Mold fungi and the mycotoxins they produce have invariably accompanied humans, since the basis of its existence was agriculture, which allows to get more products than was necessary for consumption, as well as requiring the storage of crops between seasons. This provided a favorable ecological niche for molds, and stored agricultural products became the main source of mycotoxins in the diets of humans and farm animals. Since then, mycotoxins have been the cause of many large-scale poisonings and have caused significant damage to agriculture. The article provides a brief historical sketch and the most significant stages of the study of mycotoxins, which are the cause of frequent and large-scale lesions, reveals the specific circumstances that caused the researchers' keen interest in this group of substances. For a long time, the immediate cause of poisoning caused by mycotoxins remained unknown due to the weak technical equipment of researchers and the isolation of active substances was impossible, which, however, was not an obstacle to the development of methods to combat infection with mold fungi and poisoning caused by mycotoxins. The improvement of the technical base of research in the middle of the 20th century led to an increase in the number of discovered mycotoxins and the discovery of new toxic effects of already known compounds. Mycotoxins remain one of the most dangerous contaminants in both farm animal feed and food, despite the fact that in many countries they are subject to strict regulation and control. In the context of the increasing intensification of agriculture, a decrease in the species diversity of agricultural crops, the problem of the spread of mold fungi and, as a result, the degree of mycotoxin damage to agricultural products does not lose its importance, and the study of the history of the study of mycotoxins and their producers can provide important information on the spread of mold fungi in new economic conditions.

During the years with acute epiphytotic conditions, infectious diseases of plants cause significant crop losses. To ensure the productivity of agricultural crops, pesticides are used, that is, substances of chemical nature that protect plants from phytopathogens. Widespread use of pesticides leads to contamination of soil and water resources, changes in the microbiome, disruption of normal plant growth and development. In order to minimize the anthropogenic impact on the territory of the agroindustrial complex and ensure the protection of cultivated plants from biotic stresses, environmentally safe analogues of chemical pesticides have been developed – biopesticides based on bacteria and fungi (have become more widespread), as well as viruses. The review, based on the analysis of 105 scientific sources, examines the advantages of these drugs, describes promising biological control agents that can be included in their composition, namely endophytic (colonize plant tissues) and extremophilic (survive in aggressive environmental conditions) microorganisms. The use of endophytic microorganisms in the fight against infectious diseases of plants is promising due to their ability to have a direct impact on the growth of crops and their induced resistance. The positive effect associated with the use of extremophilic microorganisms is associated with the universality of their use, namely the ability to maintain efficiency in various soil and climatic conditions.

The article presents the results of a three-year study (2020-2022) of 16 varieties and 17 breeding lines of spring soft wheat bred by the Federal Scientific Center for Bast Fiber Crops in the soil and climatic conditions of the Penza region. The crop productivity in the experiment varied between 1.77-4.15 t/ha. Seven samples demonstrated the highest productivity: Nastavnik, Eritrospermum 70/04-3, Irvita, Sensei, Eritrospermum 20/08-7, Lutestsens 1/12-19, Eritrospermum 15/08-4, which exceeded the standard variety Arkhat by 0.27-0.71 t/ha. During the studies the yield was related to the average variable trait (CV =11.9-19.5 %). The variation of the duration of the growing season of the studied spring wheat samples averaged 81-93 days. It was shorter in 2021 (from 67 to 80 days), the longest in 2022 (from 91 to 100 days). The height of spring soft wheat plants in the studies was a low-variable feature (CV = 3.4-8.5 %) and averaged 82.1-100.2 cm over the years. The ear grain content varied from 18 pieces in the Erythrospermum 25/08-11-18 in 2022 up to 40 pieces in the Nastavnik variety in 2021. The trait was medium-variable (CV = 11.3-18.5 %). The highest average productivity of an ear was noted in 2022 – 1.08 g, and the lowest in 2020 – 0.92 g. The high mass of grain per ear was noted in Nastavnik variety – 1.40 g, Eritrospermum 70/04-3 – 1,38 g, Irvita – 1.35 g, which were characterized by high yield. Eritrospermum 70/04-3, Eritrospermum 20/08-7 and Irvita selected by the genotype productivity were characterized by bulky grains of 40.6-43.2 g. A significant correlation was observed between the yield and the grain weight per plant (r = 0.908...0.924, P≤0.001). The studied patterns can be used in ecological breeding of soft spring wheat.

