The change of forage supplies and animal requirements andits regulation in the Gannan pastoral area A case of Azi Animal Husbandry Experiment Area

The Gannan Pastoral Area is not only an important animal husbandry production base, but also an important water conservation of the upper reaches of the Yellow River in China. Overgrazing causes the degradation of natural grassland, which seriously affects the sustainable development of this pastoral area. Taken the Animal Husbandry Experiment Area of Maqu County as an example, the changes of natural grassland production and carrying capacity of grazing livestock from 2008 to 2009 were discussed in this study. This study indicated that the average month grassland yield in 2009 increased the 185.0 kg/ha when compared to those in 2008 and the carrying capacity of grassland in 2009 was 6 616.4 sheep unit and decreased the 2 109.5 sheep unit when compared to those in 2008. This study showed that the relationship between forage supplies and animal requirements was out of balance with 33% overgrazing in the study area. Some effective measures were proposed in this study to balance the relationship between forage supplies and animal requirements, including livestock quantity control, increased of fodder, storage forage with cutting.