The amount of darts needed to bring one down is too low, at least if you are bringing one down solo. I pumped 600 tranq darts into a lvl 154 a's fast as 5 long neck rifles would allow. Didn't go down. What a waste of time.
I dare you to raise one!! They are savage if you got two high lvl parents (about lvl 140ish) and you get imprinting on it. The thing will become an adult with about 230% melee and basically one chomp any bronto!!! But on the down side you loose your job and your girlfriend
Make 4 metal dino gates and 1 large bear trap. Place three frames and door into an incomplete square and the large bear trap in the I between them. Lure the Giga into the trap and while its trapped place 4th down to make the square. Then just light it up with tranqs