摘要Methionine(Met)is an essential and first limiting amino acid in the poultry diet that plays a significant role in chicken embryonic development and growth.The present study examined the effect of in ovo injection of DL-Met and L-Met sources and genotypes on chicken embryonic-intestinal development and health.Fertilized eggs of the two genotypes,TETRA-SL layer hybrid(TSL)-commercial layer hybrid and Hungarian Partridge colored hen breed(HPC)-a native genotype,were randomly distributed into four treatments for each genotype.The treatment groups include the following:1)control non-injected eggs(Noln);2)saline-injected(Saln);3)DL-Met injected(DLM);and 4)L-Met injected(LM).The in ovo in-jection was carried out on 17.5 d of embryonic development;after hatching,eight chicks per group were sacrificed,and the jejunum was extracted for analysis.The results showed that both DLM and LM groups had enhanced intestinal development as evidenced by increased villus width,villus height,and villus area(P＜0.05)compared to the control.The DLM group had significantly reduced crypt depth,gluta-thione(GSH)content,glutathione S-transferase 3 alpha(GST3),occludin(OCLN)gene expression and increased villus height to crypt depth ratio in the TSL genotype than the LM group(P＜0.05).The HPC genotype has overexpressed insulin-like growth factor 1(IGF1)gene,tricellulin(MD2),occludin(OCLN),superoxide dismutase 1(SOD1),and GST3 genes than the TSL genotype(P＜0.05).In conclusion,these findings showed that in ovo injection of Met enhanced intestinal development,and function,with ge-notypes responding differently under normal conditions.Genotypes also influenced the expression of intestinal antioxidants,tight junction,and growth-related genes.