Modern broiler chickens have been bred for rapid growth that causes serious health and welfare problems.
The genetic modification of chickens for extreme rapid growth has created a welfare crisis embedded in the biology of the birds themselves. Broilers grow so fast that their cardiovascular and skeletal systems cannot keep pace, causing painful conditions including ascites (fluid accumulation), tibial dyschondroplasia, and chronic lameness. Slower-growing breeds, while more costly to produce, have dramatically better welfare outcomes and are increasingly required by major food retailers.