Abstract: The objective of this study was to investigate the feeding and fermentation quality of Italian ryegrass (Lolium multiflorum) cut at different growth stages and wilted for various lengths of time, so as to formulate scientifically based guidelines for optimal wilting time when making silage. One Italian ryegrass variety, Musashi, was used in this study, and there were six wilting treatments (0, 1, 2, 3, 4, 5 h) at booting and flowering stages, with the feeding quality and fermentation quality analyzed. The nonstructural carbohydrate (NSC) content decreased with time during wilting, but water soluble carbohydrate (WSC) which was the main component of NSC, showed an intital increase in WSC during the first hour of wilting to a high of 10.62% after 1 h, then declined, when cut at booting stage. When cut at flowering stage the WSC content during the wilting period increased to a high of 14.46% after 3 h and then decreased. Fermentation-related data for cutting at booting stage were: pH reached its lowest point, 4.05, after 3 h and then increased; the NH₃-N content decreased with increased wilting time; the lactic acid (LA) content initially increased and then decreased, with a high point of 8.49% after 3 h. Corresponding values for cutting at flowering stage were: the pH value increased with wilting time; NH₃-N content initially increased to a high of 2.03 mg/g after 2 h wilting; the LA content decreased slowly at first to 4.56% after 3 h wilting, and then sharply decreased to 1.38% after 5 h wilting. Considering that the ideal for silage making is higher WSC and LA content and lower pH and NH₃-N content, based on these data the optimal wilting time for Italian ryegrass at booting stage would be 3 h, while at flowering stage it would be 2 h.