This article presents the findings of a comprehensive scientific investigation into the morphometric parameters and allometric growth patterns of sterlet sturgeon (Acipenser stellatus Pallas, 1711) at four years old age group (n=298). The research was conducted under industrial fish farming conditions at Mozhaisk Experimental Fish Breeding Plant from 2013 to 2025. The primary objective of this study was to identify growth and development patterns of this valuable species currently threatened by extinction due to anthropogenic impacts and climate change in its natural habitats. The sample was divided into two subgroups (n=219 and n=79) based on size-weight characteristics to ensure greater accuracy and reliability of obtained data. During the study, detailed analyses were performed on key morphometric indicators including total body length, commercial length (from snout tip to base of median caudal rays), trunk circumference, distance from snout beginning to cartilaginous mouth arch, body mass, maximum body height, Fulton's condition factor, physical development index, and leanness index. It has been established that sterlet exhibits negative allometric growth, indicating formation of a slender body shape. This phenomenon is crucial for understanding adaptation mechanisms of fish to artificial rearing conditions and subsequent optimization of technological processes related to their maintenance and reproduction. Experimental data demonstrate significant influence of industrial cultivation conditions on morphological and physiological characteristics of sterlet. These findings can serve as a reliable basis for developing science-based strategies aimed at enhancing productivity and improving quality of cultivated products, as well as implementing urgent measures for preservation and restoration of disappearing natural populations of this species. Additionally, the paper discusses promising directions for further research focused on comprehensive examination of genetic and morphological factors influencing growth and development of sterlet within aquacultural production systems.

The aim of the research is to identify the features and differences in the signs of development of black-and-whiteheifers in the regions of Russia under the influence of various factors.

Materials and methods. The research was conducted on a sample of data on live weight (LW) and average daily gain (ADG) in first–calving cows born in 2009–2019 (n=74149) lactating in 32 regions of 6 federal districts (FD) of the Russian Federation. The coefficients of genetic correlation and heritability were calculated using a genetic covariance structure using a Limited Maximum Likelihood Estimation (REML) analysis of variance using the RENUMF90.

Results. When studying the variability of LW and ADG in different periods of heifer development, the LW of heifers turned out to be less variable, in contrast to their ADG. The coefficients of both genetic and phenotypic correlation indicate fluctuations from a weak to a very strong relationship between LW in different time periods of heifer development. Correlations of LW heifers with milk yield of 1 lactation in the period from 1—12 months. Their cultivars are positive, but the genetic ones are twice as low as the phenotypic ones (0,119—0,173 versus 0,207 –0,361). The difference between LW the number of heifers in the studied periods of their development in the regions of the Russian Federation is small, but there are significant differences in ADG. A consistent increase in the fat content of heifers of all ages was revealed at their later birth.

Conclusion. The analysis of fat production in different periods of heifer development and the level of productivity after the 1st lactation showed that with more intensive growth of heifers, their milk yield is higher. With a progressive linear increase in the LW of heifers, they lose ADG in different periods of animal rearing show abrupt changes with a sharp increase at the age of 10 months and a subsequent decrease at 11 months. Monitoring of monthly ADG can be used as a forecast of the level of productivity of cows after the 1st lactation.

Purpose: A regression analysis was used to study the relationship between age at first calving and lactation duration with first-lactation milk production indicators for subsequent consideration in breeding index modeling.

Materials and Methods. The study was conducted using the SELEX-Dairy Cattle information database from 18 breeding farms breeding dairy red cattle. Over 12 000 records of cows that comleted their first five lactutions from 2018 to 2023 were analised. The relationship between the characteristics was determined by calculating the regression coefficient in programm "Statistica". After determining whether the sample conformed to the normal distribution, milk production data from 10,284 cows were used in the calculation. The average milk yield of first-calving cows in the sample was 5,683 kg, with a fat content of 4,13 % and a protein content of 3,26 %. The first calving age in the sample group was an average of 32,2 month. The average lactation duration for cows that completed their first lactation was 359 days.

Results. The study showed that the age increase of the first cows calving age impacted negatively on milk yield over 305 days lactation period, reducing it by 25,4 kg per month based on average observations during 5 years. A decrease in milk fat yield by an average of 2,0 kg and milk protein yield by 0,3 kg was observed. The age of the first cows calving showed the most significant impact on cows dairy productivity, that completed their first lactation in year 2022: with a one-month increase in age at first calving, milk yield decreased by 110 kg over 305 days lactation period, milk fat yield by 6,6 kg, and milk protein yield by 3,4 kg. The age of the first calving of cows, that were under our examination, was more than 26 months, which significantly increases raising costs.

