If the testes "grew back" the caponizer didn't do a proper job. Testicular tissue was left inside the body cavity. Just a small piece can re-implant an produce testosterone again. If the testicles are removed COMPLETELY INTACT they cannot "re-grow."I run a farm sanctuary and have explored this with roosters rescued from cock fighting and here is what I have learned. The surgery can be risky but if performed by an avian vet can have a reasonable chance of survival. That said- it doesn’t work. One of the largest national farm sanctuaries did autopsies on 10 roosters who were canonized and had died. In 8 of the 10 their testes grew back. They no longer do the procedure. I hope you find this helpful.