However, the proportion of animals raised in intensive production systems is extremely variable
between countries, depending largely on their levels of economic development, and this
represents an important distinction to make in order to understand the impacts and benefits of
livestock production.
In high-income countries, the overwhelming majority of chicken and pig production is
intensive, taking advantage of the high levels of inputs to optimize feed conversion ratios. Only
a small proportion of chickens and pigs is raised under extensive production systems and,
while demand for organic farming products is increasing faster than the average growth of the
agricultural sector, it still remains low in absolute terms [7]. This leads to the paradox that
countries like Belgium and the Netherlands have some of the highest densities of chickens and
pigs per km2 in the world, yet these are hardly seen in the landscape as they are hidden away in
intensive production units. The situation differs greatly in low-income countries, where the
vast majority of chickens and pigs is raised under extensive conditions by family-based smallholder
farms. In transition economies, extensive backyard production co-exists with intensive
farming, to the extent that a very clear bimodal distribution of flock or herd size per holder can
be observed, as for example in Thailand