Effects of supplementation with a novel strain of <i>Paenibacillus konkukensis</i> on laying performance, tibial characteristics, and caecal microbiota in laying hens

Paenibacillus konkukensis SK 3146, a novel strain with diverse enzyme genes, is a potential probiotic; however, its effects on egg productivity and gut microbiota in laying hens remain unexplored. This study aimed to evaluate the in vitro probiotic characteristics of P. konkukensis and its effects on laying performance and physiological traits in laying hens. The enzyme and antimicrobial activity of P. konkukensis was investigated in vitro. A total of 216 70-week-old Hy-Line Brown hens were assigned to four groups: basal diet without feed additives (control); basal diet + 0.1% P. konkukensis (PK0.1%); PK0.3%; and PK0.5%. Paenibacillus konkukensis produced digestive enzymes, including lipase, xylanase, and amylase. The PK0.5% tended to have the longest bones (linear, p = 0.07) and the PK0.3% tended to have the highest bone mineral density (quadratic, p = 0.08). The PK0.3% showed significantly greater villus height in the jejunum than the control and PK0.1% (linear, p < 0.01), while the PK0.5% showed higher villus height in the ileum compared to the control (linear, p < 0.05). The villus-to-crypt ratio was significantly higher in the PK0.1% and PK0.3% than in the control (quadratic, p < 0.05). The PK0.3% and PK0.5% showed notable alterations in the gut microbiota composition in principal coordinate analysis. The relative abundance of lactic acid bacteria was higher in the PK groups (linear, p < 0.01). This study indicates that PK treatment can improve bone health, intestinal morphology and modulate the gut microbiota, highlighting its potential as a probiotic for laying hens.