Over a few past decades, theoretical, analytical, and methodological advances in genetics have revolutionized population genetic research, providing a better understanding of evolutionary processes and the history of populations and species. Methodologically, this progress is largely due to the invention of polymerase chain reaction technology and the introduction of microsatellite DNA markers. This review discusses trends in the use of microsatellite markers as effective tools for solving a wide range of issues in population genetics, conservation and evolutionary biology of the only species of the genus Rangifer – reindeer. Based on the analysis of both experimental and review publications (78 sources) of the scientific teams of the Russian Federation, Canada, the United States of America, Ireland, Japan, China, Norway the first works on the successful amplification of reindeer microsatellites have been summarized. There has been demonstrated the significance of the data of markers for studying intra- and inter-population diversity, differentiation, genetic relationships, the impact of anthropogenic factors on genetic diversity and genetic isolation of populations, as well as for reconstructing the evolutionary history of the various reindeer forms.

The article provides the results of testing 13 soft spring wheat variety samples of the Federal State Budgetary Scientific Institution "Omsk ASC" in the competitive variety testing nursery in 2020–2022. According to the ripeness groups, characteristics is given according to phenotypic traits, resistance to leaf diseases and grain quality. Variety samples have been identified based on yield, stability factor (S.F.) and yield range (d), with weaker variability (CV), which exceed standards and are characterized by the highest level of realization of productivity potential. In medium-ripeness group the following variety samples have been selected: Lutescens 83/14-3, Lutescens 205/12-5, in mid-late maturity group – Lutescens 15/16-17, which ensure the formation of a consistently high grain yield, grain quality, and resistance to fungal pathogens, regardless of the environmental conditions. The parameters of ecological plasticity of variety samples according to grain yield were determined and the most adaptive ones in this set were identified – Lutescens 83/14-3 (b_i =1.16, S_d² = 0.02) and Lutescens 205/12-5 (b_i = 1.09, S_d² = 0.03). The obtained research results made it possible to transfer the cultivars ‘Omskaya krepost` 2’ (Lutescens 205/12-5) and ‘Omskaya krepost` 5’ (Lutescens 83/14-3) to the state variety testing. Using the PCR method, a genetic profile of the transferred cultivars was obtained using certain DNA markers.

Triticale is a versatile crop with high yield potential but insufficient resistance to unfavourable growing conditions. Therefore, the combination of high yield, adaptability, plasticity, stability and stress resistance of varieties is of great importance. The purpose of the research is to assess the adaptive potential of winter triticale cultivars according to the "yield" trait in agroecological conditions of the Middle Urals. Field studies were conducted in the Udmurt Republic in the years with contrasting weather conditions (2021–2023), the index of environmental conditions varied from -128 to 152. Forty-five cultivars of various ecological and geographical origin were studied. The analysis of the adaptive potential of the cultivars was carried out using various statistical methods. As a result, the most adaptive cultivars for the agroecological conditions of the Middle Urals were identified. The cultivars ‘Beta’, ‘Tribune’, ‘Topaz’, ‘Linda’ (Russia), ‘Mayak’, ‘Ales’ (Belarus), ‘Torchinsky’ (Ukraine) were char- acterized by high responsiveness to improving environmental conditions (b_i = 1.82 2.01). The cultivars ‘Giray’, ‘Bereket’, ‘Ataman Platov’ (Russia), ‘Amulet’ (Belarus) showed relatively high stress resistance. The cultivars ‘Beta’, ‘Zimogor’, AD 1405, ‘Topaz’, ‘Kornet’ (Russia) were distinguished by a high compensatory ability. The cultivars ‘Bereket’ and ‘Ataman Platov’ had the lowest yield variability and at the same time high homeostaticity. When ranking the tested cultivars according to the listed indicators, the top ten most stable and plastic cultivars were ‘Zimogor’, ‘Kornet’, ‘Ataman Platov’, ‘Bereket’, ‘Nemchinovsky 56’, ‘Izhevskaya 2’, ‘Imprint’, ‘Bard’ (Russia), ‘Impulse’ (Belarus), ‘Chernobrivets’ (Ukraine), with a total ranking score from 55 to 95 points. The listed cultivars can be classified as the most valuable. In the agroecological conditions of the Middle Urals, it is advisable to cultivate varieties that combine high yields and adaptability – ‘Zimogor’, ‘Kornet’, ‘Izhevskaya 2’, and according to intensive technology – ‘Beta’ cultivar. The cultivars ‘Ataman Platov’, ‘Chernobrivets’, ‘Bereket’, ‘Bard’, ‘Impulse’, ‘Nemchinovsky 56’ also have practical value as a source material in the breeding of winter triticale to increase productivity and adaptability. A comparison of different methods for determining the adaptability of cultivars to specific environmental conditions showed the practical equivalence of the indicators of yield range, yield variation coefficient and homeostaticity.

