Poultry raising is classified into intensive or extensive systems. Where movement is restricted and birds are kept close together at elevated temperatures, broilers grow rapidly to market weight. In these intensive rearing conditions chickens (broilers) are ready for slaughter in 8–12 weeks and weigh 1.6–1.8 kg. Ducks or ducklings are ready in 8–12 weeks and weigh 1.7–4 kg. Turkeys are ready in 12–30 weeks and weigh 4.5–15 kg.

Intensive rearing systems are usually constructed on hen houses of 8 × 25m which contain 1000 birds per unit. Each producer has many units and contracts to sell his birds at a given weight on a given day. His day - old chicks, feed supplier, veterinarian, transport of birds to the abattoir etc are all programmed to meet a predefined production schedule. These intensive systems are highly programmable, predictable and cost effective.

The intensive system of poultry production prevents or minimises exposure to natural conditions. The extensive system permits the fullest exposure to natural conditions. Where the flock is allowed a free range, feed inputs are used by the bird for exercise and maintenance of body temperature before meat production. Social interaction and the stresses of everyday life use up food energy. This may be regarded as an inefficient production system.

Where extensive systems are practised, the birds are left to scratch for food. This appears cheaper than intensive systems but slaughter weight/time is much more difficult to predict and the system generally can not be used as a basis of contract between producer and meat packer.

In the developed world it is estimated that in excess of 95% of the worlds poultry flocks are reared under intensive conditions. In the developing world the extensive systems are the most usual practices. While this may be due, in some instances, to a lack of poultry management skills, knowledge, infrastructure, capital etc, it may be a natural reaction to the tropical climate.

Poultry have an internal body temperature between 41.2 and 42.2°C, which is about 2–3°C higher than that of mammals. Chicks have a body temperature about 2–3°C lower than that of an adult bird but the adult temperature is reached within about a week of hatching. The major problem poultry have when exposed to temperature extremes is to maintain efficient functioning of their metabolic processes. The relatively high body temperature maintained by poultry means that they are significantly more vulnerable to extremes of heat. This is because they maintain a body temperature only 3–5°C below the temperature at which protein inactivation starts. In poultry production, birds kept within the range 21–26°C at humidities within the range 50–90% will give the highest levels of food conversion into growth. However, at higher temperatures (about 30°C) humidities within the range 30–70% have been shown to reduce growth rate.

Under intensive rearing conditions poultry can suffer extreme levels of stress due to the environment in which they are reared. The close proximity of birds raised in an intensive system inevitably affects their social organisation. Poultry can suffer damage in various ways including disease, attack by predator, cannibalism and feather packing all of which can lead to a reduction in productivity and income. Under extensive conditions social organisation generally remains well structured and much of the damage and stress associated with intensive rearing is absent.

While there is a strong market demand and a continuing increase in production skills, further expansion of the industry is dependent on continued and improved availability of capital (for infrastructure, marketing and working), poultry feedstuff of the appropriate quality, integration of all systems from egg fertilization to consumption of product, management and business acumen, skilled labour, marketing (in terms of quality, consistency and continuity of product) advice and provision of quality, disease - free chicks.