It is urgent to study the ecological and adaptive ability of oat samples in specific growing conditions to obtain high yields and resistance to biotic and abiotic stresses. In 2020-2022 in the conditions of Kirov region 47 samples of oats (standard - variety Krechet) were studied. Unfavorable conditions for the formation of yield were in 2021 (Ij = -1.2), relatively favorable – in 2020 (Ij = +0.4) and 2022 (Ij = +0.8). Yield of samples varied among the years, with the coefficient of variation varying from 2.9 % (к-14221 Рс 60, Canada) to 75.4 % (к-15536 UFRGS-11, Brazil). Twenty-four accessions, including к-15547, к-14649 (Russia), к-15464 (Kazakhstan), к-15533, к-15545, к-1554 (Brazil), к-15583, к-15585 (Sweden), etc., were responsive to improvement of growing conditions (bi>1). The amplitude of productivity changes is characterized by the stability index (Si 2 ). Stability of yield of samples к-15530 UFRGS-2, к-15541 UFRGS-17 (Brazil), к-13658 Рс 35, к-14221 Рс 60 (Canada) varied within 0.04...0.79. Samples from Canada (к-14221, к-13670), Brazil (к-15530, к-15541) and Sweden (к-15586) were the most stress tolerant. Genetic flexibility shows the reaction of plants to growing conditions, the maximum values of the trait (433 ...527 g/m2 ) were observed in samples к-15542 UFRGS-18 (Brazil), к-14648 Argamak (Russia), к-14397 Рс 67 (Canada), к-15583 Mutant 230, к-15585 Mutant 261 (Sweden). According to the results of the tests, 11 samples were selected for obtaining source material with the required parameters. The samples к-15541 UFRGS-17, к-15542 UFRGS-18, к-13662 Pc 45, к-14668 Pc 54, к-13187 Pc-56, к-14431 Pc 59, к-13658 Pc 35, к-14221 Pc 60, к-14396 Pc 64, к-14397 Pc 67 are recommended for inclusion in breeding programs. These samples are characterized by adaptability to varying growing conditions according to the "yield" trait.

The article provides the results of comparative tests on growing mini-tubers of potato in greenhouse culture using the pots with soil substrate and in the conditions of air hydroponics without hard substrates by treatment of root system with water-air nutrient mixture. The results of field testing of seed qualities of mini-tubers obtained by various methods are given. The experiments were carried out in Moscow region in potato varieties Fioletovy and Severnoe siyanie. On the basis of the research, it has been established that using the method of obtaining mini-tubers in the conditions of air hydroponics it is possible to increase the seed reproduction coefficient raising the quantitative characteristics of the yield. When growing in the conditions of air hydroponics in the Severnoe siyanie variety there was recorded two time increase of reproduction coefficient and obtained 19.2 mini-tubers per plant. At the same time, in greenhouse culture the average yield was 9.2 mini-tubers per plant. In Fioletovy variety, the reproduction coefficient in air hydroponic plants was 1.8 times higher than in greenhouse culture, 29.1 and 16.1 mini-tubers per plant, respectively. In the yield of greenhouse mini-tubers there were no seeds of small fractions, while in air hydroponic parts there were 25 % of them in Severnoe siyanie variety and 19 % in Fioletovy one. The number of fractions of large seeds more than 30 mm in size was much higher in greenhouse parts than in air hydroponic ones, 49.9 % against 1.82 % in Severnoe siyanie variety and 38.5 % against 1.3 % in Fioletovy variety. By comparative field tests of plants obtained from seed greenhouse and air hydroponic mini-tubers there has not been established significant differences in their yield and reproduction coefficient.