The breeding of winter rye for adaptability is an important factor in increasing yield and stabilizing gross grain yields.  The research was conducted in 2018–2023 in the central agroclimatic zone of the Kirov region. Thirteen cultivars of winter rye (Secale cereale L. var. vulgare Koern.) of the mid-late maturity group of different breeding periods (‘Falenskaya 4’ as standard) were studied in the nursery of competitive variety testing. Based on the “yield” trait, the parameters of the general adaptive ability of the cultivar (GAAi), stability (σ2SAAi), breeding value of the genotype, and responsiveness of the genotype to changes in environmental conditions (bi) were determined using the method of A. V. Kilchevsky and L. V. Khotyleva. The "year" factor had the greatest influence on the “yield” trait (the influence of factor h_x² = 60 %). With high winter hardiness (4.7 points) and plant regeneration (89 %), the yield of winter rye is associated with the amount of precipitation during the resumption of vegetation in April (r = -0.92), as well as during the period “seedlings-autumn tillering” and the “earing” phase (r = 0.55). According to the yield, the ‘Grafinya’ (5.09 t/ha) and ‘Lika’ (5.07 t/ha) cultivars were distinguished with a significant increase to the standard of 0.40 t/ha and 0.38 t/ha, respectively (LSD₀₅ = 0.24 t/ha). The ‘Grafinya’, ‘Lika’, ‘Batist’, and ‘Perepel’ cultivars had a high general adaptive ability (GAA_i = 0.23–0.51). Cultivars of late breeding periods were characterized by a higher general adaptive ability (GAA_i = 0.09–0.51) compared to previously created cultivars (GAAi = -0.61…0.01). The cultivars ‘Vyatka 2’,’Kiprez’, ‘Kirovskaya 89’, ‘Sadko’, ‘Grafinya’, ‘Batist’, ‘Rushnik’, ‘Perepel’ were distinguished by high stability of the "yield" trait (σ2SAA = 0.50–0.73). The lowest stability indicators were found in the cultivars ‘Flora’, ‘Lika’, ‘Talitsa’ (σ²SAA = 1.13–1.35). The cultivars ‘Flora’, ‘Lika’, ‘Talitsa’, ‘Falenskaya 4’, ‘Perepel’, ‘Rushnik’ were highly responsive to improving growing conditions (b_i = 1.1–1.4). The cultivar ‘Grafinya’ combined high yield and stability (selection value of the genotype 2.9).

In the forest-steppe of the Euro-North-East of the Russian Federation (The Republic of Mordovia), the research has been carried out to optimize methods for cultivating spring barley of the Zazersky 85 cultivar, which allow to increase yield and improve grain quality. The experiment was carried out in 2020–2022 on leached medium-humic heavy loamy chernozem. There were studied seeding rates (4.5; 5.0; 5.5 million germinating seeds/ha) and doses of fertilizers (Ν₀Р₀К₀; Ν₃₂Р₃₂К₃₂ – before sowing (background); background + Ν_30-60-90 – in top dressing). It has been established that increasing the seeding rate from 4.5–5.0 to 5.5 million significantly reduced the barley grain yield by 0.61–0.70 t/ha, respectively, on average over the years of the research. The crop yield increased significantly under the influence of mineral fertilizers – by 1.62–3.42 t/ha compared to the control (2.68 t/ha). In general, the highest grain yield (6.29–6.47 t/ha) was obtained when sowing barley at rates of 4.5 and  5.0 million germinated seeds/ha by the application of Ν₃₂P₃₂K₃₂ before sowing and Ν_60-90 as a top dressing in the tillering phase. Under the influence of fertilizers, the quality parameters of grain changed: the grain unit increased by 15–33 g/l, the weight of 1000 grains – by 0.63–1.53 g, the protein content – up to 13.2 %; the film content decreased by 0.3–0.7 abs.%. The highest grain uniformity (93.0–94.8 %) was observed at the seeding rate of 4.5 and 5.0 million germinated seeds/ha in the variants with nitrogen fertilizers (Ν_60-90) against the background of Ν₃₂P₃₂K₃₂. The highest profitability of grain production of the Zazersky 85 barley cultivar (103,18 %) was obtained at the seeding rate of 4.5 million germinated seeds per 1 ha with the application of Ν₃₂P₃₂K₃₂ before sowing and N₆₀ as a top dressing in the tillering phase.

