BACKGROUND Vitamin B12 plays an important role in lipid, protein, carbohydrate and nucleic acid metabolism. We investigated the effect of supplementing layers’ diets with different vitamin B12 levels on liver metabolism using a liquid chromatography–mass spectrometry‐based metabolomic approach to observe and analyse wide‐target metabolomics in the liver. RESULTS We assigned hens to three groups, namely blank control group without vitamin B12 diet (BCG), normal control group with 25 μg kg−1 vitamin B12 (NCG) and vitamin B12 supplement group I with 100 μg kg−1 vitamin (VBSG I). The VBSG I group layers had higher (P < 0.05) vitamin B12 concentration than those from other groups. The egg yolk vitamin B12 concentration increased (P < 0.01) with the increasing vitamin B12 dietary supplemental level. Between the NCG versus BCG, VBSG I versus BCG, and VBSG I versus NCG groups, 11, 20 and 11 metabolites were significantly changed, respectively. The KEGG pathway of vitamin B6 metabolism was significantly impacted in the NCG layers than those from BCG; seven and five pathways were significantly impacted in the VBSG I layers compared with those from BCG and NCG, including pyrimidine metabolism, vitamin B6 metabolism, glycerophospholipid metabolism, etc. CONCLUSION We concluded that 25 μg kg−1 vitamin B12 supplementation in corn–soybean meal‐based layer diet increased the egg yolk vitamin B12 concentration and impacted the vitamin B6 metabolic pathway, and 100 μg kg−1 of it increased the egg yolk and liver vitamin B12 concentrations and impacted vitamin B6, lipid, nucleic acid and amino acid metabolic pathways. © 2022 Society of Chemical Industry.

High-through chromosome conformation capture (Hi-C) technique is widely used to study the functional roles of the three-dimensional (3D) genome architecture of genomes. However, knowledge of 3D genome structure and its dynamic during extreme environments adaption remain poor. Here we characterized 3D genome architectures with Hi-C technique for chicken liver cells. By comparing Lindian chicken (LDC) liver cells with Wenchang chicken (WCC) liver cells, we discovered that environmental adaption contributed to the switching of A/B compartments, the reorganization of topologically associated domains (TADs) and TAD boundaries in both liver cells. Besides, analysis of the switching of A/B compartments combined with liver transcriptome revealed the corresponding changes of gene expression were strongly associated with extreme environment adaption-related pathways, including Tight junction, Notch signaling pathway, Vascular smooth muscle contraction, RIG-I-like receptor signaling pathway and Glycosphingolipid biosynthesis pathways. This study advanced our understanding of evolutionary role of chicken 3D genome architecture and their significance in genome activity and transcriptional regulation.