The dissertation is devoted to studying the effects of magnesium citrate and the probiotic Lactobacillus casei B-7280 on mineral nutrition, protein metabolism, reproductive function of honey bee queens, and the viability of their brood. Modern physiological and biochemical research methods were applied to trace the characteristics of the microbiota in the midgut and hindgut of bees, as well as the functional activity of the queens’ reproductive system after spring feeding with magnesium citrate and the probiotic.
The research was carried out at the apiary of the Laboratory of Environmental Physiology and Product Quality of the Institute of Animal Biology of NAAS. The first phase of experiments was conducted under conditions of isolated maintenance of bees in a thermostat with feeding sugar syrup supplemented with different concentrations of magnesium citrate. Daily monitoring of bee mortality, mobility, and feeding activity was performed. The second phase was conducted in stationary conditions at the apiary, where two groups of bee colonies, similar in strength, queen age, and biomass, were formed. The control group received sugar syrup, while the experimental group received syrup supplemented with nanotechnological magnesium citrate.
The second stage of research involved probiotic strains Lactobacillus casei B-7280 and Lactobacillus plantarum B-7679. Three groups of bee families were formed: the control group fed only sugar syrup, and two experimental groups with different concentrations of probiotics. Before the experiments, the viability of lyophilized probiotic strains was tested on MRS agar at 37 °C.
For the first time, a scheme for supplementing sugar syrup with magnesium citrate during spring feeding was developed. It was demonstrated that this supplement activates mineral metabolism, improves the quality of bee products, and enhances queen egg-laying intensity. Both synergistic and antagonistic effects on mineral levels in tissues were observed: high doses of magnesium citrate reduced Fe, Zn, Cu, and Mn, while low doses had no significant effect except for an increase in Mn.
Magnesium citrate also influenced the protein profile of bee hemolymph: albumins and β-globulins decreased, whereas α2- and γ-globulins increased. Elevated catalase activity and glycogen content indicated improved carbohydrate energy supply. In summer–autumn, feeding magnesium citrate increased the reproductive activity of queens and changed mineral content in bee tissues and honey, with lower Fe, Cu, and Zn levels but higher diastase activity and proline content.
The probiotic L. casei B-7280 proved effective in enhancing bee viability, resistance, and gut microbiota balance. Its use, along with L. plantarum B-7679, led to an increase in lactic acid bacteria and bifidobacteria and a decrease in undesirable microbes. The optimal concentration of L. casei B-7280 was 10⁶ CFU/mL, which significantly improved survival rates and microbiological balance.
The scientific novelty lies in the first substantiated evidence of the physiological and biochemical impact of magnesium citrate on bees and determination of optimal supplementation doses. Differences in the effects of L. casei and L. plantarum on protein and mineral metabolism were also established. The practical value of the results is in developing scientifically grounded recommendations for using magnesium citrate and probiotics in spring feeding to enhance bee viability, productivity, and reproductive performance.
The findings have been implemented in the activities of research institutions and are used in teaching courses such as “Animal Physiology” and “Beekeeping” at higher educational institutions of Ukraine.
