Olga Nikolaevna Polozyuk’s research while affiliated with Orel State Agrarian University and other places

The authors found out that throughout the experiment, the dynamics of the live weight of broiler ducks of the Agidel 345 cross was greater in the second experimental group, which received the probiotic “Subtilis”. At the end of the experiment, the body weight in this group was 3822.5 g, which is 3.8% (144 g) and 2.6% (99.1 g) more compared to the control and first experimental groups.The use of probiotics “Prolaxim-В” and “Subtilis” also had a positive effect on meat productivity indicators. In the first experimental group, where Prolaxim-B was used as a probiotic, and the second experimental group, where the probiotic Subtilis was used, the yield of muscle tissue was higher than in the control group by 0.6 and 1.2%. In the first experimental group, the yield of internal fat was greater than in the control group by 2.6 g, but less than in the second experimental group by 4.9 g.

The authors conducted experiments to study the effect of natural metabolites fed to repair pigs in the last three months before insemination on their growth, changes in their live weight, the chemical composition of milk and the content of immunoglobulins in it, as well as morphological and biochemical blood compositions, protein, carbohydrate and lipid metabolism in pregnant and suckling sows. Four groups of repair pigs were formed for research white breed (control and three experimental) at the age of 6 months, 20 heads each, which were kept in separate machines. The control group received the basic diet, without additives. The pigs of the experimental groups were fed natural metabolites from the sixth to the ninth month inclusive. The animals of the I experimental group were fed organic selenium (Selenium) as part of the compound feed – 0.3 kg / t of feed, II experimental group – succinic acid at the rate of 20 mg / kg of live weight (frequency of 10 days), III experimental group - Carolin preparation (beta-carotene oil solution) – 15 ml / head per day. At the ages of 6.5 and 9 months, 5 pigs from each group had blood taken from the ear vein in the morning before feeding for research. The object of research was repair pigs of large white breed and Krasnodar meat type. Feeding of animals both in this experiment and subsequent ones was carried out taking into account detailed feeding standards. The composition and nutritional value of the diets were calculated using the «Kormoptimaexpert» program.

The presented studies were conducted in the period from 2021 to 2023 in the conditions of the center "Safety and Effectiveness of feed and additives" of the Volgograd State Agrarian University on the ROSS-308 bird. To perform the study, four groups were formed in three repetitions: control, I-experienced, II-experienced and III-experienced with 40 heads each. The bird was raised from the daily to 37-day age with outdoor maintenance. The chickens were kept on a deep litter (sawdust), the feeding technology, watering and microclimate parameters meet the requirements of the ROSS-308 cross. The chemical composition of fish concentrate exceeds fishmeal in terms of crude protein content by 2.15%, crude fat – by 0.25%, crude ash – by 0.28%, which suggested the replacement of fishmeal in broiler chicken feeding programs for this feed product. The use of Volgafish fish concentrate in the composition of compound feeds for broiler chickens, replacing 50.00%, 75.00% and 100.00% fishmeal, allowed to increase the average daily growth of poultry by 1.38-5.18%, and the live weight of individuals by 37 days of age by 1.32-5.01%.

The authors carried out a study of the biochemical parameters of the blood of ducklings and found out that the use of the probiotic "Subtilis" throughout the experiment provides an increase in the content of calcium and phosphorus in the experimental group of ducklings by 13.1 and 16.3% compared to the control group, which positively influenced on the development of the musculoskeletal system. Herewith, the calcium-phosphorus ratio of ducklings at 55 days of age was higher 0.22% in favor of the experimental group. Also, the use of the probiotic "Subtilis" had a positive effect on the total protein index, which was higher by 2.1 g/l in the experimental group compared to the analogs of the control group at the end of the experiment. The uric acid indicator was within the reference values, which indicates that this probiotic did not have a toxic effect on the body.

