Effects of growth years and cutting times on nutrient composition and digestibility of cultivated Glycyrrhiza uralensis

To determine the effects of cutting time on the yield, nutritional quality, and digestibility of Glycyrrhiza uralensis, its growth and development characteristics, grass yield, nutritional quality, and digestibility were measured and analyzed under different cutting treatments in the second and third years of planting. The results showed that with increasing growth years, the plant height, stem diameter, stem-to-leaf ratio, fresh hay yield, and fresh-to-dry ratio of licorice of different reproductive ages showed an upward trend, and the total number of branches showed a downward trend. The contents of crude protein, crude fat, and crude ash in dry matter showed a downward trend; contents of neutral detergent fiber, acid detergent fiber, and acid detergent lignin increased; whereas the 48 h dry matter digestibility decreased. Plant high accumulation, stem diameter accumulation, branch number accumulation, and total grass yield of multiple cuttings were significantly higher than those of the single cutting. The crude protein and crude ash contents of hay after two and three cuttings were significantly higher than those of the single cutting (P < 0.05). As the cutting time increased, the contents of neutral detergent fiber, acid detergent fiber, lignin, and total tannin in hay decreased significantly, whereas the contents of coumarin, glycyrrhizic acid, glycyrrhizin, and 48 h dry matter digestibility of hay increased significantly. In summary, multiple cuttings in the Korla area can improve the yield and nutritional quality of licorice grass compared with a single cutting. Multiple cuttings are a suitable management measure for this area.