The genetic diversity of crop varieties should be assessed using modern molecular markers. One of the most promising and simple methods of plant genetic analysis is intermicrosatellite labeling (ISSR). The purpose of this research is to study the polymorphism of varieties of fiber flax and linseed flax included in the State Register of Breeding Achievements of the Russian Federation, as well as local forms of fiber flax using ISSR markers. The objects for the research were 83 samples from the collection of the Federal Research Center for Bast Fiber Crops, among them 24 varieties of linseed flax, 56 varieties of fiber flax of domestic and foreign breeding, and three local forms from the Central Non-Black Earth Region. Genetic analysis was carried out by PCR method using a set of 25 ISSR primers. Detection of amplification products was carried out using electrophoresis in 1.5% agarose gel. Based on intraspecific selection of flax varieties to oilseed and fiber forms, a cluster analysis was performed according to the results of ISSR labeling independently in each of two groups that allowed to increase the reliability of conclusions on the existing dependences. Dendrograms of the genetic similarity of the studied samples of linseed flax and fiber flax were studied independently from each other. As a result of the analysis, linseed flax varieties were divided into five clusters, which made it possible to establish dependencies related to their origin (originator of the variety) and oil content in the seed. The dendrogram which included varieties of fiber flax and its local forms, revealed twelve subclusters forming three uneven groups. Almost every group had its own characteristic feature, not related to the geography of origin. The grouping of varieties occurred mainly on the basis of their various characteristics in terms of flax fiber content, ripening time and resistance to environmental stress factors. The results of the research show the applicability of using the ISSR-markers as a valid and accessible method for developing the elements of marker-associative breeding of bast fiber crops.

The narrow-leafed lupine (Lupinus angustifolius L.) has long been used as a green manure crop. Alkaloid content which is incompatible with forage varieties is a desirable trait for green manure ones. Alkaloids presented in plowed biomass of the green manure lupine have disinfected action for soil resulted in the lower infection of the next crops. The undemanding nature of green manure lupine to growing conditions consists of several features: it is an active nitrogen accumulator and provides 70 % of nitrogen for own needs, and its deeply penetrated root system allows make up the deficit of nutritional substances in arable layer with use of sub-soil horizons. The aim of the study was to reveal perspective narrow-leafed lupine’s green manure varieties and breeding lines for grain and green mass yield, for length of the vegetation season, alkaloid content and other morphological and biological characters. The tests have been done under Bryansk region’s conditions (the South-West zone of the Central region of Russia) on soddy-podzolic loamy cultivated soils with the moderate fertility level. The objects of the research were seven green manure varieties and breeding lines of the narrow-leafed lupine which have been tested in competition tests of 2021-2022. The breeding line Siderat 265-19 stand out for grain (2.62 t/ha), green mass (31.9 t/ha) yield and for early maturing (84 days). Alkaloid content in its seeds made 1.003 %, the standard level. The article presents the results of structural analyses for morphological peculiarities and productivity elements of new green manure hybrid lines (the standard variety – Tshutchinskiy).). The No. 1764 (Siderat 46 x Kormovoy 344) had the best index for plant height. The No. 1749 (Siderat 46 x Bryanskiy siderat) picked out for grain productivity. The seed weight per a plant was 14.3 g and the pod’s seedingwas 5.2 seeds.

In a dry continental climate, safflower has an undeniable advantage over grains and oilseeds due to its morphological structure. The main advantage of this crop is that it is capable of extracting water from deep layers of soil with its developed root system, and due to the structural features of the vegetative mass, it can use it economically, while forming stable yields. Therefore, the search for promising varieties for the selection of new varieties, especially in the arid conditions of the Astrakhan region, continues to be relevant. Over the course of three years (2019-2021), there were studied 28 collection varieties of safflower of various ecological and geographical origin from the Federal Research Center N. I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). During the study period, 12 varieties were identified from the collection under study based on the yield and a number of economically valuable traits for further use in breeding work. The productivity of the selected samples of the studied collection varied greatly, depending on the conditions of the year and on average exceeded the standard variety Astrakhansky 747 by 0.08...0.23 t/ha. At the same time, the highest yield of the selected samples was from Tajikistan (619 Tsam-buli, 618 Shahalli-260) and Kazakhstan (620 Shirkas, 622 Center 70) – 0.43...0.51 t/ha, that was 0.15…0.23 t/ha higher than the standard. According to the oil content in the seeds (0.5...1.9 % higher than the standard) the following varieties were identified: 621 Talan (Kazakhstan) – 30.3 %, 584 Sinaloa-90 (Mexico) – 30.3 %, 619 Tsambuli (Tajikistan) – 29.4 %, 609 Akmai (Kazakhstan) – 29.1 %. The development of new varieties based on selected samples will allow to obtain stable yields in extremely arid conditions of the region.

