Influence of black garlic and Hypericum scabrum on growth performance, fecal microbiota, diarrhea, oxidative stress and immune status in pre-weaning calves.

This study investigated the effects of supplementing milk with fermented black garlic (G) and Hypericum scabrum decoction (H) on growth performance, immune status, diarrhea incidence, inflammatory responses, oxidative stress, and gut microbiota in 28 pre-weaning Holstein calves. Blood WBC counts were significantly higher in the control (C) group than in the treatment groups (P = 0.007). At 45 days of age, CAT activity was significantly higher in the C group as compared to experimental calves. Concentration of IL-6 was significantly lower in the treatment groups (P < 0.01). Regarding gut health, fecal scores significantly improved in supplemented groups, particularly on day 45 (P < 0.05), and fecal E. coli counts were reduced by 10.7% in the GH group (P = 0.043). Serum IgA was significantly higher in the GH group (P = 0.044), suggesting a more robust first-line immune defense. However, a selective antimicrobial effect was observed, as bifidobactera levels also decreased by 9.8% and 8.7% in G and in GH groups as compared to C (P = 0.024). No significant differences were observed between groups in live weight and body measurements throughout the experimental period, except for in heart girth on day 60 (P < 0.05). Starter consumption did not differ between groups, furthermore, the C group had higher FCR and group H had higher ADG than the C group during the 0-60-day period, and no difference was observed in FCR and ADG during other periods In conclusion, while fermented black garlic and H. scabrum support gastrointestinal health and modulate inflammatory responses, their impact on overall growth performance remains limited under the studied conditions, and the reduction in beneficial bifidobacterium warrants careful long-term evaluation.