中文摘要：

草地畜牧业的理论基础是畜牧学知识。草地畜牧业的核心是生产畜产品．包括牲畜的肉或毛皮或奶或羔犊。生产过程是牲畜食草转化为畜产品。牲畜生长生产是一个自然过程，也是一个草地饲草数量与饲草质量的时间函数过程。草地饲草数量与质量是一个年际间的动态过程、也是一个年度内的动态过程，因此，草地牲畜生长生产是一个取决于饲草数量与饲草质量的时间动态过程。草地饲草生长过程和繁殖过程对放牧的反应及草地净产量动态过程是理解草地放牧的基础。放牧是草地管理工具。同时。放牧也是生产牲畜的途径，在草地放牧的基础上．优化草地牲畜生产是积极的草地管理策略与措施。科学合理放牧包括3项要素、4种行为．优化草地牲畜生产包括一年内饲草供应策略及其与们草生长的匹配、放牧与饲喂的协调。草地养作是基于苹地健康维持、饲草数量和营养动态、牲畜生长过程和生长需要。优化草地牲畜生产的过程及其工艺．为保护草地资源利用的基础和保证。

英文摘要：

The central point of grassland farming is animal production by grazing and/or feeding. Animal growth is a natural dynamics, which was affected annually by the quality and quantity of forage and environment. Therefore, annual dynamics in the producing process of animal has great significance in animal and grassland management. Lots of factors should be considered, such as three action factors in grazing： intensity, frequency and timing, and four behavior factors in grazing： physical damage, trampling, unbalanced nutrition and saliva. In the case, optimizing feeding on grassland by grazing and/or by supplement is an active strategy and method for grassland management. As grassland resource has spatial and temporal meaning, and forage quality was associated with seasons, optimizing feeding is to keep the balance of the animal growth and time-dependent quality of forage. Important problems in grassland farming in northern China is as follows： 1）Grass performance to gazing and/or cutting, which is basis for understanding grassland healthy existence and/or degradation in grazing reaction. 2）Dynamics of net grassland production and nutritional process of forage, which is central factors for determining grazing feeding. 3） Rational grazing, i. e. , adaptive intensity and frequency of grazing, which is ensuring for grassland management and for animal production. 4）Optimizing feeding on grassland, which is an active action for grassland management and for animal production.