The spread and development of sunflower rust in the regions of the Russian Federation is due to the emergence of new biotypes of the pathogen, which have overcome the resistance of cultivated varieties and hybrids. The aim of the research was to identify isolates of the sunflower rust pathogen collected in 2020-2022 in 8 regions of crop cultivation according to the internationally accepted classification: Krasnodar, Volgograd, Saratov, Voronezh, Ulyanovsk, Penza, Orenburg, and Tambov regions of the Russian Federation. Differential lines of sunflower rust resistance (CM 90, CM 29, R-386, HAR-1, HAR-2, HAR-3, HAR-4, HAR-5) and the variety VNIIMK 8833 susceptible to all races of the pathogen were used for testing. A total of 280 isolates of urediniospores of the parasite collected from infected plants of different sunflower genotypes were identified according to the internationally accepted classification. In this sample, 27 biotypes of rust pathogens were differentiated. There have been identified fifteen biotypes not previously found in Russia, their code numbers are 320, 701, 703, 710, 720, 721, 730, 742, 744, 747, 761, 765, 766, 771 and 777. The most virulent biotype 777 was detected in 2022 among isolates from the Volgograd region. The biotype with the code number 700 was detected in all the regions presented, accounting for 50 % of the sample of isolates studied. It is advisable to carry out sunflower breeding for its resistance.

Co-culturing of microorganisms can be an effective way to control their enzymatic activity and synthesis of secondary metabolites based on the phenomenon of synergism. The effect of co-culturing in different combinations of four local Streptomyces isolates on their cellulase activity, antiphytopathogenic and phytoregulatory effects was evaluated. Strains S. antimycoticus 8Al3 and Streptomyces sp. H 27-25 exhibited an antagonistic effect against fungi of the genus Fusarium and Alternaria. Binary cultures were composed so that the cellulolytic and antagonist strains were present. Significantly higher cellulase activity in comparison with monoculture (3800 units/10 min/g) was demonstrated by the binary association of strains S. griseoaurantiacus Mb 4-2 + S. antimycoticus 8Al3 (13215 units/10 min/g). When these isolates were co-cultured, an increase in the antifungal activity of the binary culture (18.76±6.1 mm) compared to that of its constituent S. antimycoticus 8Al3 (11.09±6.39 mm) was also noted. The mean value of the growth inhibition zones of phytopathogenic fungi (18.76±6.1 mm) was comparable with that of the reference preparation, the commercial antimycotic terbinafine (19.8±6.2 mm). Binary artificial associations in tests for phytoregulatory action, as well as monocultures of their constituent streptomycete isolates, had no significant effect on germination and morphometry of wheat seedlings. The absence of phytoinhibitory effect of the binary culture S. griseoaurantiacus Mb 4-2 + S. antimycoticus 8Al3, combined with agronomically valuable properties such as cellulase activity and antagonism to phytopathogenic fungi give grounds for its use for the development of a soil-improving biopreparation. Further study of the properties of the binary association, in particular, the possibility of its combination with PGPR-bacteria (Plant Growth-Promoting Rhizobacteria), will constitute the subject of further research.

