Sustainable grazing systems

摘要

This paper discusses some of the core issues for the sustainable management of grazing systems for livestock production. Grasslands are widely utilised for livestock production, but various pressures mean that many are now over-utilised, leading to moderate to severe degradation in many parts of the world. To manage grasslands sus-tainably it is important to first understand the biological potential of the system and then develop practices that utilise grasslands at a level that enables the desirable species to survive and to be productive. An analysis of the requirements for higher rates of grassland growth and of animal intake that produces higher rates of animal growth indicates that stocking rates in many regions need to be substantially reduced if the grasslands are to be rehabilitated. These reductions could increase or at least maintain profits, while improving the grasslands. Economic considerations should follow from deciding on the limits of production that can be obtained sustainably from a grassland, rather than the production being expected to meet economic needs. The limits for production from grasslands also need to consider the social and community constraints that often determine the realistic levels of production. A common factor in managing grasslands for the benefits of plants and of the livestock is the herbage mass. For many grasslands it is possible to set minimum levels of herbage mass below which they should not be grazed. This provides a readily used tool for managing grasslands sustainably.