Objective  Effect of silage time on nutrient contents of Cymbopogon citratus was studied.

  Method  Changes on the nutrients in C. citratus during silage was monitored periodically to determine the optimal fermentation period for cattle feeding.

  Result  After one month of silage, the protein and crude fiber in citronella increased significantly and peaked with the protein content rose from 5.48% to 6.64% and the crude fiber from 34.96% to 36.65%. In 2-4 months, the protein content became stable ranging from 6.32% to 6.39% before a significant decline, while the crude fiber remained at 34.23%-35.77% for 2-6 months. During the initial 4 months there was no significant changes on the calcium in citronella, but the content increased significantly in 5-6 month. For the first 5 months, the phosphorus content decreased initially followed by a slow incline to reach a peak in the 6^th month. Up till 3 months of silage, the fermented citronella was judged to have a Level 1 sensory score with maximized contents on amino acids, crude fat, and ash as well as a constantly high crude protein content. Afterward, however, the sensory score dropped to Level 2 with decreasing crude protein, amino acid, crude ash, and crude fat contents with a deteriorated quality.

  Conclusion  It appeared that 1-3 month of silage would allow citronella to reach the highest nutrient level and prolonged storage could considerably ill-affect the forage quality.