The article considers the results of many years of field experiment (1968-2018) conducted in the Central part of the Non-Chernozem zone of Russia (Vladimir region). The research was carried out during eleven rotations of the four-field grain crop rotation. The study shows the effect of use of organic and mineral fertilizers applied in various doses and combinations on crop rotation yield, fertility of sod-podzolic sandy loam soil. It was found that the organomineral fertilizer system (manure 10 t/ha + N₅₀P₂₅K₆₀) provided stable crop rotation productivity (on average for eleven rotations) at the level of 39.9 c. e./ha, or 79.7 % higher than the control without fertilizers. The mineral fertilizer system at medium doses of fertilizers (N₅₀P₂₅K₆₀) was at the level of the organomineral system. The organic system was inferior in efficiency to the mineral system, both at medium doses (manure 10 t/ha) and at elevated doses (manure 20 t/ha). At the same time, the long-term use of organic fertilizers provided an increase in the humus content, depending on the dose of litter manure, by 16-36 % compared to the initial values. The use of organic fertilizers led to the stabilization of the content of available forms of potassium in the soil at an average and elevated level, respectively. Stabilization of the content of mobile phosphorus in the soil at the level of average supply was noted in mineral, organomineral and organic fertilizer systems, respectively, with low and medium doses. When using increased doses of fertilizers, there is a further increase in the content of nutrients in the soil. Growing crops in crop rotation without the use of organic and mineral fertilizers gradually led to a decrease in yield. The use of fertilizers provided greater stability of crop yields over the years of the study compared to the variant without fertilizers. The soil in the variants with organic (manure 20 t/ha) and organomineral (manure 10 t/ha + N₅₀P₂₅K₆₀) fertilizer systems was characterized by high values of the main physiological groups of microorganisms. The ratio of the number of amylolytic and proteolytic microorganisms was 1.1-1.2, that indicated a balance in the processes of mineralization of organic matter in the soil and its humification.

The article provides the results of study of protein and carbohydrate nutrition for high productive cows with milk yield of 10 thousand kg during dry period. There has been carried out the research for determining the feed protein disintegration and effectiveness of its use in cow rations. The carbohydrate nutrition for Holstein-Kholmogory cows during dry period taking into account quantity and quality of neutral detergent fiber (NDF) and acid detergent fiber (ADF) was studied. The science-economic experiment was conducted in the “Polyarnaya Zvezda”, Murmansk region in 2015 and 2021. The disintegration of feed crude protein (DP) was determined by the in sacco method, by incubation of average samples of single feeds in nylon bags in the rumen during 12 hours. Content of crude protein in feed samples before and after incubation was determined by the content of total nitrogen by the Kjeldahl method. Digestibility in the intestine of feed protein not disintegrated in rumen was determined by the mobile synthetic bag method. NDF and ADF were determined by the method of Van Soest and Southgate modified by N. N. Semina. In the experiment of protein nutrition, the content of crude protein in the ration of control and experimental groups of cows was 16 %. The content of disintegrated protein in the control group was 59.0 %, in the experimental group – 67.0 %. In the experiment of carbohydrate nutrition, in the control group crude fiber was 19.4 %, neutral detergent fiber – 38.9 %, acid detergent fiber – 23.0 % of dry matter. In the ration of experimental group of cows, the content of crude fiber was 22.4 %, neutral detergent fiber – 47.2 %, acid detergent fiber – 27.6 %. Animals of the experimental group whose ration had a crude protein disintegration of 67.0% used nitrogen more efficiently, utilized a nutritious of ration better. During the research it has been established, that the content of neutral detergent fiber of up to 47.2 % and acid detergent fiber of up to 27.6 % results in increase in digestibility of ration nutritious, improves nitrogen metabolism, intensify microbiological activity in cow rumen.