In the period from 2016 to 2022 in the conditions of the Kirov region, an assessment of hybrid potato combinations was carried out according to the most important traits - high productivity and yield, marketable and consumer qualities of tubers. New potato hybrids bred by the Falenki Breeding Station – branch of the FARC North-East were used as the objects of the research: 6-17 (‘Gornyak’ x ‘Manifest’); 15-17 (428-05 x ‘Manifest’); 33-17 (132-07 x ‘Manifest’); 72-17 (‘Gornyak’בIrbitsky’); 78-17 (‘Udacha’ x 428-05); 120-17 (‘Utyonok’בReggi’); 25-16 (‘Kupalinka’ x 428-05). They were noted as the most promising ones according to the results of the research of 2016-2022. The medium-early ‘Nevsky’ cultivar approved for use in the Kirov region was used as a standard. According to the methodological guidelines of the potato breeding process, phenological observations, productivity assessment (on day 65), total and commercial yields were carried out in the nursery, and the chemical composition of tubers was determined. As a result, on average, over three years of testing for a complex of economically valuable traits, a promising breeding number 33-17 was identified – a significant excess of the total yield (29.9 t/ha) over the standard ‘Nevsky‘ cultivar was 14.6 t/ha. The tubers are oval with a red, slightly reticulated skin, the eyes are small, unpainted, the flesh is white. In addition, when evaluating the productive capabilities of potato hybrids, the coefficient of adaptability of breeding number 33-17 was 1.40, which makes it possible to recommend it for cultivation in this region in order to obtain stable yields.

The ultraviolet radiation (UVR) is the part of light spectrum sunlight and plays a very important role in plant biological processes. The use of ultraviolet irradiation can be a powerful tool for controlling pests and diseases of agricultural plants, as well as a tool for stimulating the synthesis of protective compounds, increasing the nutritional qualities and organoleptic properties of plants. Healthy meristem potato plants after transplantation into soil from in vitro conditions need optimal lighting conditions. In protected soil conditions, the use of additional ultraviolet irradiation of potato plants can significantly increase crop yield. To identify the optimal conditions for using this technique, it is necessary to study the reaction of different potato varieties to ultraviolet radiation. There has been studied the effect of UV-A (wave length is 360 nm, power density is 2.2 W/m2, time period between irradiation is 24 hours) for 10 days after transplanting regenerated plants of five potato varieties into soil. The effects on leaf area, over-ground and root parts, chlorophylls, carotenoid and proline content were investigated. Significant increase in aboveground biomass for ʻLuxʼ and ʻLegendaʼ varieties, root system mass for ʻLuxʼ and ʻAlyaskaʼ varieties, leaf area for ʻLuxʼ variety, proline content in ʻAlyaskaʼ, ʻIrbitskiyʼ, Terra varieties, and reliable decrease of photosynthetic pigments concentrations in the leaves of Legenda potato variety were revealed as affected by UVR. The results obtained correct the knowledge about the effect of UV-A on the growth and development of potato plants.

