The extreme growth rates achieved by modern commercial broiler chickens create serious respiratory welfare problems, including ascites syndrome and chronic oxygen deficiency, that affect millions of birds annually.
Ascites and respiratory compromise in fast-growing broilers represent a form of chronic suffering that is an inevitable consequence of breeding for extreme growth. Affected birds experience breathlessness, lethargy, and abdominal distension before death — welfare impacts that last days to weeks. The scale is enormous: even at a 2% ascites mortality rate, the global broiler flock of over 70 billion birds annually means over a billion deaths from this single welfare-relevant condition each year. The welfare solution requires transition to slower-growing breeds that develop cardiovascular capacity proportional to body mass. The European chicken commitment and similar initiatives specify slower-growing breed requirements. Consumers, retailers, and producers who commit to these standards drive the market transition necessary to make welfare-relevant breed change economically viable.