The physiological and productive effect of the developed "protected" form of choline in calves' diets after removing them from milk drinking was studied. Heifers analogs by breed, live weight at the age of three months were divided into 2 groups (n = 10), and received rations by group loose housing system. The animals of the experimental group were daily given minigranules of "protected" choline at the rate of 50 mg/ kg of live weight of the active substance mixed with feed for 90 days, with the study of the aftereffect. For 90 days of feeding the supplement, the additional increase in live weight of animals in the control group was 67.1±0.5 kg, in the experimental group – 77.5±1.2 kg, with an average daily increase in live weight of 745.5±0.01g versus 861.1±0.40 g (p ≤0.05), for 30 days of aftereffect, respectively, 733.3±0.03g versus 836.7±0.09 g. The acceleration of the growth of heifers is interconnected with the improvement of the direction of metabolic processes in their body due to the use of an additive. In the blood serum taken at the end of the experiment, there was noted a higher level of total protein – by 6.3 % (p <0.05); albumins by 8.0 % (p <0.05); creatine – by 7.4 % (p <0.05); glucose (by 21.2 %) (p <0.05); triglycerides by 28.0 % (p < 0.05); cholesterol by 10.2 % (p < 0.05); alkaline phosphatase by 7.6 %, at lower urea levels, by 22.8 % (p < 0.05), and bilirubin by 23.8 % (p < 0.05). According to hematological indicators, higher levels of erythrocyte formation were revealed – by 8.0 % (p<0.05); hemoglobin by 5.2 %; hematocrit index (by 19.5 %), with a lower (by 13.4 %) white blood cell level. A positive effect on the immune status of the organism of growing animals was also found, with a positive difference in the bactericidal activity of blood serum by 4.1 %, a higher level of lysozyme (by 50.0 %) (p≤0.05), phagocytic activity by 1.0 absolute%, phagocytic index by 14.5 %, phagocytic number by 17.5 %. The data obtained prove the relevance of giving choline in “protected” form to growing ruminants. 

With the intensive increase in the fertility traits of sows, the problem of decreasing the weight of piglets at birth has arisen. In this connection, the search for genetic variants associated with the birth weight of piglets is of particular relevance and scientific significance. The aim of the work was to identify genetic variants associated with piglet weight at birth and test them to select optimal genetic markers for selection and breeding work to improve reproductive performance of pigs on the basis of full genomic genotyping data using the Fst method. The studies were conducted in 2020-2022 on Large White pigs (n=239) bred at CJSC Plemzavod-Yubileiny in the Tyumen Region. Genotyping was performed using GeneSeek® GGP Porcine HD Genomic Profiler v1 (Illumina Inc., USA). Genomic data were filtered according to the following parameters --geno 0.1, -mind 0.1, -maf 0.05, -hwe 1e-7, --indep-pairwise 50 5 0.8. To identify genomic regions associated with piglet birth weight, there was used Fst statistics comparing genetic variants in pigs between two groups with high and low indices. Those in which the Fst values exceeded the quantile level of 0.999 were considered significant variants. Student's test was used to evaluate the significance of the effects of variant genotypes on the birth weight and number of piglets at birth. The results showed that there was a moderate negative relationship (-0.351) between piglet birth weight and number of piglets at birth. 17 SNPs associated with birth weight of piglets were identified, 9 of which were located in the KIF13A, STK24, FDFT1, ADGRD1, STX2, TMEM132D, ENSSSCG00000054866, ENSSSCG00000058459 genes, as well as SNPs rs81450496, rs80887103 in intergenic regions have been identified as promising genetic markers for increase in birth weight of piglets. The results obtained can be used to create domestic breeding technologies that improve the efficiency of pig breeding.

Using the genotyping of sheep of the Manych Merino breed on the basis of Illumina BeadChip Ovine 600K, loci suitable for genotyping by sequencing animals of this breed were found. Single nucleotide polymorphisms with a high frequency of occurrence in the range of 0.2850-0.3149 homozygotes of both wild and mutant variants were identified. Heterozygous variants of these substitutions occurred with a frequency of 0.379±0.012. The number of polymorphisms corresponding to the selected criteria was 521. Analysis of the location of the detected SNPs in the sheep genome showed their presence along the entire length of the genotyped DNA region. The largest number of polymorphisms were found on chromosomes 1, 2, 3, 17 and X. The least polymorphisms were detected on chromosomes 18, 21, 24 and 25. The resulting set of substitutions will effectively solve the problems of confirming the authenticity of the origin of sheep of the Manych Merino breed, accurately identify animals in the process of breeding work, and account for inbreeding in the population. The proposed set of SNPs is recommended both for use in genotyping by sequencing of a new generation, and for customization of SNP biochips.

