Intraperitoneal injection of β-glucan during the suckling period improved the intestinal health of newly weaned rabbits by enhancing immune responses

•Injection of β-glucan before weaning decreased the diarrhea rate in kits after weaning by training innate immunity.•Further investigation suggested that β-glucan injection before weaning enhanced the intestinal morphology in weaned kits and alleviated weaning stress.•First investigated the effect of injected β-glucan before weaning on preventing diarrhea in kits after weaning.•The intestine in the trained group maintained a better inflammation homeostasis.•The microbial communities of ileum mucus in the trained group showed a different cluster distribution. The newly weaned rabbits are susceptible to unpredictable pathogens, which often lead to diarrhea. Recent studies have confirmed that innate immunity can also be trained. An essential feature of trained immunity is a faster and stronger immune response to both homologous and heterologous reinfections. Therefore, the present study investigated the effect of intraperitoneal injection of β-glucan during the suckling period on protecting weaned rabbits from diarrhea and its mechanism. Sixty-four suckling rabbits were randomly divided into two groups based on litter and weight: the control group (C) and the trained group (T). At 6 and 4 days before weaning, rabbits in the two groups were intraperitoneally injected with physiological saline solution (PSS) and β-glucan dissolved in PSS, respectively, and 10 in each group were randomly selected two weeks after weaning for sampling. Results showed that the diarrhea rate and the crypt depth of the ileum in the trained group were decreased (P