Nutrition contents analysis of five kinds of main poisonous plants in Tibet natural grassland

The present study detected the conventional nutrients and mineral elements content of 5 kinds of poisonous plants including Astragalus strictus, Oxytropis kansuensis, Oxytropis sericopetala, Stellera chamaejasme and Ligularia rumicifolia in Tibet natural grassland during their different phenological phases using national standards. The results showed that the average crude protein contents were highest in the A. strictus and second highest in O. kansuensis which were more than 19%. For A. strictus, the contents of crude protein were highest in blooming period and lowest in preblooming period without significant difference between blooming period and fruiting period. For O. kansuensis, the contents of crude protein were highest in preblooming period and lowest in fruiting period without significant difference between preblooming and blooming period and fruiting period. The contents of crude fiber decreased in the following order: O. sericopetala, L. rumicifolia, A. strictus, O. kansuensis and S. chamaejasme and were highest in fruiting period and lowest in preblooming period. The contents of mineral elements, including Mg, Fe, Cu, Mn and Zn in all of the 5 tested plants were highest in preblooming period and were lowest in fruiting period, however, the content of Se was relatively higher in fruiting period. In conclusion, A. strictus and O. kansuensis may had rich nutritional and potential value for pasture whereas O. sericopetala, S. chamaejasme and L. rumicifolia had low nutritional value.