Abstract
Inactivated probiotics have gained attention for their positive health impacts, notably enhanced safety, stability, and tolerance, yet their mechanisms remain unclear. In this study, we evaluated the effects of dietary supplementation with inactivated Lactiplantibacillus plantarum Ps-8 (ILPs-8) on the intestinal health and growth performance of broiler chickens. A total of 220 one-day-old male 817 broiler chickens (initial weight: 20.97 ± 3.10 g) were randomly allocated into two groups: a control (Con) group receiving a basal diet and an ILPs-8 group receiving a basal diet supplemented with ILPs-8 at a concentration of 500 mg/kg. Supplementation with ILPs-8 significantly improved the growth performance of broiler chickens, especially the average daily gain and feed conversion ratio during the early growth phase (days 1-21) (P < 0.05). Furthermore, ILPs-8 markedly enhanced the activities of digestive enzymes and improved the villus morphology in the small intestine (P < 0.05). Serum IgG and intestinal sIgA levels were higher in the ILPs-8 group compared to the Con group (P < 0.05). Moreover, significant differences in gut microbial composition and functional profiles were observed between the two groups. Interestingly, ILPs-8 supplementation notably increased serum metabolite levels associated with energy metabolism, immune modulation, and anti-inflammatory responses (e.g. l-Glutamine, 2-Hydroxycinnamic acid, 2-Ketobutyric acid, and Spermine). Correlation analyses further indicated potential linkages between growth and immune performance, altered gut microbiota, and serum metabolite levels. Our findings demonstrate that dietary supplementation with ILPs-8 significantly enhanced broiler chicken growth performance and intestinal health. The beneficial effects of ILPs-8 appear to be mediated by modulation of immune responses, gut microbiota composition, and serum metabolite profiles.