以木薯（Manihot esculenta Crantz）品种‘华南7号’（‘South China 7’）、‘华南9号’（‘South China 9’）和‘华南205号’（‘South China 205’）为研究对象，分别对种植后90、120、150、180和210 d的3个木薯品种嫩茎叶中氢氰酸、总黄酮及主要营养成分含量的变化进行了分析；在此基础上，明确供试3个品种嫩茎叶作为饲料的最佳采收期。结果表明：随种植后时间延长，3个品种嫩茎叶中的氢氰酸和总黄酮含量变化均呈波动趋势，其中，‘华南7号’嫩茎叶的氢氰酸含量在种植后150和210 d显著降低（分别为347.843和320.507 mg·kg^-1），‘华南9号’嫩茎叶的氢氰酸含量在种植后150 d最低（313.643 mg·kg^-1），‘华南205号’嫩茎叶的氢氰酸含量在种植后210 d最低（75.103 mg·kg^-1）；‘华南7号’和‘华南205号’嫩茎叶的总黄酮含量在种植后120 d最高（分别为1.963％和1.917％），而‘华南9号’嫩茎叶的总黄酮含量则在种植后210 d最高（1.801％）。不同生长期3个木薯品种嫩茎叶的粗蛋白质和粗灰分含量均符合相关动物饲料的标准，而总磷含量均较低。其中，‘华南7号’嫩茎叶的粗蛋白质、粗脂肪、粗纤维、粗灰分和总钙含量在种植后150 d相对较高，分别为25.273％、7.687％、23.077％、7.157％和1.660％，其无氮浸出物含量（26.823％）相对较低；‘华南9号’嫩茎叶的上述5种营养成分含量在种植后120 d相对较高，分别为28.050％、6.990％、21.557％、8.467％和1.493％，其无氮浸出物含量（24.723％）相对较低；‘华南205号’嫩茎叶的粗蛋白质、粗脂肪和粗灰分含量在种植后120 d相对较高，分别为24.273％、7.080％和7.633％，其粗纤维（18.470％）、无氮浸出物（32.037％）和总钙（1.323％）含量相对较低。综合分析结果显示：‘华南7号’、‘华南9号’和‘华南205号’嫩茎叶作为饲料的最佳采收时间分别为种植后150、120和120 d。

Taking cultivar ‘South China 7’， ‘South China 9’ and ‘South China 205’ of Manihot esculenta Crantz as research objects， changes in contents of hydrocyanic acid， total flavonoids and main nutrient components in tender stems and leaves of three cultivars after cultivated for 90， 120， 150， 180 and 210 d were analyzed， respectively. On this basis， the optimal harvesting time of tender stems and leaves of three tested cultivars using as forages was determined. The results show that with prolonging of time after cultivated， changes in contents of hydrocyanic acid and total flavonoids in tender stems and leaves of three cultivars show a fluctuation tendency， in which， hydrocyanic acid content in tender stems and leaves of ‘South China 7’ decreases significantly after cultivated for 150 and 210 d with 347.843 and 320.507 mg·kg^-1， respectively， that of ‘South China 9’ is the lowest after cultivated for 150 d with 313.643 mg·kg^-1, and that of ‘South China 205’ is the lowest after cultivated for 210 d with 75.103 mg·kg^-1； total flavonoids contents in tender stems and leaves of ‘South China 7’ and ‘South China 205’ are the highest after cultivated for 120 d with 1.963％ and 1.917％， respectively， while that of ‘South China 9’ is the highest after cultivated for 210 d with 1.801％. Contents of crude protein and crude ash in tender stems and leaves of three cultivars of M. esculenta at different growth stages are in accord with related animal forage standards， while their total phosphorus contents are low. In which， contents of crude protein， crude fat， crude fiber， crude ash and total calcium in tender stems and leaves of ‘South China 7’ are relatively high after cultivated for 150 d with 25.273％， 7.687％， 23.077％， 7.157％ and 1.660％， respectively， its nitrogen free extract content （26.823％） is relatively low. Contents of above five nutrient components in tender stems and leaves of ‘South China 9’ are relatively high after cultivated for 120 d with 28.050％， 6.990％， 21.557％， 8.467％ and 1.493％， respectively， its nitrogen free extract content （24.723％） is relatively low. Contents of crude protein， crude fat and crude ash in tender stems and leaves of ‘South China 205’ are relatively high after cultivated for 120 d with 24.273％， 7.080％ and 7.633％， respectively， its contents of crude fiber （18.470％）， nitrogen free extract （32.037％） and total calcium （1.323％） are relatively low. The comprehensive analysis result shows that the optimal harvesting time of tender stems and leaves of ‘South China 7’， ‘South China 9’ and ‘South China 205’ using as forages is after cultivated for 150， 120 and 120 d， respectively.