Influence of Altitude on Nutritional Compositions of Wild Native Elymus on Qinghai-Tibetan Plateau of China

Wild native Elymus(Elymus dahuricus) is one of the most important and valuable forage grass on Qinghai-Tibetan Plateau(QTP) pasture of China.It mainly distributes above sea-level of 1 700 to 3 000 m on the QTP.The objective of this study was to investigate how the nutritive composition of Elymus responsed to the changes of altitude in local environments.Two test sites located at Minghe and Huangzhong counties, in which four sampling plots were arranged with sea levels of 1 714, 1 872, 2 097 and 2 185 m in Minhe County, while other four in Huangzhong County were with sea-level of 2 560, 2 613, 2 668 and 2 775 m.The whole plants of Elymus during anthesis stage were collected from all the plots for determining the indexes of crude protein(CP), crude fat(CF), neutral detergent fiber(NDF), acid detergent fiber(ADF), crude ash(ASH), calcium(Ca) and phosphorus(P).The results showed that the content of CP, crude ash and Ca changed irregularly corresponding to the altitude in the two counties, but significant higher with CP(1.09%), Ash(0.33%) and Ca(0.34%) in the low altitude areas(1 714-2 185 m) than those in the high altitude areas.NDF and ADF in the low altitude areas were significantly lower by 5.35% and 2.61% compared with those in the high altitude areas.There was no significant difference of CF as well as P in plant from different altitudes.Comprehensive evaluation revealed that superior nutritional composition of Elymus dahuricus presented at the sampling plots of altitude of 1 714 m in Minhe County.