Enhancing Immune Modulation, Growth Performance and Gut Health in Broiler Chickens Through Combined <i>Pediococcus acidilactici</i> Supplementation and Influenza Vaccination

The poultry industry faces significant challenges from infectious diseases and environmental stressors, which negatively impact animal health and productivity. This study investigates the synergistic effects of Pediococcus acidilactici (PediGuard) supplementation combined with influenza vaccination on immune modulation, growth performance and gut health in broiler chickens. In a controlled trial, 300 Ross 308 broiler chicks were divided into four treatment groups: control (standard diet), probiotic-only (diet supplemented with P. acidilactici), vaccine-only (standard diet with influenza vaccination) and combined probiotic plus vaccine. The results demonstrate that P. acidilactici significantly enhances peripheral blood mononuclear cell (PBMC) viability, confirming its safety and biocompatibility. Supplementation led to marked upregulation of both pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and anti-inflammatory cytokine IL-10, indicating potent immunomodulatory effects. Combining the probiotic with influenza vaccination resulted in a substantial increase in antibody titres, surpassing those achieved by vaccination alone, thereby highlighting the synergistic enhancement of adaptive immunity. In addition, P. acidilactici significantly improved growth metrics, including weight gain, specific growth rates and feed conversion ratios (FCR), alongside significant improvements in gut morphology characterised by increased villus height and crypt depth. These findings underscore the potential of P. acidilactici as an effective, non-antibiotic probiotic strategy to improve immune function, vaccine efficacy, growth and gut health in poultry. This study supports the use of P. acidilactici as a natural approach to improving productivity and health outcomes in commercial poultry systems.