Concentration of some hormones and quality of boar semen after feeding liposomal vitamin complex with zinc gluconate under heat stress conditions

The aim of the work was to determine the effect of feeding a liposomal vitamin complex with zinc gluconate under heat stress (HS) on the concentration of individual hormones and the quality of boar sperm. The experiment was conducted on nine clinically healthy breeding boars, aged 2–4 years of Landrace, Pietren and Duroc breeds. Three stages of the study were conducted, each lasting 30 days, in which the selection of material and its analysis were similar: 1) under normal thermal conditions (<23°C); 2) under HS conditions (25–30°C); 3) under feeding a complex liposomal supplement under HS conditions (25–30°C). In the third stage of the research on the background of HS, all boars were individually given a feed additive in the form of a liposomal emulsion for 30 days, which included vitamins A, D3, E, and C with zinc gluconate in a dose of 2 ml. At the end of each stage of the experiment, blood samples were taken from the experimental boars. The concentration of testosterone, cortisol, and thyroxine in blood plasma was determined by the enzyme-linked immunoenzymatic assay method. After completing each stage, ejaculates were taken from the boars by manual method twice a week for two weeks. The parameters of motility and morphology of germ cells, the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were determined. It was found that under the influence of HS in the blood plasma of boars, the level of cortisol (P<0.01) and thyroxine (P<0.05) increased, while the concentration of testosterone significantly decreased (P<0.05). The negative effect of HS on spermatogenesis is confirmed by a significant (P<0.001) decrease in the concentration of testosterone in the plasma of sperm. Moderate HS reduces the overall motility of sperm of breeding boars (P<0.001) and the activity of germ cells with rectilinear translational movement (progressive motility; P<0.01), and doubles the percentage of degenerated sperm (P<0.001). Under the influence of HS, a decrease in the activity of GPx and CAT (P<0.001) is observed in the sperm of boars against the background of a slight increase in the activity of SOD. After feeding the liposomal supplement under the action of HC, the concentration of cortisol and thyroxine in the blood of boars significantly (P<0.05–0.01) decreased, the level of testosterone in the blood and semen of boars significantly increased (P<0.05–0.001). This led to an improvement in sperm motility and their morphological characteristics: the total sperm motility significantly increased (P<0.01) and the activity of sperm with progressive motility (P<0.01) with a simultaneous decrease in the percentage of degenerated sperm (P<0.01). At the same time, the activity of SOD significantly decreased (P<0.01) with a simultaneous increase in the activity of GPx (P<0.001) and CAT (P<0.001).