Energy and Nitrogen Provided by Native Herbage to Sheep Grazing in Alpine Grasslands of the Qinghai-Tibetan Plateau

In Alpine pasturelands animals switch from higher land for summer and autumn grazing to lower land for winter and spring grazing. A grazing experiment using nine Gansu Alpine Merinos was carried out in Alpine grassland on the Qinghai-Tibetan plateau. Results for the quality of consumed herbage from the autumn pasture showed that the Digestible Energy (DE), Crude Protein (CP) content and CP:DE ratio were 9.15 MJ kg(-1) 10.8 g/100 g and 11.8 g MJ(-1), respectively and the CP level and the CP:DE ratio were optimal for nitrogen utilization. The dry matter intake changed significantly with seasons (p<0.05). For sheep grazing on winter pasture, the actual metabolizable energy intake was lower than maintenance requirements with a negative nitrogen balance (p<0.05), supplements should include both energy and protein feed. While grazing on spring pasture, sheep should be supplemented with energy feed expected to improve N utilization.