本试验旨在探讨华北农牧交错带紫花苜蓿、棘豆、草木樨和野豌豆4种主要豆科牧草不同生育期营养价值变化规律。利用常规化学成分分析、体外消化技术和体外发酵产气技术测定4种豆科牧草盛花期和结实期的主要营养成分、体外消化率和瘤胃微生物体外发酵产气量。结果表明：开花期草木樨、紫花苜蓿的粗蛋白质含量差异不显著(P>0.05)，与棘豆和野豌豆相比差异显著(P<0.05)，野豌豆与棘豆粗蛋白质含量差异显著(P<0.05)，棘豆、紫花苜蓿、草木樨、野豌豆的粗蛋白质含量随生育期延长而下降，差异极显著(P<0.01)；结实期与开花期相比，中性洗涤纤维和酸性洗涤纤维的含量有增长趋势(P>0.05)，4种牧草的干物质体外消化率（DMD）、中性洗涤纤维体外消化率（NDFD）、酸性洗涤纤维体外消化率（ADFD）呈下降趋势(P>0.05)；棘豆、紫花苜蓿结实期和开花期的24 h产气量差异显著(P<0.05)，只有棘豆2个生育期的48 h产气量差异显著(P<0.05)，4种牧草2个生育期的理论最大产气量差异不显著(P>0.05)，4种豆科牧草结实期的延滞期相比开花期有增长趋势(P>0.05)。综上所述，本研究所选4种豆科牧草结实期营养价值低于开花期。

The objective of this study was to evaluate the nutritional values of four kinds of leguminous forages Vicia sepium Linn, Oxytropis glabra DC, Medicago sativa Linn, and Melilotus officinalis Pall grown in the agro-pastoral ecotone of North China in different growing periods. The chemical composition, in vitro digestibility and in vitro gas production parameters for these forage samples were determined by proximate analysis, in vitro digestion and in vitro gas production techniques. The results showed that the crude protein (CP) contents of Melilotus officinalis Pall and Medicago sativa Linn at the flowering stage were not significantly different (P>0.05), but they were significantly different from those of Oxytropis glabra DC and Vicia sepium Linn (P<0.05). There was a significant difference in CP content between Oxytropis glabra DC and Vicia sepium Linn (P<0.05). The CP contents of Oxytropis glabra DC, Medicago sativa Linn, Melilotus officinalis Pall and Vicia sepium Linn declined significantly as the growing period went by (P<0.01), whereas the contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were increased at the seeding stage compared with the flowering stage (P>0.05). The in vitro digestibility of dry matter, NDF and ADF were reduced as the growing period went by (P>0.05). There was a significant difference in gas production in 24 h for Oxytropis glabra DC and Medicago sativa Linn at the flowering stage compared with the seeding stage (P<0.05), whereas there was a significant difference in gas production in 48 h only for Oxytropis glabra DC between the two stages (P<0.05). No difference was found in total gas production of the four kinds of forages (P>0.05). There was a rising tendency for the lag time of the four leguminous forages at the seeding stage compared with the flowering stage (P>0.05). In conclusion, the nutritional values of the leguminous forages involved in this study at the seeding stage are lower than those at the flowering stage. ［Chinese Journal of Animal Nutrition，2011，23（3）：387-394］