Its report, World Livestock 2011, identifies rising populations and income as fuelling greater consumption of animal protein in developing countries.

Much of the future demand for livestock production will be focused on the world's burgeoning cities, where population growth is the highest. The FAO predicted that demand would be supplied by large-scale, intensive animal-rearing operations.

No viable alternatives

“As it stands, there are no technically or economically viable alternatives to intensive production for providing the bulk of the livestock food supply for growing cities,” according to the report.

But intensive farming could cause groundwater pollution and greenhouse gas emissions, as well as their potential to act as incubators of diseases, warned the report. “An urgent challenge is to make intensive production more environmentally benign,” it concluded

Since 1967, global production of poultry meat increased by about 700%. Egg production soared by 350%, pig meat by 290%, and sheep and goat meat by 200%. Beef and buffalo meat consumption has risen by 180% and milk by 180%.