Abstract
This study was to evaluate the effect of supplementing the diet of broilers with Neolamarckia cadamba leaf extract (NCLE) on meat quality by evaluating antioxidant parameters and the expression of genes in the p38 mitogen-activated protein kinase/nuclear factor-erythroid 2-related factor 2/antioxidant responsive element (p38 MAPK/Nrf2/ARE) signaling pathway, coupled with LC-MS-based metabolomic analysis. A total of 480 one-day-old male broilers were randomly allocated to four treatment groups-a control (CON) group, which was fed a basal diet, and three NCLE treatment groups, which were fed the basal diet supplemented with 100, 200, or 400 mg/kg NCLE (N1, N2, and N3 groups, respectively) for 42 d. Compared with the CON group, meat quality was improved in the N2 and N3 groups, as evidenced by the higher pH(45min) (P < 0.05) and lower shear force (P < 0.05) in breast muscle (BM) and lower drip loss at 48 h (P < 0.05) in leg muscle (LM). Moreover, BM antioxidant capacity was significantly enhanced in the N3 group, characterized by an increase in the total antioxidant capacity (T-AOC), the concentrations of glutathione peroxidase (GSH-Px) and catalase (CAT), and the relative mRNA expression of p38 MAPK, extracellular-signal regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), Nrf2, CAT, and GSH-Px (P < 0.05). Similarly, LM in the N3 group displayed higher T-AOC, increased GSH-Px and CAT concentrations, reduced malonaldehyde contents (P < 0.05), and upregulation of the relative mRNA levels of JNK, Nrf2, heme oxygenase, CAT, and superoxide dismutase (SOD) (P < 0.05). Metabolomics analysis revealed that D-arabinono-1,4-lactone and lyso-PAF C-16-d4 were negatively correlated with shear force and cooking loss (P < 0.05) and displayed increased abundance in BM of the N3 group. L-Serine levels were upregulated while D-fructose 1,6-diphosphate contents were downregulated in the three NCLE groups. Finally, the differential metabolites in both BM and LM were involved in amino acid metabolism pathways. Our results indicated that NCLE supplementation improved meat quality by enhancing antioxidant enzyme activities, promoting the expression of genes in the p38 MAPK/Nrf2/ARE signaling pathway, and regulating amino acid metabolism. The optimal NCLE concentration was found to be 400 mg/kg.