Grafting of vegetable crops is widely used in industrial vegetable growing in Asia and Western Europe. However, the influence of the genetic relationship of the scion and rootstock, the activity of peroxidase and the content of ascorbic acid in the components of the graft during inosculation period on graft survival has been poorly studied. The objects of the research are nine species of the pumpkin family (Cucurbitaceae). The polymorphism of 11 taxa was studied based on ISSR-PCR of genomic DNA. The record of survival rate of scion-rootstock combinations was conducted on the 10-th day. The activity of peroxidase was determined by the spectrophotometric method, the content of ascorbic acid was determined by Murri. Significant differences in survival rate were noted when grafting momordica into pumpkin rootstock variants: large-fruited (94.6 %) and nutmeg (67.1 %). In experiments with watermelon, melon and trichosanthes, the influence of the type of rootstock on the viability of the graft was not revealed. According to the ISSR spectra, the taxa were divided into two clusters; interspecific groupings of each clade were supported by average bootstrap values (from 26 to 100 %). A medium effect (r = 0.36) of the degree of genetic similarity of the scion with the rootstock on the survival rate of watermelon and a weak effect on the survival rate of melon, momordica and trichosanthes were revealed. The activity of peroxidase and the content of ascorbic acid in the grafting components in different scionrootstock combinations had a weak and moderate effect on plant survival, respectively. The survival rate of trichosanthes on various types of rootstocks strongly depended on the content of ascorbic acid (r = 0.7). Genetic relatedness, peroxidase activity, and ascorbic acid content had a weak or moderate effect on the survival rate of plants in scion-rootstock combinations.

In the conditions of the Sverdlovsk region (Middle Urals), a comprehensive assessment of elite forms of black currant was carried out to identify those suitable for mechanized harvesting with intensive cultivation technologies. The objects of research were 12 elite forms of black currant bred by the Sverdlovsk Breeding Station of Horticulture (planting 2018, layout 3×1 m). The research was carried out in 2021–2023 according to generally accepted methods. The studies were carried out according to generally accepted methods. According to the height of the bush, elite forms 3-2-05-08, 3-8-05-08, 5-2-05-08, 2-11-05-08 were distinguished – the measurement result was 100...110 cm; by the width of the bush – 3-1-05-08, 3-5-05-08, 3-8-05-08, 5-2-05-08 – 110...120 cm. The diameter of the base of the bush for most variety samples was 20.. 30 cm. The number of bent branches in all forms was less than 5 %, the diameter of the branches 8...15 mm. The average weight of berries was 1.5 1.8 g for elite forms 2-11-05-08, 3-5-05-08, 4-6-05-08, 4-7-05-08, 5-2 -05-08. The crushing force of berries in the studied variety samples was 201...367 g. Based on the force of berry separation, elite forms 3-5-05-08, 4-5-05-08, 5-4-05-08 stood out – 50 57 g. According to the results of the assessment of suitability for mechanized harvesting, the elite form of black currant 3-5-05-08 has optimal values in all parameters. Elite forms 2-11-05-08, 3-1-05-08, 3-8-05-08, 5-2-05-08, 4-6-05-08, 4-7-05-08, 5-4-05-08 are subjected to testing under production conditions. The following variety samples are not suitable for mechanized harvesting: 3-4-05-08, 4-5-05-08, 5-1-05-08, 5-3-05-08. In the conditions of 2023, elite forms 4-5-05-08, 5-1-05-08 were characterized by resistance to fungal diseases.

The purpose of the research is to identify the effectiveness of the use of various stimulating substances on the economic and biological parameters of plants of clonal apple rootstocks in the conditions of the arid zone of the Northern Caspian Sea (Astrakhan region). The objects were apple tree clonal rootstocks, scion and rootstock combinations. In the mother plantation of vertical layering, 10 breeding forms of rootstocks selected by various scientific institutions were studied. The control was the M series rootstocks, widely used and adapted in the south of Russia: M-9 for dwarf ones, M-26 for semi-dwarf ones, MM-106 for medium-sized ones. In a vertical mother plantation, there were studied variants for leaf treatments with Etamon Bio and Aminovit (control - treatment with water). Average for 2021–2023 foliar treatments significantly contributed to the high yield of first-grade rootstocks for rootstock forms 87-7-12 – 35.4 %; ‘Ural 8’ – 18.0 %; M-26 – 15.0 %; ‘Ural 5’ – 14.0 %; rootstock ‘Malysh Budagovskogo’ – 20.3 % in the variant with Etamon Bio treatment. In the variant with Aminovit treatment, the most number of first-grade layerings were obtained from the rootstock form 87-7-12 – 36.3 %; ‘Ural 8’ – 19.5 %; ‘Malysh Budagovskogo’ – 23.0 %. Foliar feeding with Etamon Bio and Aminovit had a positive effect on the length of the root system, an increase in the diameter of the trunk and an increase in the height of the rootstocks. In the first field of the nursery, the varieties were grafted onto rootstocks of varying vigor. The drugs for study were root formation stimulants Zircon; Ribav Extra; Kornevin. As a result, in comparison with the control, the survival rate of all rootstocks treated in the Zircon root formation stimulator was 100 %.

