Effects of dandelion on the quality and antioxidant activity of alfalfa silage

Dandelion was added to alfalfa silage at the rates of 0 (control group, CK), 2%, 4%, 6%, and 8%, with four replicates in each group. After 60 d of fermentation, the nutritional composition, fermentation quality, and antioxidant activity of the silage were determined. The results showed that, compared with CK, the dry matter (DM) and crude extract (EE) contents in the 4% group increased significantly and were 37.85% and 2.08%, respectively. The contents of EE and water-soluble carbohydrate (WSC) in the 6% group also increased significantly and were 2.27% and 6.52%, respectively. The contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in the 6% and 8% groups decreased significantly, and were 37.82% and 32.17% for NDF and 34.85% and 30.12% for ADF, respectively. In terms of fermentation quality, the pH and propionic acid (PA) content of the silage in all dandelion supplemented groups decreased significantly, whereas the content of acetic acid (AA) in all dandelion supplemented groups increased significantly and were above 1.00%. The content of lactic acid (LA) and the number of lactic acid bacteria (LAB) in the 4% group increased significantly and were 4.85% and 7.19 lg (cfu·g⁻¹), respectively, whereas ammonia nitrogen (NH₃-N) content decreased significantly and was 2.46%. For antioxidant activity, the flavonoid content in the 8% group was significantly increased to 1.37%. The total phenol and total polysaccharide contents and glutathione peroxidase (GSH-Px) activity in the 4%, 6%, and 8% groups were also significantly increased. The superoxide dismutase (SOD) activity of silage in the 6% group was significantly increased to 241.37 U·mg⁻¹, whereas the DPPH scavenging rate of silage in the 2% and 6% groups was significantly increased and both were above 90%. The total antioxidant capacity (T-AOC) of silage in the 2%, 4%, and 8% groups were also significantly increased and were 0.51, 0.60 and 0.43 mmol·L⁻¹, respectively. Principal component analysis and comprehensive score ranking showed the following order: 6% group > 4% group > 2% group > 8% group > CK. In summary, the nutritional quality, fermentation quality, and antioxidant activity of alfalfa silage were the best when dandelion was added at the rate of 6.0%.