Host-derived Limosilactobacillus reuteri R30 and Cytobacillus solani Y5 improve growth performance and intestinal health of Danzhou chickens by regulating the jejunal microbiota.

Intestinal health status is an important factor affecting of body weight (BW), and impaired growth performance is frequently associated with compromised intestinal barrier function. To address this issue, host‑derived probiotics were explored as an improvement strategy. Limosilactobacillus reuteri R30 (L. reuteri R30) and Cytobacillus solani Y5 (C. solani Y5) were isolated from the jejunal microbiota of high‑body‑weight (HBW) adult Danzhou hens. In a 42-day feeding trial, 200 one-day-old chicks were allocated to four groups: a control (CON) group receiving 1mL sterile medium by oral gavage; the treatment groups receiving the same volume of L. reuteri R30 (LR), C. solani Y5 (CS), and a 1:1 mixed bacterial suspension (LR-CS), each at 1.0 × 10⁹ CFU/mL every day. The results showed that chicks in the LR and LR‑CS groups had significantly higher BW than CON (P < 0.05). The LR group exhibited significantly increased glutathione peroxidase (GSH-Px) activity in serum, and the CS and LR-CS groups had significantly decreased levels of interleukin-6 (IL-6), IL-1β, and malondialdehyde (MDA) relative to CON (P < 0.05). Regarding intestinal morphology, significantly higher villus height (VH) and crypt depth (CD) were observed in both the ileum and jejunum of all probiotic groups. Notably, the LR group had a higher villus height‑to‑crypt depth ratio (V/C) than the CON (P < 0.05). In the LR group, both protein content and mRNA expression of Claudin‑1 in the jejunum were significantly greater, while ileal Occludin mRNA expression and protein content were increased in all probiotic groups (P < 0.05). Concerning jejunal inflammation and antioxidant status, the LR group exhibited significantly decreased IL‑6 levels, the LR‑CS group exhibited significantly reduced IL‑1β levels, and catalase (CAT) activity was significantly enhanced (P < 0.05). In all probiotic groups, the levels of MDA was decreased in the jejunum (P < 0.05). In addition, the abundance of Lactobacillus aviarius was significantly increased in the LR and LR-CS groups. In the LR group, metabolites such as β-hydroxychenodeoxycholic acid, 12-ketolithocholic acid, and hyocholic acid were positively correlated with the Clostridia and Clostridiaceae. Notably, these metabolites were significantly positively correlated with BW and serum GSH-Px activity, and significantly negatively correlated with serum IL-6 levels. These findings suggest that L. reuteri R30 and C. solani Y5 can promote growth and improve intestinal health, and these benefits were associated with alterations in the gut microbiota and host metabolism.