Abstract: The aim of this study was to compare the effect of sowing time on the forage yield and nutrient composition of small grain planted in the Loess Plateau. Broomcorn millet, oat and rye were sown into fallow land in early fall and the vegetative parts were harvested as fodder grass. The forage yields, tiller densities, plant heights and fiber contents of three crops declined with delayed sowing time. Broomcorn millet had the highest forage yield and cellulose content, whereas rye was the lowest ones. The crude protein contents of three crops (CP) increased gradually with delayed sowing time and the CP contents of oat and rye were slightly higher than that of Broomcorn millet. The crude fat contents of these vegetative parts were about 1.4%~3.5%. The nutritional content of oat appeared to increase when sowing time was delayed. Broomcorn millet had the highest crude fat content when sown on July 21, while it had the lowest one when sown on A significantly higher than that of broomcorn millet. The soluble carbohydrate contents of oat and rye reduced with delayed sowing time, while that of broomcorn millet gradually increased in the range of 5%~10%. The NDF content of broomcorn millet (50%~55%) was significantly higher than that of oat and rye (30%~33%). The ADF content of broomcorn millet (17%~21%) reduced when sowing time was delayed. And the ADF contents of oat and rye was around 12%~14%. The crude protein, soluble carbohydrate, crude fat, crude fiber and gross energy yields of three crops per unit cultivated land all declined rapidly with delayed sowing time. According to the evaluation method of improved forage grass level, the vegetative parts of the three small grain crops sown in fall ranked as an above average level in forage quality. Broomcorn millet and oat scored higher than rye. Therefore, the two grain crops are suitable for promotion in this region.

摘要： 利用黄土高原秋闲田，在夏末秋初种植糜子（Panicum miliaceum）、燕麦（Arrhenatherum elatius）和黑麦（Secale cereale）收获营养体用作饲草，并比较播种时间对小谷物牧草产量和营养成分的作用。结果表明：3种小谷物的产草量、分蘖密度、株高、纤维素含量随播种时间延迟呈下降趋势；3种小谷物产草量约0.3~1.6 t·hm^-2，纤维素含量约2%~11%，均为糜子最高，黑麦最低。小谷物的粗蛋白含量约10%~15%，随播种延迟而逐渐升高，燕麦和黑麦略高于糜子。小谷物营养体粗脂肪含量约1.4%~3.5%；燕麦营养体中的含量随播种延迟呈增加趋势；糜子在8月1日播种最低，7月21日播种最高；播种时间对黑麦营养体的粗脂肪含量没有影响；黑麦和燕麦明显高于糜子。燕麦和黑麦的可溶性碳水化合物随着播种时间延迟而降低，糜子则逐渐升高，在5%~10%之间变动。糜子营养体中性洗涤纤维含量约50%~55%，显著高于燕麦和黑麦的30%~33%。糜子酸性洗涤纤维含量约17%~21%，随播种时间延迟而降低；燕麦和黑麦约12%~14%。单位面积耕地3种小谷物的粗蛋白、可溶性碳水化合物、粗脂肪、粗纤维和总能产量均随播种时间推迟而迅速下降。根据改进的牧草饲用等级评价方法，3种秋播小谷物的营养体均为中等到上等牧草，糜子和燕麦的得分高于黑麦，适合在该区域推广。

关键词: 燕麦, 黑麦, 糜子, 牧草产量, 秋闲田, 黄土高原