Comparison of the impact of yeast products, herbs, and dried chokeberry on growth performance, antioxidant and immune status, feeding activity, and residual effects in young fattening bulls

This study aimed to investigate the effects of yeast-based, and phytogenic additives on immunity, activity, and production performance in young fattening bulls. The experiment involved ninety-six Limousine bulls (weight 400±30 kg), divided into eight groups (12 animals each). It lasted 160 days and was divided into two phases. In the first phase (days 1–80), animals received standard diet with dietary additives: control (CON - no additive), symbiotic yeast (Y1 -5 g/kg DM TMR), selenium-enriched yeast (Y2 - 3.5 g/kg DM TMR), dried chokeberry pomace (CB1 – 13 g/kg DM TMR, CB2 – 22 g/kg DM TMR), herbal mixtures (H1 - 9 g/kg DM TMR, H2 - 13 g/kg DM TMR), and a combination of chokeberry pomace and herbs (CBH-13 g + 9 g/kg DM TMR). The herbal mixture contained marshmallow leaves, lovage root, thyme, and garlic. In the second phase (days 81–160), all animals were fed only standard diet to assess the residual effects of the additives. Animal activity was continuously monitored during the experiment. Weight measurements and blood samples were taken at 40, 80, and 160 days to assess antioxidant potential, immunoglobulin levels and biochemical markers. H2 showed the highest daily weight gain for both stages, while the CON had the lowest (p≤0.01). At the end of the experiment, total antioxidant capacity (TAC) was higher in H1, while IgG increased in Y2, CB1, H1, and CBH groups compare to CON. IgM and IgA were higher in H1 and H2 (p≤0.01). Futhermore, animals in CB2 and H1 groups spent less time feeding and ruminating but were more inactive. In conclusion, the study demonstrated that natural additives can positively influenced growth, health indicators, antioxidant potential, and animal behavior, even 80 days after their withdrawal.