Objective: To determine the effect of the Russian-produced antioxidant MismaOx PF, added to complete feeds based on locally sourced ingredients (using the Republic of North Ossetia-Alania as an example), containing a subtoxic dose of nitrates, on the nutritional properties and environmental safety of cow's milk and its derivative.

Materials and Methods: Swiss cows served as subjects for the study. After the second lactation, 20 cows were divided into two groups of 10 animals, using the same principle as the other groups. Sodium nitrate was added to the feed of dairy cattle in both groups (at a rate of 0,03 g/kg live weight) to ensure a subtoxic dose of nitrates. To detoxify the analyzed toxins, MismaOx PF (RF) was added to the feed of animals in the experimental group at a rate of 200 g/t of feed. Milking tests were performed in the cows in the comparison groups every ten days. Average samples of milk and Ossetian rennet cheese were collected to study their nutritional value (chemical composition) and environmental safety.

Results. By introducing the tested antioxidant into the diet, lactating cows in the experimental group outperformed their control counterparts in dry matter content by 0,54 % (P<0,05), milk fat by 0,18 % (P<0,05), and protein by 0,23 % (P<0,05), including casein by 0,23 % (P<0,05). When feeding the antioxidant, lactating animals in the experimental group showed an increase in the proportion of α-casein in milk by 4,45 % (P<0,05) while simultaneously decreasing the proportion of the γ-fraction by 4,60 % (P<0,05). Under the influence of the denitrifying properties of the antioxidant, it was possible to achieve a decrease in the level of nitrates in milk by 2,50 times (P<0,05) and nitrites by 2,50 times (P<0,05); in cheese samples, nitrates by 2,65 times (P<0,05) and nitrites by 2,28 times (P<0,05).

The objective of this study was to determine the effect of the SorbiMix® sorbent on the growth of young cattle fed complete feeds based on locally sourced ingredients (using the Republic of North Ossetia-Alania as an example) with a tolerable level of T-2 toxin.

Materials and Methods. Swiss bulls served as subjects for the study. Twenty six-month-old bulls were divided into two groups (using the analog-pair method) of 10 animals each. The experiment and fattening period for the compared groups lasted 12 months. The feed for both groups included corn, barley, and soybean meal contaminated with T-2 toxin. To ensure the integrity of the experiment, these contaminated ingredients were mixed with other non-contaminated ingredients, ensuring that the mycotoxin content in the feed for the bulls did not exceed the tolerable level of 0.1 mg/kg. The experimental group animals were fed with 20 g of sorbent per animal. Nutrient digestibility coefficients and crude protein digestibility were calculated, and the phosphorus and calcium balance was studied.

Results. When the tested preparation was added to diets with a tolerant level of T-2 toxin, the experimental group bulls, compared to the control group, had higher dry matter digestibility coefficients by 3,11 % (P>0,95) and organic matter digestibility coefficients by 3,06 % (P>0,95). Including the sorbent in the diets during the metabolic experiment's recording period contributed to the average daily nitrogen retention of 41,26 g in the fattened experimental group young animals. In this indicator, the experimental group animals significantly (P>0,95) outperformed the control group by 5,04 g, or 13,91 %. In addition, the bulls in the experimental group also absorbed the macronutrients calcium and phosphorus better.

The study of the mitochondrial genome of Thoroughbred is of significant interest both for assessing the differentiation of the matrilineal structure of the breed and for finding genes that determine the performance of horses.

Objective: the aim of the presented work to study the variability of COX2 haplotypes in female lines of the Thoroughbred breed and their association with the racing performance of horses.

Materials and methods: genotyping of 40 Thoroughbred mares by mtDNA haplogroups and cytochrome c oxidase COX2A>G types was carried out by the Sanger method in the genetics laboratory of the All-Russian Research Institute of Horse Breeding. When identifying nucleotide sequences, data from GenBank were used on 17 nomenclature haplogroups placed under access numbers: JN398377-JN398457 and EF597513- EF597514. The results of sequencing the control region of the D-loop of mtDNA were analyzed in the Mega 12 program. When analyzing the COX2 sequence, the author's primers and the GenSeq reagent kit were used. The racing performance of horses was evaluated based on a set of indicators, including the total amount of winnings, the average winnings per race, the success rate, the distance of victories, and the best speed.

Results. Three variants of cytochrome c-oxidase COX2 were identified in the tested horses, with the presence of haplotype A in all female lines. Haplotype G was only observed in mares of L haplogroup. Thoroughbred mares with haplotype A had a more successful racing career compared to those with the A/G variant (P >0.05).

Conclusions.  The variability of COX2A>G gene haplotypes in Thoroughbred horses is associated predominantly with the L mtDNA haplogroup, which complements the information about the matrilineal structure of the breed and the mitochondrial genome.

