Developing salt-alkali-tolerant and sustainable forage resources, while directionally improving meat quality and flavor through nutritional regulation, is of great importance for promoting the high-quality development of ruminant production. Based on this, the present study investigated the effects of replacing alfalfa hay with sesbania hay on growth performance, meat quality, and flavor-related metabolic networks in lambs.

A total of 40 healthy 3-month-old Australian × Hu crossbred ram lambs with similar initial body weight were selected and randomly assigned to five dietary treatments (n = 8 per group, individually housed) under isoenergetic and isonitrogenous conditions. The replacement levels of alfalfa hay by sesbania hay were 0% (CON), 25% (SC25), 50% (SC50), 75% (SC75), and 100% (SC100). At the end of the trial, growth performance, serum physiological, biochemical, and antioxidant indices, meat quality, amino acids, fatty acid precursors, and volatile flavor metabolites were systematically determined. Multi-omics correlation analysis and network topology analysis were further performed to comprehensively elucidate the dynamic patterns of nutritional precursors and volatile flavor metabolites in lamb meat.

Replacing alfalfa with sesbania at levels ranging from 0% to 100% had no adverse effects on lamb growth performance, while significantly enhancing antioxidant capacity, as evidenced by increased SOD and T-AOC levels, and improving the water-holding capacity of meat. Among all treatments, the SC75 group exhibited the most favorable coordinated advantages in meat quality, antioxidant status, and overall flavor performance.

Integrated multi-omics analysis suggested that sesbania substitution may contribute to the remodeling of lamb meat flavor through the following three aspects: (1) Endogenous flavor enhancement: Under antioxidant protection, muscle lipid composition was optimized, with an increased PUFA/SFA ratio reaching 0.54 in the SC75 group. Meanwhile, the formation of key lipid oxidation-related volatile compounds, such as hexanal, nonanal, and 1-octen-3-one, was promoted. (2) Reduction of potential off-flavor precursors at the source: Sesbania substitution reduced the metabolic activity associated with certain aromatic amino acids, including tryptophan and phenylalanine, suggesting a weakened basis for the formation of some nitrogen- and sulfur-containing potential off-flavor precursors. (3) Exogenous aroma contribution: Plant-derived aromatic compounds such as guaiacol and (+/-)-limonene were enriched in the high-replacement groups, indicating that essential oils and secondary metabolites from sesbania may participate in lamb flavor formation, thereby imparting more pronounced herbal, fruity, and smoky notes.

Further degree centrality and betweenness centrality network analyses revealed that sesbania substitution drove a systematic reconstruction of the meat flavor metabolic network. Overall, the network organization shifted from a structure relatively dominated by amino acid-related nodes in the control group to a new pattern jointly involving lipid oxidation products, certain sulfur-containing meaty aroma compounds, and plant-derived aromatic components. Among the treatments, the SC75 group showed better network coordination, whereas the SC100 group further strengthened the participation of plant-derived aromatic modules and lipid structural indices

Changes in forage nutritional composition can markedly affect the formation of lipid precursors, amino acid metabolism, and volatile flavor compounds in ruminant muscle. The present study demonstrated that replacing alfalfa with sesbania improved antioxidant status, enhanced meat quality, and reshaped the flavor metabolic network of lamb meat without compromising growth performance. On the one hand, sesbania substitution helped optimize fatty acid composition, increase the PUFA/SFA ratio, and promote the formation of key lipid-derived aroma compounds such as hexanal, nonanal, and 1-octen-3-one during relatively controlled lipid oxidation. On the other hand, several aromatic amino acid-related pathways were regulated, suggesting a reduced supply basis for some potential off-flavor precursors. In addition, the enrichment of plant-derived aromatic compounds from sesbania in muscle further enriched the herbal, fruity, and smoky flavor characteristics of lamb meat.

Notably, the multi-omics and network topology analyses indicated that sesbania substitution did not merely alter the abundance of individual metabolites, but rather promoted a systematic adjustment in the interactions between precursor substances and volatile products. With increasing replacement levels, the flavor network gradually shifted from a control pattern relatively centered on amino acid-related nodes toward a reconstructed state characterized by the joint participation of lipid oxidation products and plant-derived aromatic compounds. Among these, the SC75 group exhibited the best overall advantages in meat water-holding capacity, antioxidant status, and flavor network coordination, suggesting that a 75% replacement level may be the most appropriate ratio for balancing production performance, meat quality, and flavor characteristics.

Overall, S. cannabina appears to be a promising alternative forage for improving meat quality and modulating the chemical basis of lamb flavor, with the 75% replacement level showing the best overall performance.

Sesbania cannabina, Meat quality, Flavoromics, Volatile compounds, Antioxidant status, Fatty acids.