Optimization of Alfalfa-Based Mixed Cropping with Winter Wheat and Ryegrass in Terms of Forage Yield and Quality Traits

Forage has a significant association with animal nutrition because it is an essential part of milk and meat production in the livestock industry. Thus, for the production of high-quality forage, cereal–legume mixed cropping is an efficient method for meat and milk production in the livestock sector. In a two-year experiment between 2020 and 2021, the forage yield, nutritional compositions, amino acid profile, and forage quality were evaluated in the mixed cropping of winter wheat and ryegrass with alfalfa. In this study, a split-plot design with a randomized block design was employed with three sampling replicates. Cultivars were harvested at three maturity stages, namely, flowering, milk, and soft dough, depending on the wheat growth stage. The experimental results show that wheat 2 (Baomai 9)–alfalfa and ryegrass–alfalfa mixed cropping produced higher fresh biomass output than mono-cropping of wheat and ryegrass harvested at the flowering stage. Furthermore, the dry matter (DM) percentage range increased from 20.18% to 36.39%. By contrast, crude protein, crude fiber, neutral detergent fiber, and acid detergent fiber were higher at the flowering stage than at other harvesting stages with DM values of 14.28%, 34.12%, 55.06%, and 32.55%, respectively. Ryegrass–alfalfa mixing yielded higher values of mineral compositions, and T5 (Baomai 9–alfalfa) generally achieved more extraordinary amino acid compositions. The results demonstrate that wheat and ryegrass with alfalfa mixed cropping, and harvesting at the flowering period produces high-quality forage. Additionally, mixed cropping with alfalfa remarkably affected forage quality parameters, while mixed cropping of wheat cultivar 2 (Baomai 9) and alfalfa obtained the highest dry matter intake, digestible dry matter, relative feed value, total digestible nutrient, relative forage quality, and quality index values of 2.56, 68.54, 136.49, 60.50, 127.41, and 1.69, respectively. Thus, the mixed-cropping of wheat and ryegrass with alfalfa forage is recommended for its maximized quality forage production and nutritional values in livestock feedstuff.