Cecal microbiota transplantation enhances calcium retention through modulation of gut microbiota and intestinal calcium transporter gene expression in chicks.

Bone development during early life is crucial for maintaining skeletal health and productivity in laying hens. The aim of this study was to investigate the effects of transferring cecal bacterial material of healthy adult hens on growth performance, gut integrity, microbial development, and bone metabolism of recipient chicks. Cecal contents were collected from 12 healthy Lohmann Pink-shell laying hens aged 47 weeks (donors). A total of 120 1-day-old Lohmann Pink chicks (recipients) were randomly assigned to 2 treatments for a 34-day trial: CONT (0.1 mL saline, Control) and CMT (0.1 mL cecal microbial solution). Each group had 10 replicates and 6 chicks per replicate. The pooled cecal sample as well as saline was administered via oral gavage once daily from day 1 to day 10, and then boosted on days 16, 23, and 30. One bird from each replicate was randomly taken for sample collection at day 34 (n=10). The results showed that CMT chicks had significantly higher Ca and P retention rates than CONT chicks. The mRNA expressions of intestinal Ca transporters, CaBP-D28K and VDR in the ileum and NCX1 in the jejunum, were also upregulated in CMT chicks. Additionally, the mRNA expression of a tight junction protein, ZO-1, was upregulated in the duodenum of CMT chicks. CMT chicks also had higher mRNA expressions of pro-inflammatory cytokines, IL-6, IL-1β, and TNF-α, in the intestinal tract. Furthermore, CMT chicks had a more diverse and mature gut microbial community compared to CONT chicks. The relative abundances of SCFA-produced bacteria (e.g., Bacteroides, Rikenellaceae_RC9_gut_group, and Prevotellaceae_UCG-001) were increased, while the relative abundances of Alistipes, Lactobacillus, and Barnesiella were reduced in CMT chicks. However, there were no CMT effects on body weight, organ indexes, bone morphology, and gene expression-associated with bone metabolism. This study demonstrates that transferring cecal bacteria from adult laying hens enhances calcium absorption and retention in newly hatched chicks by upregulating key calcium transporters and enhancing intestinal barrier integrity via modulating the gut microbiome.