Data on productivity, fungal diseases and the quality of seed peas grown on sod-podzolic medium-clay soil in 2021–2023 using pre-sowing seed treatment separately and in combination with plant vegetation treatment with experimental preparations based on local strains of the genus Streptomyces (A4 and 8A1-3) are presented. The comparison drugs were the chemical fungicide Pioneer, KS and the biological drug Pseudobacterin-2, J. The assessment of the biological effectiveness (BE) of the drugs was carried out on cultivars of peas of various morphotypes bred by the FARC North-East: ‘Falensky yubileiny’, ‘Falensky usaty’, ‘Falensky kormovoy’. The biological effectiveness of all tested preparations in protecting peas from root rot and ascochitosis was determined by the weather conditions of the year of research. In 2021, a significant decrease in the development of root rot compared with the control (38.4 %) was facilitated by seed treatment with a preparation based on S. antimycoticus 8A1-3 strain (29.0 %). A significant reduction in the development of pea root rot in 2022 was achieved by seed treatment with the chemical fungicide Pioneer (by 9.1 %), the reference bio-drug Pseudobacterin-2 (by 9.9 %) and the test strain S. antimycoticus 8Al-3 (by 7.1 %). In protecting peas from ascochitosis in 2022, the strain Streptomyces A4 (BE 72.7 %) proved itself as a Pioneer chemical fungicide (BE 72.7 %), and the strain Streptomyces 8A1-3 (BE 84.1 %) significantly surpassed them in effectiveness. The effect of drugs on the yield of peas in the years of research (HTC = 0.77–0.83 with an average long-term HTC = 1.4) was estimated as insignificant. Treatment with both experimental and commercial preparations of seeds and vegetative plants did not adversely affect the grain size and the content of crude protein in it. The ‘Falensky usaty’ was distinguished among the studied cultivars by large seeds: the mass of 1000 grains was 258.8±18.5 g. The ‘Falensky kormovoy’ and the ‘Falensky jubileiny’ cultivars proved to be medium-seeded ones (174.7±23.1 and 147.9±37.1 g, respectively). The content of crude protein in grain was negatively affected by the development of root rot on peas (correlation coefficient r =-0.77). The maximum crude protein content was recorded during the joint treatment of seeds and plants with a preparation based on S. castalarensis A4 (24.0±2.6 %) in the ‘Falensky jubileiny’ cultivar, with Pseudobacterin-2 (23.1±2.0 %) in the ‘Falensky kormovoy’ cultivar, with a preparation based on S. antimycoticus 8A1-3 (21.1±1.7 %) in the ‘Falensky usaty’ cultivar.

Flood sedimentation in conditions of regular floodplain flooding is a key factor in the formation of alluvial soil.  The nature of the passage of hollow waters and their composition affect the quantitative and qualitative characteristics of flood sediments, while having a significant impact on the agroecological state of the floodplain agricultural landscape. The aim of the research was to study the role of flood sediments in enriching the underlying alluvial soil with nutrients. The experiment was conducted on reclaimed arable lands of the Ryazan region in 2023. Determination of the sediment load level and sampling on the surface were carried out using plastic sedimentation samplers fixed on the soil surface, located at a distance of 200 m from each other. The installation was carried out on March 23, the duration of sediment collection was 42 days before the descent of the hollow waters. The average sediment load level of 15.4 t/ha was established, the agrochemical properties of flood sediments and underlying soil were studied, the structure of organic matter, macro– and microelements with flood sediments and their removal from the corn harvest to silage was analyzed. Together with sediments the soil received (kg/ha): total nitrogen – 107.80, total phosphorus – 43.10, total potassium – 104.70, organic matter – 2464,0, mobile phosphorus 15.20, exchangeable potassium 17.80; trace elements (g/ha): boron – 11.86, molybdenum – 1.54, zinc – 122.74, manganese – 1215.06, copper – 200.20, cobalt – 52.05. With a corn harvest for silage of 36.1 kg/ha, the takeaway was: N – 105 kg/ha, P₂O₅ – 33 kg/ha,  K₂O – 105 kg/ha. The conducted studies indicate the undoubted agronomic value of flood sediments, they can partially meet the need for fertilizers, therefore, it is necessary to take into account the mass of the substances used to carry out appropriate adjustments to the fertilizer application system. In 2023, the mass of incoming substances with flood sediments completely covered the need for nitrogen; for mobile phosphorus the need decreased to 17.8 kg/ha, for exchangeable potassium the need decreased to 87.2 kg/ha.

