The optimal cutting date of common vetch forage Lanjian No.1 in Xiahe Region, Gansu

The field trial was conducted in Xiahe Region of Gansu Province. A randomized complete block design was applied to investigate the optimal cutting date of Lanjian No.1. Sampling was made during the periods of squaring, flowering, podding and mature to measure the content of crude protein (CP), water soluble carbohydrate (WSC), crude fat (CF), neutral detergent fiber (NDF), mineral elements and dry matter yield. The result showed that CP contents all reached the first level of the American forage standard. The content of CP was the highest while WSC, CF and NDF were of the medium level during the mature period. Mineral elements P, K, Na, Mg and Zn in Lanjian No.1 could satisfy the basic needs of livestock on alpine grassland. Grey relational analysis and weight assignment method were adopted for the comprehensive evaluation of dry matter yield, CP, WSC, CF, NDF and mineral elements levels. It was found that comprehensive evaluation index was the highest in the mature period. Thus, the optimal cutting date of Lanjian No.1 should be mature period.