Livestock production usually forms an integrated part of complex farming systems. Therefore, sustainable development should take account of the role of livestock in the farming and household systems. In the Netherlands livestock is only kept for the production of meat, milk or eggs. In the tropics it is usually much more diverse and other roles may be much more important. The precise role varies between regions and may be strongly affected by higher level systems of the village or region, and village, regional and government policies. Livestock, therefore, can be seen as a subsystem within a farming and agriculture system.