Studying the antioxidant status of cow's milk can provide information both on the physiological state of the productive animal and on the resulting product in terms of its functional value, taste and characteristics affecting storage. The purpose of the work is to study milk samples from Holstein cows of the black-and-white breed with different periods of lactation (up to 30-60 days, 60-90, 90-180, more than 180 days) for the activity of antioxidant protection factors during a number of months of autumn, winter and spring periods. The total amount of water-soluble antioxidants (TAWSA) of milk was determined by the amperometric method, the activity of ceruloplasmin by the modified Ravin method, the microelement composition by the method of atomic adsorption spectrometry, the concentration of vitamin C by the titrimetric method, and the catalase number by the permanganatometry method. Patterns have been identified between the seasonal dynamics of zinc and catalase in milk: in January, in a group of animals with a lactation period of 30-300 days, catalase activity and zinc content are higher by 21.6 and 17.4 % , respectively, than in cows with a lactation period of 15-30 days; in February, on the contrary, these indicators are higher in the group of animals with a lactation period of 15-30 days (by 29.6 and 30.4 %, respectively); in March, in the group of animals with a lactation period of 15-30 days, catalase activity and zinc levels are lower (by 26.3 and 10.6 %) than in cows with a lactation period of more than 30 days. There is a decrease in TAWSA with an increase in the number of lactation days. The concentration of TCWA in the milk of cows lactating for more than 180 days decreased in November and March, by 25.9 and 13.5 %, respectively, compared with a lactation period of 30-60 days, in February – by 18.8 % compared with animals lactating 60-90 days. The obtained data on TAWSA are directly proportional to changes in vitamin C and inversely proportional to ceruloplasmin. The data obtained can serve as important guidelines in determining “reference indicators” for cows’ milk.

The market of tractors in Russia has changed greatly in recent years. A number of new suppliers have appeared on the market, abandoned brands are replaced for Russian analogues and machines from friendly countries. It is hard to evaluate all the quantitative and qualitative diversity of tractors provided to agricultural producers through the system of machine tests, especially considering that every manufacturer has a large number of standard size ranges of power equipment. Nevertheless, the customer should have access to information about the basic consumer properties and the degree of effectiveness of a particular machine unit. The article provides a computational method for evaluating one of the most important functional indicators of tractors, namely, the level of impact of its wheels on the soil, using limited initial information: technical characteristics and operational documentation of the manufacturer. The algorithm given in the text was approved during testing real tractor samples. Insignificant differences in the assessment of the maximum pressure on the soil, obtained as a result of measurements and calculations (the difference is 1.9-3.3 %) indicate a high degree of reliability of the developed methodology, as well as the possibility of its application in engineering practice to evaluate the functional indicators of tractors, including taking into account changes in their size and mass parameters when equipped with ballast weights, agricultural machines, implements, dual tires, etc. To make calculations, it is enough to know the weight of the tractor, the weight of ballast loads (mounted implements), the size of the installed tires, their static radius and the amount of tire inflation pressure. The methodology will significantly improve the quality of the predictive assessment of the level of impact on the soil of both mass-produced and designed tractor equipment.

