Seasonal variation and supplydemand analysis of manganese in alpine grazing grassland system

The content and seasonal changes of Mn in water, soil, edible grass (gained by fistula set on esophagus), wool and other organs such as plasma, liver, skeleton in sheep on Sanjiaocheng Sheep Farm of Qinghai Province from mid June to mid December were studied. The results indicated that Mn content in soil was higher in summer than that in autumn and winter but all were in lower threshold of normal level. In edible grass and sheep organs (except for liver), the order of Mn contents in different seasons was summer autumn winter, and it was insufficient in winter. Generally, in terms of soilforagesheep ecosystem, the Mn supply for sheep was insufficient in winter.