Determining the Optimal Harvesting Moment of Green Forage from Guizotia abyssinica Cultivated as a Catch Crop on Silage and Its Quality Form, Fresh or Wilted Green Material, in the Two Following Years

<i>Guizotia abyssinica</i> is currently being used for soil improvement; however, owing to its rapid growth and high productivity, it may have value as feed for ruminants, although this has not been well studied. Thus, this research aimed to evaluate the silage quality of <i>Guizotia abyssinica</i> grown during the short season (July-October) as a catch crop in northern Europe when harvested 58, 68, and 90 days after sowing (DAS) over two production years. Ensiled material was analyzed to compare silage quality for the three different DAS. Two factors were analyzed factorially in the experiment: the silage preparation year (2018 or 2019) and the form of the ensiled material (fresh or wilted). We used 36 replications, 18 for each variant of the experimental factor. Harvesting at 58 DAS resulted in unsatisfactory forage fermentability, even after wilting. At 68 DAS, silage quality was satisfactory, but the dry matter content before ensiling was below 20% for both fresh and wilted forage, indicating limitations for silage use without additional wilting for that DAS harvest time. Dry matter content and water-soluble carbohydrates consistently increased as harvest was delayed. Thus, the highest silage quality was obtained from forage harvested 90 DAS regardless of differences in dry matter content. Therefore, it is possible to prepare silage at lower temperatures when the wilting process is limited by environmental conditions.