One of the promising technologies for restoring degraded forage lands that meets the requirements of organic farming is direct strip sowing of grass seeds into the sod with mechanical cultivation of strips of soil, the width of which ensures the successful development of seedlings without the use of herbicides. To improve the quality of seeding of sod seeders, a modernized design of the coulter group has been proposed with a shoe opener mounted on a parallelogram suspension mechanism in the form of torsion springs, characterized by their vertical placement on the seeder frame (RF patent No. 2772128). To study the influence of the design and technological parameters of the coulter group based on the spring suspension mechanism on the time the mechanical system returns to the condition of dynamic balance, a laboratory installation was developed. It includes a set of measuring and recording equipment based on the multifunctional sensor WitMotion WT901WIFI MPU9250. In the process of the research, a second-order Box-Benkin experiment plan for three factors was implemented, which made it possible to determine the dependence of the damping time of oscillations of the suspension mechanism of the coulter group on the following system parameters: depth of furrow formation, length of the leashes of the suspension mechanism and mass of the shoe opener. For the selected geometrical parameters of the experimental sample of the coulter group and the established equivalent stiffness of the torsion springs, equal to 240 N‧m/rad, the range of minimum values of the transition period time is within 0.212…0.218 s and corresponds to the furrow formation depth 41.3…50.0 mm, the length of the leashes 0.13 m, the weight of the coulter 1.7...1.8 kg. The trajectory of the shoe opener during the transition process in most experiments corresponds to a damped oscillatory motion, in some cases represents an extremely aperiodic motion.

Genotypes of the 11 DNA microsatellite loci of 84 bulls of seven breeds were used to evaluate 14 indicators of allelic diversity/differentiation. Traditional and multidimensional statistical methods were applied to the data matrices from the original and transformed estimates (11×14). Estimates of heterozygosity had coefficients of variability of 8-14 %, the number of alleles per locus and indicators of differentiation of breeds at the level of 20-26 %, fixation indices – 38-44 %. Statistically significant Kendall correlations (0.8-1.0) between indicators of allelic richness and heterozygosity, fixation indices, and differentiation indicators were established. The variability of the transformed estimates of diversity/differentiation indicators by loci was in the range of 6-32 %. Including by loci Eth3, Tgla122, Eth225, Bm2113 – 6-12 %, loci Inra23, Tgla126, Eth10 – 15-20 %, loci Tgla227, Sps115, Tgla53, Bm1824 – 28-32 %. The nonparametric Mann-Whitney-Wilcoxon test showed statistically significant differences in the medians of the Eth3 locus with the Bm2113 locus, the Tgla126 locus with the Eth3, Inra23, Tgla122, Eth225, Bm2113, Bm1824, Eth10 loci. The principal component analysis (PCA) identified two components with a total information content of 95,2 %. The first one took into account 59.4 % of the total variance, had the highest loads in intra-breed diversity data and was defined as an «alpha component». The second accounted for 35.8 % of the total variance, had the highest loads in inter-breed differentiation data and was defined as a «beta component». 2D-PCA-ordination showed that a characteristic grouping of loci took place for the analyzed breeds (samples), loci and measures of diversity. Loci Tgla227 and Tgla53 formed group A, group B – loci Tgla122, Eth225, Eth10, group C – loci Inra23, Bm2113 and Bm1824. The loci of the conditional group D (Eth3, Tgla126, Sps115) were defined as «untypical». Validation of ordination was confirmed by calculations on reduced data (dimension 11×7) and the method of non-metric multidimensional scaling (nMDS). The consistency of ordinations according to the Procrust test was 96 % (pperm <0.001). A similar classification of loci was obtained by cluster analysis (UPGMA) with butstrap probabilities of cluster: A – 73, B – 100, C – 73, D – 47 %. The distances and similarity indicators (S) between the profiles of loci and the «true» summary estimates for 11 loci were calculated. Loci Tgla126 and Sps115 had S ≈ 40 %, loci Tgla53 and Bm1824 – at the level of 60 %, loci Inra23, Tgla227 and Bm2113 – 70-75 %, loci Eth3, Tgla122, Eth225 and Eth10 – 84-88 %. The average absolute deviation of the estimates of diversity indicators for the four loci with S≥84 % from the «true» estimates was 3.4 %, for the four loci with S≤60 % – 12.4 %. According to component scores, a general diversity index, γLV, was calculated for each locus. Its correlation with the estimates of the Shannon/Sherwin′s γ-diversity with a 95 % probability value was in the range of 0.73-0.98, Kendall's rank correlation was  0.67 (pvalue = 0.005). The conducted research makes a certain contribution to the expansion of tools for processing molecular genetic data in the analysis of allelic diversity in subdivided populations.