The aim is to test the method developed by the authors for assessing the genetic potential of multiple breeding in domestic pigs.

Materials and methods. The work was carried out on mini-pigs of breeding of ICiG SB RAS. Since it was previously established that the multiple fertility of sows of epistatic white color is higher than the multiple fertility of sows of non-white, the analysis of these groups was carried out through comparison.

Results. It was found that white sows have a higher fertility potential per piglet than non-white sows (15 and 14 piglets per farrow, respectively). That is, at first glance, the multiplicity potentials of the mini-pigs of the ICiG SB RAS are clearly excessive compared to the optimum. At the same time, the modal distribution class of the sample maxima of multiple fertility in white sows is 11 piglets in a litter, and 9 in non-white sows. The limits of the optimal number of piglets in a litter for mini-pigs of the ICiG SB RAS determined in one of the previous studies are min=8 and max=11 individuals. However, the average multiplicity of mini-pigs of ICiG SB RAS is 7,210±0,161 (white sows) and 6,560±0,117 (non-white sows) piglets per farrowing, which is less than half of their multiplicity potentials. Thus, despite the apparent redundancy, the fertility potentials of white and non-white sows should not be considered too large, since they are realized in less than 3-14 % of farrowing. Assessing the breeding value of sows requires knowing which number of offspring in a litter is normal for a given breeding group, and which is an emergency and should not be taken into account. The study showed that litters with fewer than 3 piglets should be considered emergency during the first farrowing. For subsequent farrowing, the minimum norm should be 6 piglets in a litter of white sows and 5 piglets in a litter for non-white sows.

The aim of the conducted research was to study the effect of the combined ac-tion of probiotic strains of microorganisms and the "protected" form of choline in the form of an innovative feed additive KPKh (probiotic complex, choline) on the milk yield and milk composition of Dorper sheep.

Materials and methods. The studies were conducted in the Department of Physiology and Biochemistry of Farm Animals of the Federal Research Center for Animal Husbandry – Academician L. K. Ernst All-Russian Research Institute of Animal Husbandry and in Voskhod LLC, Kaluga Region. The object of the research were two groups of ewes with 5 heads in each group. The groups were formed based on the principle of pairs of analogues: I - control, II - experimental. KPKh was in-cluded in the diet of the experimental group at the rate of 20 g per head per day mixed with compound feed. Milk productivity of ewes in the experimental and control groups was determined by the lamb gain in 20 days. Milk composition was de-termined using a CombiFoss FT+ device (FOSS, Denmark) based on infrared spectroscopy and flow cytometry (protocols recommended by the manufacturer were used).

Results. Thus, the use of KPH promotes an increase in milk productivity of ewes by 8.98 % compared to the control group, which is interconnected with both the improvement of digestive and metabolic processes, according to the available research data on the physiological action of both the microorganism strains included in the complex of enzyme-probiotic strains and the innovative form of "protected" choline. A significant increase in fat content (+19.8 % in the first month and +24.0 % in the third) was revealed in the milk of ewes in the experimental group, with an improvement in the fatty acid composition, as well as dry matter (+7.02 % in the first month and +9.07 % in the third).

The objective of this study was to analyze the key morphometric parameters of eggs from Russian White (egg) and Amrox (egg and meat) hens, which differ in their selection process.

Materials and Methods. The study was conducted on 34-week-old hens of the Russian White (n=26) and Amrox (n=22) gene pool breeds. The birds were housed in individual cages according to the farm's standard feeding and housing practices. The hens were evaluated for the following parameters on at least three consecutively laid eggs: egg weight (g), yolk size (g, %), PPF (º), elastic deformation (ED), and shape index (SI). Blood was collected from the axillary vein. The following parameters were determined: triglycerides (mmol/L), glucose (mmol/L), total cholesterol (mmol/L), creatinine (μmol/L), and total protein (g/L).

Results. Significant interbreed differences (p<0,001) were found in egg weight, shape index, protein fraction density index (PFD), and relative yolk size. Although Amrox chickens lay smaller eggs (egg weight is 10 % lower), their absolute and relative yolk content is higher than that of Russian Snow White chickens (by 4–6 %), which is also indirectly evidenced by a lower PFD value (by 4 %) and a higher PFD (+20 %). Blood biochemistry also revealed interbreed differences in the direction of metabolic processes in the poultry body. Thus, Amrox chickens have a 37 % higher (P<0.001) blood creatinine content and a 7 % lower total protein content compared to Russian Snow White chickens. The obtained data indicate that as a result of selection work on egg productivity indicators in Russian Snow White chickens, there was a significant decrease in the proportion of yolk in the egg.

