I tamed a level 40 one with 1125 health with just about 30 or so rockarrots and it took only 30 or so minutes. If you have a medium crop plot, alot of space around your part of the island, a crossbow, and about 30 or so tranq arrows, you are perfectly set for taming a big one. Recommend getting all female tames of all animals because they’ll constantly give you free eggs