Background: Exploring the hypoxia adaptation mechanism of Tibetan chicken is of great significance for revealing the survival law of Tibetan chicken and plateau animal husbandry production. To investigate the hypoxia adaptation of Tibetan chickens (TBCs), an integrative metabolomic-transcriptomic analysis of the liver on day 18 of embryonic development was performed. Dwarf laying chickens (DLCs), a lowland breed, were used as a control. Results: A total of 1,908 metabolites were identified in both TBCs and DLCs. Energy metabolism and amino acid metabolism related differentially regulated metabolites (DRMs) were significantly enriched under hypoxia. Important metabolic pathways including the TCA cycle and arginine and proline metabolism were screened; PCK1, SUCLA2, and CPS1 were found to be altered under hypoxic conditions. In addition, integrated analysis suggested potential differences in mitochondrial function, which may play a crucial role in the study of chicken oxygen adaptation. Conclusions: These results suggest that hypoxia changed the gene expression and metabolic patterns of embryonic liver of TBCs compared to DLCs. Our study provides a basis for uncovering the molecular regulation mechanisms of hypoxia adaptation in TBCs with the potential application of hypoxia adaptation research for other animals living on the Qinghai-Tibet plateau, and may even contribute to the study of diseases caused by hypoxia.

Compared to commercial breeds, Chinese local pig breeds have a greater ability to digest dietary fiber, which may be due to differences in intestinal microbiota. In this study, we fed Ding’an and DLY pigs high and low levels of dietary fiber, respectively, to investigate factors contributing to high dietary fiber adaption in Ding’an pigs. Twelve Ding’an pigs and DLY pigs were randomly divided into a 2 (diet) × 2 (breed) factorial experiment (n = 3). Compared with commercial pigs, Ding’an pigs have a stronger ability to digest dietary fiber. Prevotella was more prevalent in Ding’an pigs than in DLY pigs, which may be an important reason for the stronger ability of fiber degradation in Ding’an pigs. When the effects of feed and breed factors are considered, differences in abundance of 31 species and 14 species, respectively, may result in a greater ability of fiber degradation in Ding’an pigs. Among them, Prevotella. sp. CAG:520 may be a newly discovered bacterium related to fiber degradation, which positively correlated with many fiber-degrading bacteria (r > 0.7). We also found that the concentration of plant metabolites with anti-inflammatory and antioxidant effects was higher in the colonic chyme of Ding’an pigs after increasing the fiber content, which resulted in the downregulated expression of inflammatory factors in colonic mucosa. Spearman’s correlation coefficient revealed a strong correlation between microbiota and the apparent digestibility of dietary fiber (r > 0.7). The mRNA expressions of SLC16A1, PYY, and GCG were significantly increased in the colonic mucosa of Ding’an pigs fed on high-fiber diets, which indicates that Ding’an pigs have an enhanced absorption of SCFAs. Our results suggested that an appropriate increase in dietary fiber content can reduce the inflammatory response and improve feed efficiency in Ding’an pigs, and differences in the intestinal microbial composition may be an important reason for the difference in the fiber degradation capacity between the two breeds of pigs.

Domestic chicken is an ideal model to study the relationship between lipid metabolism and environmental stress. However, the lipid composition of chicken embryonic brain under hypoxic conditions has not been systematically elucidated. We employed targeted lipidomics to comprehensively describe the alterations in the brain lipid profiles of embryonic day 18 TBCs and DLCs under hypoxia (13% O₂, HTBC18, and HDLC18) and normoxia (21% O₂, NTBC18, and NDLC18). Totally 1288 lipid species from 18 lipid classes were identified and screened for 47 (three up-regulated and 44 down-regulated) and 55 (10 up-regulated and 45 down-regulated) SDLs in HTBC18 compared to NTBC18 and HDLC18 compared to NDLC18, respectively. The five SDLs were shared between HTBC18 vs. NTBC18 and HDLC18 vs. NDLC18, including PI (16:0_20:3), PE (18:1_20:4), PC (20:0_22:5), PS (16:1_18:0) and PS (16:0_20:3), which were identified as candidate hypoxia-responsive lipids. Furthermore, the analysis of SDLs’ metabolic pathways revealed that glycerophospholipid metabolism was the most crucial. The present results provide insights into the dynamic composition of lipid in chicken embryo brains under hypoxic conditions.