Objective: to analyze the economically valuable traits of the Ayrshire breed by district of the Russian Federation.

Materials and Methods. The study was conducted using a sample of economically valuable traits for the Ayrshire breed, taking into account the districts of the Russian Federation. This sample was compiled using data from the Yearbook on Dairy Breeding in Farms of the Russian Federation as of January 1, 2024. The sample was compiled based on the location of breeding and by district of the Russian Federation. The study examined the number of Ayrshire cows, milk yield, average daily weight, average daily weight, live weight, age at first calving, and age at retirement.

Results. The Northwestern Federal District (NWFD) has the largest population of Ayrshire cows (20,400 head), and the majority of the herd is located on breeding farms (11,200 head, or 54.9 %). In terms of average milk yield for the entire herd and breeding farms, the best results were obtained in the Northwestern Federal District (7917 and 8862 kg of milk) and the Volga Federal District (VFD) (7996 and 8879 kg), respectively. Across the entire herd of cows, breeding farms, and breeding units, high values ​​of the mass fraction of fat and protein (MFF, MFP) in milk of Ayrshire cows were established in three districts: the Volga Federal District (up to 4.51 %; 3.60 %), the Central Federal District (CFD) (up to 4.42 %; 3.43 %), and the Northwestern Federal District (up to 4.31 %; 3.41 %), respectively. The highest age of retirement of cows (4.0 calving) was established in the Volga Federal District, which exceeds the Russian average by 0.9 calvings. Cows in the Northwestern Federal District have a higher age at calving (2.7) and a higher age at retirement (3.7). Due to climate conditions and animal breeding practices in each district of the Russian Federation, Ayrshire cows differ in numbers, productivity, and longevity.

Today, dairy farming is inextricably linked with the development of new breeding, genetic, and biotechnological approaches. In recent years, the use of Anti-Müllerian hormone (AMH) as a biomarker of embryo productivity and ovarian reserve has become particularly relevant in research. However, insufficient attention has been paid to studying the relationship between breeding value and the level of this biomarker in the blood.

Objective: to evaluate the correlation between predicted breeding value indicators in Holstein cows and AMH concentrations.Materials and Methods: First-lactation Holstein cows from a breeding farm in the Leningrad Region, selected as embryo donors (n=11), served as the study's sample. The study examined the correlation between predicted breeding value traits (64 selection indices), actual productivity, and AMH levels in the blood.

Results. A reliable correlation was established between AMH and milk yield (r=-0.68), metritis resistance (METR) (r=0.60) and fertility indices: pregnancy rate (DPR) (r=0.61) and duration of pregnancy (GL) (r=-0.84). Reliable correlations were noted between AMH and exterior indices: stature (r=-0.80), dairy form (r=-0.64), thurl width (r=-0.81), udder furrow (r=-0.72), rear teat placement (r=-0.64). Despite the sample size limitations of this study, preliminary conclusions can be drawn regarding the feasibility of determining AMH levels in cattle serum, along with other diagnostic tests, for animal selection.

Studying the qualitative changes in the sperm of young bulls that occur during the period of physiological maturation allows for a more accurate prediction of their reproductive abilities.

Purpose. To analyze the age-related dynamics of the qualitative (physical and biochemical) indicators of the sperm of young breeding dairy bulls. Materials and methods. The work was carried out at the breeding enterprise of JSC Nevskoye (St. Petersburg) in the period from November 2023 to April 2025. Groups of Holstein (n=25) and Ayrshire (n=12) bulls aged from 11 to 24 months were formed. Sperm production was obtained 2-3 times a week from conditionally healthy animals.

