Zanthoxylum bungeanum leaf enhanced yolk color and egg flavor in laying hens by altering yolk lipid composition

The present study was conducted to investigate the effects of different levels of dietary Zanthoxylum bungeanum leaf (ZBL) on productive performance, egg quality, flavor, and yolk lipidomic of laying hens. In total, 640 healthy Lohmann Pink laying hens (age, 58 weeks) were randomly assigned to one of four treatment groups: control (CON), 1 % ZBL, 2 % ZBL, or 3 % ZBL. The entire experiment lasted for eight weeks. The results demonstrated that dietary supplementation with ZBL did not compromise the laying rate in laying hens (P > 0.05). The egg yolk color had increased with ZBL levels (P < 0.05). As compared to the CON group, 3 % ZBL strengthened sourness, richness, saltiness and bitterness of E-tongue analysis and strengthened overall acceptance of sensory evaluation (P < 0.05). In total, 1,533 lipid species in 33 subclasses were detected, including 392 differential lipid species between the CON and 3 % ZBL groups. Glycerophospholipids and sphingolipids were the most abundant lipid species. Principal component analysis and orthogonal partial least squares discriminant analysis showed that the addition of 3 % ZBL resulted in significant changes to the lipid profiles of egg yolks. Moreover, "sphingolipid metabolism" and "glycerophospholipid metabolism" were the key metabolic pathways altered by the addition of 3 % ZBL. The content of sphingolipids in egg has been found to be strongly positively correlated with the saltiness, sourness, and bitterness of eggs. In conclusion, dietary supplementation with ZBL did not reduce the laying rate, but enhanced yolk color and flavor. Sphingolipids were key lipids that influence the flavor of eggs.