Influence of plant-based antioxidant and immune-enhancing agents on blood profiles, growth metrics, carcass traits, and gut microbiota in broiler chickens

This study evaluated the effects of licorice extract (LE) and echinacea extract (EE) supplementation in drinking water on growth performance, water utilization, carcass traits, serum biochemistry, antioxidant status, immune response, and cecal microbiota in broiler chickens. A total of 350 Cobb 500 chicks (7 days old; 184 ± 1.28 g) were randomly assigned to five treatments with seven replicates of 10 birds each. The treatments included a control group (drinking water without additives), LE at 1.0 mL/L (LE1) and 2.0 mL/L (LE2), and EE at 1.0 mL/L (EE1) and 2.0 mL/L (EE2). The supplements were provided via drinking water from day 7 to day 35. Growth performance parameters such as live body weight, daily weight gain, feed intake, feed conversion ratio (FCR), and performance index (PI) were not significantly affected (P > 0.05). In contrast, water consumption and the water-to-feed ratio were significantly reduced (P < 0.05), with the greatest reduction observed in the EE1 group. Carcass characteristics responded differently to the two extracts: LE1 significantly increased carcass yield, dressing percentage, and spleen weight, whereas EE2 markedly reduced abdominal fat deposition (P < 0.01). Both extracts improved serum lipid metabolism, evidenced by lower total cholesterol, triglycerides, low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) concentrations and higher high-density lipoprotein (HDL) levels (P < 0.01). Immune and antioxidant responses were also enhanced, as indicated by increased IgM and IgY concentrations, elevated superoxide dismutase (SOD) activity, and reduced malondialdehyde (MDA) levels, with the most pronounced effects observed in LE1 (P < 0.001). Cecal microbiota analysis revealed a reduction in coliforms and Escherichia coli counts, while lactic acid bacteria populations remained unaffected. In conclusion, although LE and EE supplementation did not influence growth performance, they improved water-use efficiency, carcass quality, lipid metabolism, antioxidant capacity, immune status, and gut microbial balance. Among the tested treatments, LE1 and EE2 exerted the most beneficial physiological effects, indicating their potential as functional drinking-water additives in broiler production.