The article presents the results of research of the influence of various cultivation technologies on the contamination of spring wheat crops and its yield for 2022–2023 in the conditions of the Nizhny Novgorod region on light gray loamy forest soil. There were studied the technologies various in methods of primary soil tillage (traditional, minimal – Mini-till, without tillage – No-till), and intensification level (basic, intensive). Spring wheat of the ʻZlataʼ cultivar was cultivated in the chain of rotation: clean fallow – peas - spring wheat. During the research period, it was established that the No-till technology contributed to an increase in the total contamination of spring wheat crops on an average for two years in the "tillering" phase (before herbicide treatment) to 36.2 pcs/m² (84.7 % higher than the total contamination of wheat crops when cultivated using Mini-till technology and by 118.1 % –using traditional technology) and in the phase of "full grain ripeness" (before harvesting) up to 30.1 pcs/m² (110.5 % higher than the total contamination of wheat crops cultivated using Mini-till technology and by 155.1 % according to traditional technology). It has been established that intensification of wheat production (application of mineral fertilizers in a dose of N₇₀P₅₀K₅₀ before pre-sowing cultivation; using fungicide and herbicide in the "tillering" phase) results on average among studied technologies in decreasing the total contamination of crops during the "full grain ripeness" phase on average for two years up to15.7 pcs/m² which is 38.2 % lower compared to the basic intensification degree of wheat cultivation technologies. It was found that the cultivation of spring wheat using traditional technology and Mini-till technology provides high yields: 3.09–3.43 t/ha, that is 0.63–0.96 t/ha higher than its yield when cultivated using No-till technology. There were no differences in the level of yield of spring wheat over the years of observation when cultivating it using traditional and Mini-till technologies. The intensification of spring wheat production makes it possible to increase the level of its yield for each of the studied technologies.

Agricultural producers are increasingly using plant-based feed additives in the diets of livestock and poultry as a way to increase animal productivity and stabilize the protective functions of the body. The purpose of the research was to study the effectiveness of using Astragalus cicer feed supplement in the diets of laying hens of the Lohmann Brown-Light cross at the age of 25-51 weeks. The composition of the compound feed included a phytoadditive made from Astragalus cicer in the volume: I experimental group – 3.60 %, II experimental – 7.20 % by the weight of the compound feed. The duration of the scientific and production experiment was 183 days. The analysis of the content of biologically active substances in the Astragalus cicer phytoadditive has revealed a high content of dihydroquercetin – 336.25 mg/100g of absolutely dry substance.image As the result of the research, it was found that laying hens of the II experimental group, which received 7.20 % of Astragalus cicer phytoadditive in the compound feed, had more intensive metabolic processes in the body, which contributed to obtaining a greater effect from them. Laying hens of the II experimental group compared with the control and I experimental groups had 2.19 and 2.18 % higher values of nitrogen utilization out of taken feed, egg production was higher by 2.81 and 1.10 %, the cost of compound feed decreased by 10 pcs. eggs, that was by 4.76 and 2.38 %, respectively. The profitability level of egg production in the II experimental group was higher compared with the control and I experimental groups by 3.83 and 5.16%, respectively.

