I am not the person who posted the above response, but I did give my rooster the hormone implant when he was a little over a year old- mostly because he became aggressive. The vet said he was already full of hormones at this age and had already started with his bad (aggressive) habits, and the implant works best prior to the start of sexual maturity, but we gave it anyway. He was already crowing before the implant, but after the implant he crowed less. His plumage was not affected. His aggression decreased for maybe a month, and he stopped mounting the hens for a few weeks. Within 2 months he was totally back to the way he was before the implant. We waited too long to have great success, so if you can give it early (like maybe 4 months??) hopefully you have better success. Good luck!Do you have an update? We are considering keeping a rooster we hatched but do not want to upset the neighbors. Roosters are allowed though. We would consider it if the rooster still has a protective instinct (to alert the hens of hawks, not physically protect them) and also grows the beautiful plumage roosters are known for. We do not want to breed so sterilization would be ok if it is a side effect. Lastly, did their demeanor stay docile? Thank you for any information you can offer!!