Results. The dynamics of sperm production indicators in dairy bulls aged 12 to 24 months showed the nature of reproductive function formation. There was a large variability in the average indicators, which is associated with the instability of spermatogenesis and the individual influence of the bull. The volume of the ejaculate increased by 1.8 times (p<0.05) in Holstein bulls and by 1.5 times (p<0.05) in Ayrshire bulls during the study period. The progressive mobility rate for Holstein bulls was 60–67 % at 13 months of age, while it was 36.2-49.7 % for Ayrshire bulls at 12-18 months of age. The quantitative indicator of spermatozoa in the ejaculate up to 14 months of age in all bulls was 3 billion/ml, further had a tendency to grow and after 19-20 months was significantly higher (p<0,05). It has been established that the period in which the produced ejaculate is suitable for cryopreservation in Holstein bulls is 14-15 months, in Ayrshire bulls it occurs somewhat later - in 19-20 months. With age, there is a tendency for the number of frozen quality sperm doses to increase - 51..54 at 12-13 months and 91..97 at 21-22 months. At the same time, the proportion of discarded ejaculate decreases - 46-57 % and 29-34 %, respectively, during the same periods. For Holstein bulls, the influence of the "age" factor was only observed on the average volume of the ejaculate (p<0.05). For the Ayrshire breed of bulls, the factor "age" had a highly significant effect on the volume of the ejaculate, the concentration of spermatozoa, and the activity of the sperm (p<0.001).

Purpose. To determine the effect of hormones circulating in the blood (somatotropin, thyroxine, triiodothyronine) on the body's ability of broiler chickens to increase body weight.

Materials and methods. In broiler chickens of the Smena 9 cross, raised in industrial conditions in a standard technological environment, the level of hormones circulating in the blood was determined: growth hormone, free triiodothyronine and thyroxine by ELISA at 14, 21 and 35 days of age, as well as body weight by individual weighing. To assess the statistical relationship between hormone concentration and body weight, the Pearson correlation coefficient was determined using the Exel software package.

Results. The concentration of growth hormone, free triiodothyronine, and free thyroxine during the rearing period of broiler chickens varies between 2,26±0,04—2,58±0,04 mIu/l; 7,01±0,02—11,10±0,03 pmol/l (p<0,05) and 12,92±0,08—14,18±0,07 pmol/L. Differentiation of individuals in the sample by body weight at 14, 21, and 35 days of age corresponds to a normal Gaussian distribution; with an average body weight of 531,0; 1025,0 and 2170,5 g, the proportion of broiler chickens with an approximate weight value in the sample is 85,00, 82,00, and 87,00 %. When assessing the correlations between the signs, it was found that in a pair of free thyroxine – body weight, the relationship is weak; in pairs of growth hormone – body weight and free T3 – body weight are r=0,44—0,48 and r=0,53—0.61.

Animal blood is one of the most important systems for assessing both the state of the organism as a whole and specific organs and tissues. Among all farm animals, rams are the most frequently used for model physiological and biochemical studies, especially for fistula experiments.

Objective: to assess blood parameters and physiological and biochemical status of Romanov rams (as model animals) before and after the use of an organic complex of chromium (III) with glutamic acid as a feed additive.

Material and methods. The balance experiment was conducted on Romanov rams (N = 3). The chromium complex with glutamic acid was added to the feed of the 1st and 2nd experimental groups in two doses (0.33 and 3.30 mg in terms of pure chromium). The duration of each experiment was 28 days. Before and after the experiment, blood was taken from the jugular vein for hematological and biochemical analysis.

Results. When using this complex, blood analysis of rams showed that homeostasis of its metabolites and formed elements is maintained at the normal level corresponding to clinically healthy animals. Significant changes in the content of urea in the blood: in the first experimental group - it increased more significantly (by 3.8%) than in the 2nd experimental group (by 2.5%) - relative to the control group, which is associated with increased metabolism of proteins and other nitrogen-containing substances in the blood, since urea is the final metabolite of protein metabolism in rams. This is generally a positive effect and is certainly associated with the inclusion of a chromium complex with glutamic acid in the diet of animals. Reliable differences were found for such indicators as the amount of hemoglobin and hematocrit (in the second experimental group it increased by 16.9% and 7.6%, respectively, compared to the control).

Purpose: to study the functional state of the liver in egg-laying chickens fed plant extracts with hepatoprotective properties in the Amur Region.

Materials and Methods. Three groups of 60-day-old Dekalb White egg-laying chickens were formed: a control group and two experimental groups, each containing 10–11 birds. Starting at 60 days of age, chickens in the first experimental group were supplemented with silimar at a daily dose of 0,01 g/kg of live weight. Chickens in the second experimental group also received silimar at the same dose and a saltwort extract at a daily dose of 0,05 g/kg of live weight. Chickens in the control group received only a standard diet. Live weight, clinical and biochemical blood parameters, and liver histomorphometric parameters were monitored at 60 and 90 days of age. Absolute organ weights were determined in 60- and 90-day-old chicks.

