Stevia extract improves broiler breast meat quality via regulating the glycerophospholipid metabolism and enhancing endoplasmic reticulum and mitochondrial homeostasis.

This study aimed to investigate the effects of stevia extract (SE) on growth performance and meat quality of broilers and reveal possibly mechanisms. Four hundred Arbor Acres male broilers (1 d old, 40 ± 1 g) were randomly assigned to 5 treatments with 8 replicates of 10 broilers per replicate. Broilers in the control (CON) group were fed the basal diet, while broilers in the other 4 treatment groups were fed the basal diet supplemented with 50, 100, 150, and 200 mg/kg SE, respectively. Dietary supplementation with SE effectively improved breast meat quality and tended to increase average daily gain (ADG) in broilers. Compared with the CON group, 150 mg/kg SE reduced 48 h drip loss and peak shear force of breast muscle (P < 0.05). Both 150 and 200 mg/kg SE decreased total cholesterol (TC) and triglyceride (TG) contents, while 100 and 150 mg/kg SE reduced malondialdehyde (MDA) concentration in breast muscle (P < 0.05). SE altered fatty acid (FA) composition: 150 mg/kg SE decreased the proportion of C24:0, and 200 mg/kg SE decreased C22:6n3 (P < 0.05). Linear regression analysis identified 150 mg/kg as the optimal SE level for meat quality improvement, which also downregulated FASN and ACACA mRNA expression (P < 0.05). Untargeted metabolomics revealed that 150 mg/kg SE modulated glycerophospholipid metabolism. Further validation confirmed that 150 mg/kg SE increased phospholipid (PL) content in breast muscle and improved endoplasmic reticulum (ER) and mitochondrial (MT) homeostasis. These changes were accompanied by reduced mRNA and protein expression of ER stress biomarkers (GRP78, PERK, IRE1, XBP1) and the MT chaperone HSP60 (P < 0.05). In conclusion, SE improves broiler breast meat quality via regulating the glycerophospholipid metabolism and enhancing endoplasmic reticulum and mitochondrial homeostasis. Regression analysis in this study indicates that the optimal SE supplementation amount for broilers is 150 mg/kg.