Dynamic Changes and Comprehensive Evaluation of Agronomic Traits and Nutritional Quality of Cichorium intybus at Different Growth Stages

Under the background of a supply gap expansion for high-quality forage grass in China and the high degree of dependence on foreign countries, it is necessary to clarify the best feeding and harvesting period for <i>Cichorium intybus</i> in the temperate continental monsoon climate zone of Northern China. To achieve this goal, this study systematically explored the agronomic traits and nutritional quality of <i>Cichorium intybus</i> during the nutritional period (June-July), flowering period (July-August), and fruiting period (August-September) in the Hohhot experimental base. We measured agronomic indexes, such as the plant height and basal stem, and nutrients, such as the dry matter (DM) and crude protein (CP), and calculated the total digestible nutrients (TDN) and other feeding value indexes. The results showed that the plant height of <i>Cichorium intybus</i> increased from 54.60 cm in the vegetative stage to 204.10 cm in the fruiting stage, and the fresh grass yield increased from 8775.045 kg/hm² in the vegetative stage to 19,035.09 kg/hm² in the fruiting stage. The DM content of the stems and leaves was the lowest (stem: 8.73%; leaf: 14.04%), but the CP (leaf: 20.32%) and crude fat (EE, leaf: 5.02%) contents were the highest. The TDN was 66.78%, the relative feed value (RFV) was 255.61, the comprehensive membership function value was 0.54 for the stems and 0.60 for the leaves, and the feeding value was the best. WSC accumulation was significant during the flowering stage; the fiber content of the DM (stem: 20.52%; leaf: 20.31%) and the acid detergent fiber (ADF, stem: 42.43%) were the highest during this stage; and the CP decreased to 10.97%. A correlation analysis showed that the plant height and stem diameter were significantly positively correlated with the yield and fiber accumulation. This study confirmed that the nutritional period was the best harvest period for obtaining high-protein and high-digestibility forage, and the fruiting period was suitable for processing hay or silage. These results provide a scientific basis for the large-scale feed development of <i>Cichorium intybus</i>.