Objective: to summarize scientific publications by Russian and international authors whose research included the use of short tandem repeat (STR) markers to study the genetic diversity of Cervus elaphus (red deer) followed by the selection of highly polymorphic microsatellite loci.

Materials and Methods. This analytical review article was based on scientific publications by Russian and international authors related to the study of Cervus elaphus, as well as official Russian internet resources. Publications were searched in open databases and library resources: PubMed (https://www.ncbi.nlm.nih.gov/), eLIBRARY.RU (http://elibrary.ru/defaultx.asp), and CyberLeninka (https://cyberleninka.ru/). The search was conducted using the following keywords: red deer, microsatellites, Cervus elaphus, STR markers, genetic diversity, red deer breeding.

Results. Amplification of 78 microsatellite loci was successfully conducted for red deer, which was confirmed by scientific publications. The following loci were most frequently encountered in the studies: BM4107, MM12, CSSM14, BM1818, CSSM19, CSSM22, CSPS115, HAUT14, ILSTS06, CSSM16, ETH225, and INRA35. Red deer has numerous subspecies within its taxonomy, and therefore, some STR markers may be absent from a given subspecies. To conduct microsatellite analysis of Cervus elaphus and its subspecies, we selected the following highly polymorphic microsatellite loci: BL42, BMC1009, BM4107, BM4208, BM888, BM4513, ETH152, RT13, RT1, INRA11, MM12, CSSM14, BM757, BM1818, CSSM19, CSPS115, HAUT14, BMS745, C229, T107, ILSTS06, C01, T26, T108, T156, T172, T193, T501, T507, Cel_007, CER14, CSSM16, CSSM66, ETH225, INRA35, INRA005, LSCV085, OarFCB193, RME25, CSRM60.

The objective of this study was to analyze the A/G polymorphism at position 17:453356000 in the TNS2 gene, its association with phenotypic traits in the Rofor rainbow trout individuals, and to investigate the structure of the size and weight characteristics within the examined sample.

Materials and Methods. The study involved two-year-old female rainbow trout Rofor breed (n=200), which morphometric data were collected, including body weight, total length to the end of the caudal fin, length to the end of the scaled body, head length, maximum body height, and body thickness. Genotyping was performed using a test system developed in our laboratory. Data analysis were provided in the R programming language utilizing the GGally package, as well as complementary analysis in Python using tools from the scikit-learn library.

Results. Two hundred female broodstock rainbow trout of the Rofor breed were successfully genotyped for the A/G single nucleotide polymorphism at position 17:453356000 in the TNS2 gene. The vast majority of individuals were heterozygous AG carriers (n=161). The study demonstrated a high interdependence among the morphometric traits of rainbow trout, with the GG genotype being associated with morphometric characteristics indicative of a larger body conformation. This research broadens current knowledge of rainbow trout genetics. Moreover, a genotyping test system for the A/G polymorphism in the exon region of the TNS2 gene was developed, offering a valuable tool for marker-assisted selection programs in rainbow trout breeding.

Objective: to study the development of the morphophysiological blood profile of young purebred Tashla sheep (first lambing) depending on age, as well as during the administration of a dietary supplement (DS) containing fatty acids and iodine.

Materials and Methods: the study involved 16 Tashla lambs, divided into control and experimental groups of 8 animals each. The animals in the experimental group received the DS at a dose of 1 ml/kg of body weight daily. The duration of administration was 30 days (from the day of birth to the 30th day after birth). The lambs received the DS individually. Blood samples were collected for clinical blood analysis (at 2 hours postnatal age, 7, 14, 21, 30, 60, and 90 days postnatal age). The clinical analysis included the following parameters: WBC (leukocytes), RBC (red blood cells), HGB (hemoglobin), HCT (hematocrit), MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin content), MCHC (mean corpuscular hemoglobin concentration), RDW (red blood cell distribution width), PLT (platelets), MPV (mean platelet volume), PDW (platelet distribution width), and PCT (platelet crit).

Results. The most pronounced changes with age were observed in lambs of both groups for WBC, RBC, HGB, MCV, and PLT. Significant differences in WBC, MCV, MCH, MCHC, RDW, PLT, MPV, and PDW parameters were observed after the use of the dietary supplement, primarily at 90 days of age. This indicates that the use of a dietary supplement based on fatty acids and iodine has a significant impact on the development of the blood system, particularly the erythrocyte and leukocyte components, increasing their values. Furthermore, it is possible to quantitatively assess the effect of the supplement on the development of the morphophysiological status of young Tashla sheep only after 90 days of age.

Objective: to analyze variation pulse patterns using mathematical analysis of electrocardiograms.

Materials and Methods. Electrocardiogram (ECG) and heart rate variability (HRV) parameters were studied in horses. The CONAN–4.5 software was used to analyze and record ECGs in the study animals. Clinical examination methods were based on B.V. Usha's clinical examination methods for animals and included inspection, palpation, percussion, and auscultation of the cardiac region.

