Globally, poultry are kept under a wide variety of production systems that range from those with very rudimentary night shelters to those with fully automated, environmentally controlled systems. In developing countries, the housing, management and feeding of indigenous poultry stock in rural villages is for the most part basic. Poultry are kept in simple night shelters with very limited management and disease prevention inputs, and minimal supplementary feeding using household scraps and small amounts of grain. Because of natural selection and their capacity for foraging, the birds are able to survive, grow and lay eggs in these environments, and in so doing, make a significant contribution to the food security and protein intake of human populations. However, the normally low productivity of these genotypes means that it is generally not cost-effective to rear them under intensive management systems.

Irrespective of the size of operation, the large majority of commercial production units utilize commercial rather than indigenous genotypes. Commercial production systems with highly selected meat or egg types of poultry require a suitable physical environment, optimal nutrition and efficient protection from the effects of disease. To achieve these, the birds must be at least partially confined, so need to be provided with all or most of their nutritional requirements. Foraging is generally not used except in free-range systems, where only a small proportion of the birds’ nutrient requirements is typically met from the range.

Commercial egg and meat birds have high requirements for protein and energy and do not tolerate high fibre levels in their diets. Poultry diets are thus expensive, particularly if all of the feed ingredients required are imported. Constraints for feeding in developing countries are the very wide variation in the quality and composition of poultry feed, which is often of questionable quality. Because of the high cost associated with the provision of an optimal physical environment, particularly in hot tropical regions, sophisticated environmentally controlled housing is generally only used in large-scale operations.