The article presents studies on comparison of the levels of precocity and milk productivity indicators of the daughters of Holstein bulls, who are evaluated for the quality of offspring simultaneously in two breeding plants of the Moscow region. According to the official ratings of breeding values, the bulls were divided into groups of "improving" and "worsening". The ratio of the daughters of the "best" and "worst" breeding bulls was 511:568 and 160:127 heads over the farms. It was determined which values of the differences in the "daughter – mother" indicators were increased in groups of officially evaluated bulls that received ratings of "improvers" and "deteriorators" according to the characteristics in these two breeding plants. The bulls being tested were fixed individually, and according to the number of pairs as the main ones. At the first insemination, the daughters of the "improving" group of bulls had 6.5–8.5 kg increased live weight of, but were relatively older by 0.36–0.6 months. According to the milk yield trait, the total yield of milk fat and protein, highly rated fathers in breeding plants were significantly inferior to competitors with low breeding value in milk yield by 688–1136 kg, according to the difference "mother – daughter" in the total yield of milk fat and protein per lactation – by 43.1–97.3 kg. In one of the farms, the "daughter – mother" differences in milk yield in all bull clusters increased by 599–1275 kg of milk; according to mass fat fraction (MFF) — by 0.02–0.20% and for mass protein fraction (MPF) — by 0.19–0.31%; in another farm, the increase in milk yield was by 43.8–1551 kg of milk and 0.05–0.13% according to the MPF. The daughters of the "worst" fathers in terms of MFF and MPF significantly outperformed the group of daughters of the "best" fathers in terms of "daughter–mother" differences by 35.6 and 61.7 kg of total milk protein and fat output over 305 days of lactation. At the same time, there were no significant differences between daughters and peers. The relativity of the official definition of the values of the breeding value of breeding bulls has been proved. It is proposed, regardless of the "commercial" and previously conducted estimates of breeding bulls, to take into account the indices of pedigrees and types of selection when breeding them. Conclusions are drawn about the significant influence of the factor and selection methods on the values of milk production traits; in order to save growing costs, it is proposed to optimize the live weight and age of insemination of heifers in farms.

In veterinary medicine, treatment of wounds is one of the most important areas. A possible way to solve the problem of wound treatment is to activate the body's own protective reserves, primarily the immune system. Various immunostimulants and immunomodulators are widely used to activate the immune system. Known immunostimulants are derivatives of pyrimidine bases, in particular, potassium orotate (potassium salt of orotic acid). Orotic acid is found in milk and colostrum of animals. The use of orotic acid or its salts as immunostimulants is difficult due to their low bioavailability determined by their solubility in water. It is possible to increase the effectiveness of immunostimulators based on potassium orotate by including it in liposomes. Liposomes with encapsulated potassium orotate were obtained by shaking. The aim of the research was to study the activation of immunity macrophage link by liposomes with encapsulated potassium orotate. Evaluation of the effectiveness of the liposomal drug was carried out on rat wound models and on post-castration wounds of suckling pigs. Animal experiments were conducted according to bioethical norms. Complete wound healing in rats with the use of liposomal gel occurred on day 2, earlier than in the control with the use of Monclavit-1, while in the experimental group, compared with the control group, the content of leukocytes, lymphocytes, monocytes, platelets and granulocytes was significantly higher. The healing of surgical wounds in piglets after castration with the use of liposomal gel occurred 2 days earlier than with the use of the drug "Monclavit-1". There were no complications in both groups. Based on the analysis of literature data and the results of our own research, a scheme of the mechanism of action of a liposomal drug was proposed. The hypothesis about the mechanism of influence of liposomal composition on the macrophage link of immunity has been presented.

The purpose of the research was to study some indicators of antioxidant and hormonal status in the body of ewes and young sheep of the Romanov breed, as well as to identify correlations between the studied indicators. The experiment was carried out in the physiological yard of the L.K. Ernst Federal Research Center for Animal Husbandry in spring of 2022 with stall housing, on 2 groups of ewes (30 days, n = 15 and 90 days after lambing, n = 14) and 3 groups of young Romanov breed (aged 1, n = 15, 3, n = 14 and 4 months, n = 13). Indicators of antioxidant and hormonal status were determined in the blood. Mathematical and statistical processing of the results was carried out using methods of descriptive statistics, one-way analysis of variance, and correlation analysis. The high level of total antioxidant status in the blood of ewes 3 months after lambing (2.38 mmol/l) indicates successful adaptation to oxidative stress and LPO accumulation through the use of enzymatic and non-enzymatic antioxidants. In the blood of lambs upon weaning, the maximum accumulation of TBA-AP is observed compared to animals at one month of age (3.49 versus 3.21 μM/l at p≤0.05), which is compensated by the body by increasing the level of ceruloplasmin and catalase number. At an older age, the body shows adequate adaptation to post-weaning stress, which is manifested in a decrease in the level of TBA-AP by 24.93 % (p≤0.05), an increase in the concentration of ceruloplasmin, a decrease in peroxidase activity (by 28.47 % at p≤0.001 and 8.13 %, compared with the age of 1 and 3 months, respectively), increasing the TBA-AP/CP ratio. The acquired knowledge about age-related and physiological changes in LPO, AOD and hormonal status will be useful in assessing the health status and will help to provide timely preventive measures that increase the adaptive capabilities of the sheep’s body and the fullest realization of the genetic potential of productivity.