Results. Serum levels of the γ-globulin fraction of protein were found to be elevated in 60-day-old chicks by 50,8–64,2 %, AST by 3,3–3,5 times, ALT by 4,5–6,4 times, ALP by 4,8–6,0 times, and total bilirubin by 3,2–5,1 times. Glucose levels were decreased by 19,7–46,2 %. Microscopic examination of the liver tissue revealed foci of inflammation and isolated areas of fatty degeneration. After feeding plant extracts to 90-day-old chickens of the experimental groups, compared to the control group, the hemoglobin level increased by 11,4–23,3 %, albumin by 14,2–8,6 %, glucose by 18,0–18,4 %, the level of γ-globulins decreased by 21,2–27,5 %, and alkaline phosphatase by 22,1–29,4 %. Foci of inflammatory infiltrate persisted in the liver, but were smaller (100,0–150,0 μm in diameter) than in the control group (with a diameter of 1000,0–1250,0 μm). In the control group, foci of large-droplet fatty degeneration of hepatocytes persisted.

Purpose: to study the relationship between morphometric parameters of intestinal lymphoid tissue and anthropometric indicators (weight, body length) in young female Eurasian lynx (Lynx lynx).

Materials and Methods. The analysis included data from 12 individuals harvested during legal hunting and scientific shooting in 2023–2024 in the Kirov Region and adjacent regions. To study the intestinal morphometry of lymphoid tissue, small and large intestinal samples were used, in which the number, size, and spatial distribution of lymphoid nodules and plaques were measured. Anthropometric parameters (body weight accurate to the nearest 5 g, body length) were recorded before butchering.

The study results revealed a number of significant patterns. First, a general biological relationship between body weight and body length was confirmed (ρ=0,800, p=0,002). Secondly, a strong correlation was found between the duodenum area and body weight (ρ=1.000, p<0.01). However, negative correlations were also revealed: body weight was associated with a decrease in the number of lymphoid nodules in the duodenum (ρ=-0,800, p=0,002), while body length was associated with a decrease in the area of ​​the ileum (ρ=-0,800, p=0,002). Age-related dynamics of lymphoid structures in lynxes is manifested in a decrease in the number of nodules (ρ=-0,800) and plaques (ρ=-0,775) in the duodenum against the background of an increase in the distance between them (ρ=0,800). The species-specific characteristics of the lynx are reflected in the spatial distribution of lymphoid structures: in the jejunum, a positive correlation was found between the area of ​​nodules (ρ=0,800) and the number of plaques (ρ=0,632) and metabolic activity, which is characteristic of adaptation to an antigen load in the wild. Morphometric analysis revealed a structural reorganization of the lymphoid tissue: a decrease in the distance between nodules (ρ=-0.600) with a simultaneous increase in their number (ρ=0,600), indicating compaction and optimization of the spatial arrangement of immune structures. The predominance of lymphoid plaques in the duodenum (ρ=0,949, p<0,001) is similar to data for canids, in which they constitute up to 70 % of the lymphoid mass of the proximal sections.

Perinatal hypoxia is a significant problem that affects the development of the nervous system and subsequent cognitive functions in both humans and animals. In response to hypoxic exposure, the body produces trophic factors - neurotrophins, regulatory proteins that are synthesized in neurons and glia - NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor), GDNF (glial cell-derived neurotrophic factor). BDNF supports differentiation, maturation and survival of neurons, and also exhibits a neuroprotective effect under adverse conditions such as glutamatergic stimulation, cerebral ischemia, hypoglycemia and neurotoxicity. The goal is to study the dynamics of BDNF concentration in various brain structures of rats after exposure to acute normobaric hypoxia.

Materials and Methods. The work was carried out on Wistar rats of both sexes (20 sexually mature females and 10 sexually mature males, which were equally divided into 2 groups by the randomization principle and from which the offspring were obtained). Group 1 was the control, and the state of premature human pregnancy was modeled for animals of Group 2: the effect of acute normobaric hypoxia on rat pups on the second postnatal day and subsequently the dynamics of BDNF concentration in the brain tissues, frontal cortex, hypothalamus and hippocampus of rat pups was assessed by the enzyme immunoassay method.

Results. It was found that acute normobaric hypoxia leads to an increase in BDNF concentration up to 7 days after exposure to hypoxia in the whole brain, frontal cortex, hypothalamus and hippocampus of rats of both sexes, and then the concentration of neutrophin decreases to the physiological norm. During the experiment, the concentration of BDNF in the whole brain of females was significantly lower than in males, and in the hippocampus – vice versa.