Plant-based feed additives, also known as phytobiotics, show great promise to compensate deficiencies of important biologically active substances in the diet. Therefore, this study aimed to evaluate the effect of Germivit on the feed supplement of cattle of different ages. In the first experiment, four groups of 9-month-old Simmental calves (10 animals in each group) were fed with Germivit at 0.0, 0.5, 0.7, and 0.9 g kg-1 live body weight, respectively. In the second experiment, three groups of pregnant cows (10 animals in each group) received Germivit at 0.0, 0.25, and 0.50 kg-1 live body weight, respectively. The morphological composition of the collected blood was studied using a PCE-90vet automatic hematology analyzer. The blood biochemical composition was studied using a Stat Fax 1904 biochemical analyzer, and the immunological status of the animals was evaluated using generally accepted methods in veterinary medicine: immunocompetent cells by spontaneous rosette formation; immunoglobulins by the radial  immunodiffusion method; phagocytosis by using S. aureus culture; serum lysozyme activity by the photoelectrocolorimetric method; and bactericidal activity of serum by determining the degree of growth inhibition of the mixture of daily  culture of E. coli in a nutritive culture broth. Germivit contributed to the improvement of the biochemical and immunological parameters in the calves. In the cows, an increase in the morphological parameters of blood was observed, their immune status improved, and their calves were born with high rates of natural resistance and health. Germivit had a positive effect on the functional state of cattle.