Effects of in ovo feeding of small peptide chelated zinc on antioxidant capacity and inflammatory response of the intestinal tract in chicks

This study aimed to investigate the effects of in ovo feeding (IOF) of small peptide chelated zinc (SPCZ) on zinc content, antioxidant capacity, and the expression of genes related to apoptosis and inflammation in the intestinal tract of chicks. A total of 360 fertile eggs of uniform weight were randomly assigned to three groups. On day 17.5 of incubation, the eggs received IOF with either saline (control group), 200 μg SPCZ (SPCZ200 group), or 300 μg SPCZ (SPCZ300 group). The result showed that the SPCZ300 group significantly increased jejunal and ileal zinc content and chick hatching weight (p < 0.05). The SPCZ200 and SPCZ300 significantly reduced jejunal malondialdehyde (MDA) and hydrogen peroxide concentrations, enhanced ileal superoxide radical scavenging capacity and decreasing MDA concentration (p < 0.05). Furthermore, IOF SPCZ significantly upregulated jejunal mucin 2 (MUC2), superoxide dismutase 1, and metallothionein 4 (MT4), while downregulating nuclear factor kappa-B p65 subunit (NF-κB p65) and lipopolysaccharide-induced TNF-alpha factor (p < 0.05). In the jejunum, the SPCZ200 group upregulated nuclear factor erythroid-derived 2–like 2, glutathione peroxidase 1, and catalase; SPCZ300 downregulated interleukin-8 and upregulated interleukin-4 (IL-4) (p < 0.05). In the ileum, IOF of SPCZ upregulated interleukin-10, IL-4, MT4, and downregulated NF-κB p65 and B-cell lymphoma 2 antagonist/killer 1 (p < 0.05). Additionally, SPCZ300 significantly downregulated interferon gamma, cysteinyl aspartate-specific proteinase-9, and cysteinyl aspartate-specific proteinase-3, while SPCZ200 upregulated MUC2 (p < 0.05). Overall, IOF of SPCZ enhances intestinal zinc deposition, alleviates oxidative damage, and regulates the expression of genes related to inflammation, barrier function, and apoptosis, thus improving intestinal function in chicks.