Early gut microbiota transplantation in broiler chicks exerts effects on intestinal health depending on the donor’s microbial composition

Fecal microbiota transplantation (FMT) is a promising strategy for modulating the gut microbiota to enhance broilers' health. This study investigated the effects of FMT of broilers (FMT1), laying hens (FMT2), and broiler breeders (FMT3) as donor on the intestinal health of chicks as recipients. A total of 144 newly hatched Ross 308 male broilers were randomly assigned to four groups and reared until D 14. For the first three days after hatching, the control group received 1 mL of saline daily via oral gavage, while the FMT groups received their respective inocula. Body weight, intestinal length, and ileal histomorphology were assessed on D 5, D 7, and D 14. In addition, on D 7 and D 14, ileal tissues and serum were collected. The expression of critical genes related to barrier function, nutrient transport, mitochondrial function, antioxidant defense, signal transduction, innate immunity, cytokine response, and programmed cell death were measured using high-throughput qPCR. Furthermore, serum metabolites related to tryptophan metabolism were also determined. Group differences were analyzed using one-way ANOVA with Tukey's post-hoc test. Partial Least Squares Regression (PLSR) model was used to evaluate the interaction between observed changes and dominant microbiota. No significant effects on body weight or intestinal length were observed. On D 7, FMT1 induced innate immune stress, characterized by upregulated Toll-like receptor signaling, apoptosis, and mitochondrial biogenesis. In contrast, FMT2 and FMT3 improved intestinal histomorphology. Notably, FMT2 enhanced antioxidant defenses and changed tryptophan metabolism, while reducing reliance on glucose transporters. Meanwhile, FMT3 suppressed pyroptosis and enhanced barrier integrity. PLSR analysis identified 9 features that contribute over 30% of observed variations, with Olsenella, Blautia, and unclassified Lachnospiraceae being the most pronounced. By D 14, most effects had diminished, although antioxidant effects in FMT1 and immune markers in FMT2 and FMT3 persisted. Overall, FMT exerted donor-dependent patterns of influence on intestinal health, and our study proved programming of gut physiology through fecal microbiota transplantation.