Never mind. I forgot that I asked that question. I have figured out, that you can use the "Science-Station" or what ever its called to make a grown up beast. You need to put it into your inventory and after that into your quickbar, to use it (has the same animation as eating bizarrely...). Then it spawns the beast. If you put it into your quickbar direktly from the "Science-Station" you just eat it and it does not spawn.
Edit: I do think that its kinda useless though, since its pretty bugged and runs around weirdly sometimes and might also just die if you fight some other beast since you might hit it as well...