиями образцов мышц крупного рогатого скота было установлено, что наиболее высокая экстенсивность инвазии отмечена в четырех районах области (96% и 100% соответственно), однако у коров в западной зоне и у бычков в восточной зоне отмечалась очень сильная интенсивность инвазии (от 207 до 279 цист). Копрологические исследования проводились в период с мая по июнь месяцы 2023 года. Были исследованы фекалии у собак и кошек отобранных непосредственно в хозяйствах с зараженным поголовьем крупного рогатого скота. Исследования фекалий собак показали 100%-ную их зараженность. Интенсивность инвазии в мае месяце варьировала от 10 до 27 экземпляров, в июне месяце в пределах 11…32 экземпляров в 1 грамме фекалий. В фекалиях кошек яйца паразита не обнаружены. Впервые изучены распространённость саркоцистоза у собак и определены взаимосвязь заражения промежуточных и дефинитивных хозяев в животноводческих хозяйствах двух районов Костанайской области.