Results. Based on the conducted studies, the following primary parameters of variation pulse pattern analysis were established during ECG analysis of horses: mode — 1,57±0,13 sec, mode amplitude — 43,63±3,19 %, variation range — 1,04±0,21 sec. Secondary indicators: index of regulatory systems tension of the body — 22,38±3,01 c.u., RMMSSD – 308.65±20.61 ms, pNN50 – 41.88±3.62%, index of vegetative balance — 35.75±9.39 c.u., vegetative rhythm indicator — 0,88±0,22 c.u., indicator of adequacy of regulatory processes — 23,51±2,16 c.u. Kaplan indicators – respiratory modulation index (RMI) — 9,51±2,56 %, index of sympathoadrenal tone — 62,01±3,83 %, index of slow-wave arrhythmia — 19,01±3,42. The cardiac stress index was 15,77±2,31 %, the cardiac arrhythmia index was 5,18±0,61 %. As a result of the conducted studies of the classical ECG analysis, the following average values ​​were obtained: P wave — 0,171±0,054 mV; Q wave — 0,212±0,071 mV; R wave — 0,275±0,104 mV; S wave — 0,424±0,153 mV; T wave — 0,140±0,038 mV. The duration of the R–R interval in horses is on average 1,558±0,131 ms and varies from 1,156 to 1,876 ms; the P–Q interval varies from 0,096 to 0,152 ms; The Q–T interval varies from 0,296 to 0,640 ms; the QRS complex varies from 0,022 to 0,064 ms.

Purpose: to identify antibiotic-associated behavioral disorders in white laboratory rats using an elevated plus maze and an open field. The work is aimed at establishing a possible correlation between intestinal microflora disorders and anxious or exploratory reactions of animals.

Materials and methods. The object of the study were six-month-old male and female white laboratory rats of the Wistar line breed weighing 400–410 g. Four groups of animals were formed, with ten individuals in each group: group No. 1 (males) and group No. 3 (females) were the control part of the experiment; group No. 2 (males) and group No. 4 (females) were the experimental part of the study. The animals of the experimental groups were given an antibacterial drug of the semi-synthetic penicillin group — "Amoxiclav". At the end of antibiotic therapy, feces from the litter were cultured. To assess the correlation of intestinal dysbiotic changes on the cognitive functions of rats, the "open field" and "elevated plus maze" methods were used.

Results. The study demonstrated that long-term use of the antibiotic Amoxiclav (0,02 ml/individual for 10 days) in white laboratory rats led to significant structural and functional changes in the composition of the intestinal microflora, which, in turn, was accompanied by stable behavioral changes. Against the background of microbiological changes in the open field test, rats from the experimental group (males and females) demonstrated a noticeable decrease in overall motor and exploratory activity. In addition to decreased activity, antibiotic-dependent rats showed signs of anxiety: the number of grooming episodes increased (in males). In the elevated plus maze test, the behavioral profile of rats from the experimental groups also corresponded to increased anxiety.

Conclusion. The results of the work confirm the hypothesis about the influence of the state of the intestinal microflora on the brain and prove that even a short course of antibiotics can cause stable behavioral changes through the mechanism of dysbiosis.

The aim is to determine the potential of rectal and ultrasound methods of ex-amination of cow ovaries in the diagnosis of follicular cystic disease.

Materials and methods. The object of the study is infertile Holstein cows of black-and-white breed, owned by Saryagash LLP (Republic of Kazakhstan). 58 ani-mals of 2-3 lactation were selected from 727 dairy cows for gynecological medical examination, the service period of which varies from 130 to 170 days. There are nu-merous unproductive inseminations and signs of anaphrodisia in the anamnesis. During gynecological medical examinations, clinical, rectal and ultrasound methods are used.

Results. Infertility in 79,31 % of cows is caused by follicular cystic disease, which has no specific clinical signs. Rectal palpation revealed pathology in 46 out of 58 cows; it is characterized by painless ovaries, the shape of which is rounded, the size is enlarged; the surface is smooth, but has rounded fluctuating elevations. The ultrasound method confirms the diagnosis in 30 animals. The cysts have clear boundaries, a thin-walled capsule and a size of more than 23 mm; they consist of two or three chambers with anechoicity. With ultrasound in B-mode, the size of cysts, the total area and area of cystic fluid, the total volume of cysts and cystic fluid average 3,30 cm; 17,05 and 26,30 cm2; 100,05 and 68,55 cm3; width of the luteal rim 0,10 to 7,00 mm. A comparative analysis of rectal and ultrasound diagnostics shows that the rectal method is less accurate, while ultrasound is more informative and less traumatic.