Effect of Western chicken and GH
Poultry raised for meat in the US (called broilers) reach butchering size in 5 to 8 weeks (compared to 10 weeks for half the size 40 years ago. It's not a GH miracle; it's a result of generations of selective breeding (as cows have undergone for unhealthy udder size).

GH use is illegal in the US and many other countries. Honestly, it's an unnecessary additive/expense.

I raised poultry for more than a decade, mostly chickens and ducks (but almost everything else as well). Once I bought 25  1-day-old broiler chicks (early broilers were a Plymouth Rock X Cornish) alongside my usual mix.  Within 2 weeks the broilers were at least 3 or 4 times the size of the other chicks, and more than a couple of them died (under ideal conditions - all free-range outside, cooped only at night). By 10 weeks, they were enormous.

They were also dumber than a bag of hammers, unfortunately. I felt so sorry for them that I let them live out their natural lives, which wasn't terribly long, partly because of their docile stupidity.

Growth hormone is unnecessary in the poultry industry.

Murray McMurray Hatchery: Jumbo Cornish X Rocks
Modern Meat Chicken Industry