The dissertation is devoted to the study of biochemical indicators of rabbit blood after weaning under conditions of varying levels of heat stress and the use of Zn, Ge, and Se nanocitrates to mitigate its negative effects.
The first chapter, «Literature Review», provides a thorough analysis of domestic and foreign scientific literature in the field of research, in particular, it reveals the biological characteristics of rabbits and the impact of heat stress on their changes, and shows the physiological significance of zinc, selenium, and germanium in rabbit nutrition, and the application of nanotechnology methods in animal husbandry.
The second chapter, «Conditions, Materials, and Research Methods», reveals the specifics of conducting experiments, describes the physical characteristics of Zn, Ge, and Se nanoparticles, the scheme and basic research methods used to accomplish the tasks set in the dissertation.
The third section, «Results of our own research», analyzes the effect of Zn, Ge, and Se citrate nanoparticles on morphological and biochemical blood parameters under normal conditions and under moderate (27.8–28.9 °C) and severe (28.9–30 °C) heat stress.
The use of zinc (12 mg/kg body weight), selenium (60 μg/kg body weight), and germanium (12.5 μg/kg body weight) citrate nanoparticles in the diet of rabbits after weaning had a positive effect on the oxygen transport function of blood under conditions of moderate and severe heat stress, with an increase in the number of erythrocytes (p<0.05–0.01), hemoglobin content (p<0.05–0.001), hematocrit (p<0.05 – 0.01) and a decrease in the number of leukocytes (p<0.05) on days 14 and 29 of the experiment, which was more pronounced in animals that were given zinc and selenium citrate.
Feeding rabbits with nano-compounds of microelements leads to the strengthening of the body's adaptive processes under conditions of moderate and severe heat stress. In particular, under the influence of zinc citrate in the blood, a lower creatinine content (7.3 and 7.5 %), a decrease in AST activity (16.9 and
35.0 %), ALT (12.4 and 23.5 %), and lower cholesterol (22.2 and 27.3 %). Selenium citrate contributed to a decrease in creatinine levels (7.3 and 7.5 %), a decrease in ACT activity (13.0 and 15.2 %) and ALT activity (10.5 and 18.5 %), lower cholesterol levels (16.6 and 17.8 %) and urea levels (19.9 and 17.7 %), germanium citrate resulted in a decrease in urea content (19.9 and 20.3 %) on days 14 and 29 of the experiment.
Under conditions of moderate heat stress, the administration of micronutrient nanoparticles had a pronounced antioxidant effect on the rabbits' bodies, in particular: zinc citrate, lower levels of LHP (p<0.001) and TBA-active products (p<0.001) were observed on day 14 of the study, and higher superoxide dismutase activity (p<0.01) was observed on day 29; zinc and selenium citrates caused an increase in catalase activity (p<0.01; p<0.05) and GSH content (p<0.01; p<0.001) on days 14 and 29 of the study.
The use of zinc and selenium citrate nanoparticles under conditions of severe heat stress contributed to the activation of the antioxidant defense system, which led to a decrease in the intensity of lipid peroxidation processes and an increase in the activity of key antioxidant enzymes, in particular a decrease in LHP content (p<0.001) on days 14 and 29, an increase in superoxide dismutase (p<0.01) and catalase (p<0.05) activity on day 29. At the same time, an increase in the content of GSH (p<0.001) on days 14 and 29 and an increase in glutathione peroxidase activity (p<0.01) were recorded after drinking selenium citrate on days 14 and 29 of the experiment.
The use of zinc, selenium, and germanium citrate nanoparticles under conditions of moderate and severe heat stress significantly modifies lipid metabolism in rabbit blood, but the nature and severity of the changes depended on the element and the intensity of the stress factor. Zinc citrate reduced cholesterol levels (21.1 and 13.5 %) and increased phospholipid content (16.9 and 8.3 %) on days 14 and 29 of the study, respectively. Selenium citrate has a pronounced hypocholesterolemic effect with a simultaneous increase in phospholipid content (23.3 and 26.3 %) on days 14 and 29 of the experiment. Germanium citrate reduced cholesterol content (8.4 and 23.4 %) and increased phospholipid content (14.2 and 10.7 %) on days 14 and 29 of the study.
Feeding rabbits zinc citrate for 29 days resulted in higher levels of Zn in liver, kidney, and wool tissues by 27.9, 26.7, and 26.4 %, respectively, Se in the liver by 24.0 %, Ge in wool by 35.6 %, Mn in muscles by 43.1 %, Cu in the liver by 45.2 %, and Co in wool by 24.3 %. Changes in the content of these trace elements were more pronounced in the studied tissues of rabbits when nano-compounds of selenium and germanium citrat
