Amino acid supplementation and immunocastration are two husbandry practices with an increasing interest in the worldwide growing industry of deer farming. Amino acids (AAs) optimise nutrition and feed costs and improve the quality of products such as venison, velvet or antlers. Immunocastration (IC) reduces agonistic behaviours, which produce carcass damage and reduced growth. Thus, both treatments have positive effects on body growth, but may interfere with hormonal regulation, subsequently affecting antler growth. This study aimed to evaluate the combined use of both practices and their impact on body and antler growth. The results suggest a reduction but not total suppression of testosterone, with almost negligible effects on body growth and internal bones, thus not raising animal welfare issues.