The purpose of the research is to substantiate the critical rotation speed of a rotor with bent blades based on force analysis and modeling the movement of mixture particles in a horizontal loader of a circulation mixer. The research method[1]ology included the substantiation of the highest rotation frequency of the loader blade rotor based on a force analysis of moving particles of forces when they were moved by the bent blades of the loader and compliance with the conditions for the entry of flying particles into the tray. The numerical analysis performed on the basis of the obtained expressions using the Mathcad mathematical package made it possible to establish the critical values of the rotation speed of the rotor-loader with bent blades based on the condition of the material coming off the blade and the condition of the flight of particles from the blade into the receiving tray. With radial blades, the limitation is the entry of particles into the receiving tray at a critical frequency of 43 min^-1 , then for a blade bend of 30° – about 60 min^-1 , for a blade bend of 45° – about 70 min^-1, for a blade bend of 60° – about 80 min^-1. The lowest critical values of the rotor-loader rotation frequency from the condition of particle movement along the blade correspond to the blade bend angle of 27–60° and are determined by the friction coefficient of the material, amounting to 83–78 min^-1. With an increase in material friction, the critical values of the rotor rotation speed from the condition of material coming off the blade decrease slightly, and the bend angle for the rotation speed extremum increases. The highest rotation speed of the rotor - loader with a radius of 0.12 m is limited to 78 min^-1 at a blade bending angle of the order of 30–60°, determined by the friction of the material on the blade.

The article considers the issues of using a propeller apparatus for mixing semi-liquid feed mixtures in a mixer with an eccentrically positioned working body in the form of a propeller (screw). Until now, when studying the mixing process, little attention has been paid to the transporting ability of the working body in the form of a propeller agitator. When preparing wet mixtures, agitators with a vertically positioned shaft, which is located in the center of a vertical cylindrical tank, are widely used. When installing the working body horizontally, the propeller having a pumping effect (axial movement), can be used not only for mixing, but also for unloading the finished feed mixture, as well as moving it through pipes over short distances. The existing models of the mixing process do not take into account its stochastic nature. Methods of mathematical description of mixing processes considering the prevailing axial movement of the flow are scarcely developed. The proposed mathematical models make it possible to determine the mixer's performance and the required mixing power. The research was aimed at increasing the effectiveness of preparing a feed mixture in a horizontal mixer of propeller type with an eccentrically positioned working body (screw) and saving energy costs along with raising the productivity. The object of the study was a mixing chamber with eccentrically located working bodies of various diameters (0.2, 0.25 and 0.35 m). During the experiments, the productivity required to drive the motor shaft was determined. It has been experimentally established that increasing the agitator rotation speed from 200 to 400 min-1 with a propeller diameter from 0.2 to 0.35 m and a feed mixture humidity of 84 % leads to an increase in power consumption to 3.5 kW and mixer productivity to 12 m3/h, and the degree of uniformity of feed mixtures is up to 98 %.

The article examines the little-studied issue of seasonal employment in the agricultural economy as a vector of the employment category, the importance of which increases every year. In this regard, the purpose of the study is to develop proposals for improving state regulation of social protection issues for seasonal workers in agriculture. The long-overdue issues of regulating the labor relations of Russian agricultural producers with workers employed for seasonal work in terms of social guarantees require timely solutions. Also on the agenda are the acute problems of providing basic living conditions for the employees involved, especially with regard to housing conditions, transport and telecommunications infrastructure. As of the end of 2022, only 72 % of rural settlements have paved roads connected to the public road network, and the proportion of households in rural settlements with Internet access amounted to 81.2 %. The scientific novelty of the research consists in the development of specific measures of state participation in the development of basic rural infrastructure and the creation of favorable living conditions for seasonal workers in agricultural production. In particular, measures are proposed to stimulate the involvement of seasonal workers with the prospect of improving housing conditions. The use of the mechanism of concession agreements in terms of the development of transport infrastructure and the application of proven foreign practices in the development of telecommunications infrastructure, taking into account the consolidation at the legislative level, will allow the most effective use of the workforce of seasonal workers in the agricultural sector.