For cervid, protein requirement during antler growth is up to 15%. Thus, the requirement of specific amino acids for protein synthesis is also very important. Lysine (Lys) and Methionine (Met) are the two known limiting amino acids for ruminants. And for deer, Lys is very interesting for antler growth, since it is the precursor for collagen production. However, very limiting studies conducting on its effects on antlers. In this study, we show the first trial on a large herd of fallow deer (Dama dama) with two experimental designs. Each experiment involved 45 yearling fallow bucks, distributed in three groups based on average weight. The group compositions included Exp. 1: Pasture, Pasture+Barley (0.2 kg/animal per day), and Pasture+Barley+Lys (5 g/animal per day); Exp.2: Pasture+Barley (0.5 kg/animal per day), Pasture+Barley+Lys (9 g/animal per day), and Pasture+Barley+Lys+Met (9 and 3 g/animal per day, respectively). At the first glance, Lys supplementation in the first experiment did not improve any antlers characteristics. However, when the level was increased to 9 g and with the combination of Met in the second experiment, the treatments had good effects on external antler characteristics and antler weight. A very interesting result is the increase in burr perimeter, which is a crucial base for the better and long-term antler growth. The results also suggest a more intense positive effect of amino acid supplementation in situations when the animals have a lower performance. This result opens opportunity for improving deer farming practices, particularly for velvet production and trophies.