In the United States and many other countries, standard procedures on farms are specifically exempted from all humane legislation, regardless of the pain and suffering they cause.
Practices such as bodily mutilations, which would warrant felony animal cruelty charges if done to a dog or cat, are perfectly legal when done to a pig or chicken.
At the slaughterhouse, “humane slaughter” laws are weak and poorly enforced for pigs, cattle, and sheep; the slaughter of birds is completely exempt. The CVA supports efforts to improve conditions on farms, but for many reasons, including our desire not to pay others to do things we would not do ourselves, we feel compelled to be vegetarians.
Read more at Animal Issues