Comparative transcriptome analysis reveals mechanisms of restriction feeding on lipid metabolism in ducks.

Presently, excessive fat deposition is the main reason to limit the development of duck industry. In the production, the methods of restricted feeding (RF) were widely used to reduce the lipid deposition of ducks. The liver (L), abdominal adipose (AA), and subcutaneous adipose (SA) were the main tissues of lipid metabolism and deposition of ducks. However, the mechanisms of lipid metabolism and deposition of ducks under RF have not been fully clarified. In this study, in order to better understand the mechanisms of lipid metabolism and deposition in ducks under RF, a total of 120 male Nonghua ducks were randomly divided into a free feeding group (FF, n = 60) and RF group (RF, n = 60), then comparative transcriptomic analysis of L, AA, and SA between FF (n = 3) and RF (n = 3) ducks was performed at 56 d of age. Phenotypically, L, AA, and SA index of FF group was higher than that in RF group. There were 279, 390, and 557 differentially expressed genes (DEGs) in L, AA, and SA. Functional enrichment analysis revealed that ECM-receptor interaction and metabolic pathways were significantly enriched in L, AA, and SA. Lipid metabolism-related pathways including fatty acid metabolism, unsaturated fatty acid synthesis, and steroidogenesis were significantly enriched in AA and SA. Moreover, through integrated analysis weighted gene coexpression network (WGCNA) and protein-protein interaction network, 10 potential candidate genes involved in the ECM-receptor interaction and lipid metabolism pathways were identified, including 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), aldolase B (ALDOB), formimidoyltransferase cyclodeaminase(FTCD), phosphoenolpyruvate carboxykinase 1 (PCK1), tyrosine aminotransferase (TAT), stearoyl-CoA desaturase (SCD), squalene epoxidase (SQLE), phosphodiesterase 4B (PDE4B), choline kinase A (CHKA), and elongation of very-long-chain fatty acids-like 2 (ELOVL2), which could play a key role in lipid metabolism and deposition of ducks under RF. Our study reveals that the liver might regulate the lipid metabolism of abdominal adipose and subcutaneous adipose through ECM-receptor interaction and metabolic pathways (fatty acid metabolism, unsaturated fatty acid synthesis, and steroid synthesis), thus to reduce the lipid deposition of ducks under RF. These results provide novel insights into the avian lipid metabolism and will help better understand the underlying molecular mechanisms.