The article presents the results of studies of the histological structure of the muscle tissue of the longest back muscle of purebred piglets of the KB and L breeds of different genotypes. Recommendations are given for carrying out DNA genotyping of livestock in the early postnatal period on pig breeding complexes and farms, in order to leave young animals with the desired genotype for the tribe on complexes with a completed production cycle. According to the results obtained, it is recommended to use animals with the NN genotype of the RYR-1 gene in feedlots to increase quantitative and qualitative indicators of meat productivity.

The results of the influence of the biologically active substance “Amylocin” on nonspecific factors of protection of the organism of sows in the second half of gestation and in the first decade after farrowing are presented. It was found that the cellular indications of the natural resistance of the organism throughout the experiment were higher in the experimental group of the lactating sows, that received the biologically active substance, in comparison with the gestating and lactating sows of the control group. Humoral indications of natural resistance of the organism: lysozyme activity of blood serum was higher in the experimental group of the lactating sows in comparison with gestating and lactating sows of the control group by 12.5 and 5.2%; On the contrary, bactericidal activity of blood serum was higher in group of sows during the second half of gestation by 18.9 and 24.9% than in the experimental and control groups of farrowing sows. There were no postpartum complications in the experimental group of sows, the safety of the obtained young growth was higher by 8.6% in comparison with the control group.

The authors proposed the use of the probiotic "Subtilis" to the ducklings of the experimental group, which allowed them to have a greater increase in body weight throughout the experiment compared to the analogues of the control group. The greatest increase in body weight was observed when weighing a poultry at the age of 36,44,50 days and during these periods it was on average higher by 106.5 g in the experimental groupcompared to the control group. Over the entire period of growing, the dynamics of the body weight of the experimental group of ducklings was higher by 3.7 % from the analogues of the control group. The average daily body weight gain of ducks was 6.1 g (9.2%) more in the period from 16 to 22 days of growing in the experimental group than in the control group. The preservation of the experimental poultry population in the period from 1 to 50 days of life increased by 7%, the growing time was reduced by 4 days.

The impact of gene mutations in the RYR-1 gene on the physicochemical qualities and nutritional value of homozygous and heterozygous stress-resistant NOR carcasses with RSE and DFD defects was studied using molecular genetics methods. NOR, which is meat of homozygous cross-breeding pigs, had a 0.44 higher pH level, 2.62% higher water-holding ability, 2.36 units×103 higher color and 0.37% higher content of organic matter; the tryptophan content and protein-quality index were lower by 0.3 mmol/g and 0.29, respectively. This low acidity caused the denaturation of some sarcoplasmic proteins, which contributed to the loss of the meat’s water-holding ability. A sharp decrease in pH led to partial denaturation of the sarcoplasmic proteins, which determined the pale color of the PSE meat. It was found that, compared to the heterozygous stress-sensitive animals with DFD defects, the NOR pH level was 0.55 lower, the water-holding ability was 4.05% lower, and the color intensity was 4.97 units×103 lower; the protein-quality indicator amounted to 8.24, which was 1.12 higher than that in the heterozygous stress-sensitive animals with DFD defects. The defects had a significant impact on other physicochemical properties of the meat. Defects of PSE meat worsened meat color. The intensity of staining of muscle tissue with PSE defects was lower than in normal pork by 11.5, 8.7 and 6.4 units×103 , respectively. DFD-pork exceeded normal meat in color by 13.7 (P> 0.99), 9.5 (P> 0.99) and 7.4 units×103 . Keywords: stress tolerance, stress sensitivity, genotype, meat defects PSE and DFD-, RYR-1 gene, pH, water-holding ability, meat coloring

It was found that the use of a prebiotic based on blue-green microalgae in pigs in the early postnatal period of development improved their reproductive qualities. The weight of the nest at birth and the live weight of piglets at weaning in the first litter gilts of the control group was 9.5 and 23.7% less than in the sows of the experimental group. The milk production of the ewes in the experimental group was 8.4 kg higher than in the control group. As they grew and were able to use additional feeding, the piglets in the experimental group overtook their peers and by weaning had a live weight of 14.3 kg (23.7%) more than in the control group. The safety of piglets obtained from the first litter gilts of the experimental group during the weaning period (32 days) was 5.3% more than the control.