Bib. p. 398-400

Animal production from grazing may be influenced by many managemental decisions. These may act by modifying the production or composition of the plant biomass, the adjustment of the requirements of the animal complex to the production of the plant complex, and the harvesting of the animal complex. The objectives of the grazing systems will seldom be simple, but shoud invoke long-term stability as well as immediate profitability, or other economic criteria of production. The main determinant of production must be the growth of the plant component of the system which can be influenced by the choice of plant species and the manipulation of soil fertility. In addition, the choice of stocking rate, or the grazing pressure imposed by the animal component of the ecosystems, must profoundly affect the level of production from an area of land. Its effect on profitability or biological and financial stability is complex, but management decisions must depend on evaluation of the biological and social criteria. Management practices such as subdivision, supplementation, and adjustment of animal reproduction may affect both the level and the economy of production, but to a minor extent relative to that of pasture productivity and stocking rate. The components of the production ecosystem interact with each other, and with the management systems which are imposed. For example, fodder conservation may not be feasible at higher stocking rates, at which the need for supplementation may be greater. Pasture resting may be necessary for some species but not for others, to a degree which may depend on the stocking rate, the soil, and the species of grazing animal. Investigation of techniques of grazing management must be designed so that the results are applicable to actual or potential production systems. Extrapolation from the results of finite experiments must be based on an understanding, not only of the component processes in the systems, but also of the way in which these interact to generate a particular level of production. The techniques of systems analysis are therefore likely to aid increasingly in decisions on management of grazing systems