Serine protease-loaded inulin microsphere with Bacillus subtilis qb1-based synbiotic for improved growth indices in Ross 308 broilers

The use of antibiotics in poultry has raised concerns about antibiotic resistance, increasing interest in alternative approaches to enhance broiler performance. The current study evaluated the effects of combining serine protease (SP) loaded inulin microspheres with Bacillus subtilis (QB1) on the growth indices, health indicators and meat quality of Ross 308 broilers. A total of 105 chicks were equally divided into six treatment groups and one control group: control (S1), 0.5 g/kg Bacitracin (S2), QB1 at 106 CFU/g (S3), 1g/kg inulin (S4), 10 mg/kg SP (S5), synbiotics (1 g/kg inulin + QB1 at 106 CFU/g) (S6) and SP loaded inulin microspheres (10 mg/kg) + QB1 at 106 CFU/g (S7). S7 significantly outperformed others, with body weight gain of 1907 g, feed intake of 3182 g, feed conversion ratio of 1.554, energy efficiency ratio of 23.23 and protein efficiency ratio of 3.417 (P<0.05). S7 improved breast (6.42) and thigh (6.50) pH, water holding capacity (80.27% breast and 76.17% thigh), protein (26.60% breast and 24.71% thigh), extract release volume (33.36 thigh and 32.63 breast) (P<0.05). These results suggest that SP loaded inulin microspheres combined with QB1 offer a promising antibiotic alternative, enhancing growth indices, meat quality, and health in broilers.