21 billion chickens are being farmed at any point in time (the number of chickens dwarfs the number of other livestock animals).
The country with the most poultry birds is China (6b), followed by the U.S. (2b) and EU (1.5b). China’s farming of poultry birds has grown dramatically in recent decades as it’s gotten richer.
In the U.S., chickens suffer a number of severe problems, such as overcrowding and disorders related to having been bred for rapid growth.
Protections for farm animals differ across countries; China’s are even weaker than the U.S., while Europe’s are stronger. But things don’t seem great even in countries with the strongest protections, like the U.K.
Animal welfare campaigns have achieved some significant wins in the past decade.
But the number of self-identified vegetarians in the U.S. is only about 5%, and this number has not grown in the last twenty years.
Stats/economics: Our World in Data, Norwood and Lusk 2011
Interventions: Lewis Bollard interview, Animal Charity Evaluators
Donate: Animal Welfare Fund