Abstract
Methionine (Met) plays a substantial role in poultry due to its involvement in several pathways, including enhancing antioxidant status and improving growth performance and health status. This study examined how in ovo feeding of Met affects hatching performance, antioxidant status, and hepatic gene expression related to growth and immunity in the TETRA-SL LL hybrid (TSL) commercial layer and Hungarian partridge colored hen (HPC) indigenous genotypes. The eggs were injected with saline, DL-Met, and L-Met on 17.5 days of embryonic development. The results showed that the in ovo feeding of DL-Met significantly increased the hatching weight and ferric reducing the ability of the plasma (FRAP) compared with L-Met. The in ovo feeding of either Met source enhanced the liver health and function and hepatic antioxidant status of the chicks. The genotype's differences were significant; the TSL genotype had better hatching weight, an antioxidant defense system, and downregulated growth-related gene expression than the HPC genotype. In ovo feeding of either Met source enhanced the chicks' health status and antioxidant status, and DL-Met improved the hatching weight of the chicks more than L-Met. Genotype differences were significantly evident in the responses of growth performance, antioxidant status, blood biochemical parameters, and gene expression to Met sources.