The Effects of Injection of Synbiotics on the Early Growth Performance and Intestinal Health of Chicks.

In this study, the effects of synbiotic inclusion at the intra-amniotic stage in layer chicks were evaluated with different parameters, such as performance, immunological function, intestinal development, and cecal microflora content. A total of 1,200 eggs with fertile embryos were allocated into four treatment groups. For every treatment, five replicates were used, and 60 eggs were included in each replicate. The following four treatment groups were established: the non-injected group, 0.9% physiological saline injection (saline) group, 1 × 10 CFU/egg injection (probiotic) group, and 1 × 10 CFU/egg + 2 mg/egg Astragalus polysaccharide injection (synbiotic) group. injection was carried out at 18.5 days of incubation. The results showed that injection of probiotics or synbiotics did not affect the hatching or growth performance of the chicks but significantly increased their feed intake (FI), body weight (BW), and the feed conversion ratio (FCR). Additionally, injection of synbiotics enhanced the levels of serum interleukin-2 (IL-2), interferon-γ (IFN-γ), and secretory immunoglobulin A (SIgA) in intestinal lavage fluid and the histomorphological development of the small intestine. Our results also indicated that intra-amniotic synbiotic injection significantly increased and colonization while decreasing the relative abundance of in the chicken cecum ( < 0.05). In summary, injection of synbiotics had positive impacts on the performance, immunological function, gut development, and microbiota of growing chicks.