No U.S. state or federal regulations prohibit the practice of caponizing cockerels—castrating male chickens under one year of age. Crude instructions and surgical implements are readily available to provide any amateur “hobbyist” with the means to perform this procedure, typically on fully conscious, unanesthetized birds. Caponizing has been banned in the United Kingdom due to animal welfare concerns and should be disallowed in the United States.
The Humane Society of the United States, "Welfare Issues with Caponizing Chickens" (2008). HSUS REPORTS. 10.