If you find a low level giga and if you have a friend or two you can build a 4x4 stone box that is 3 walls high (use door frames for shooting it) and a ramp up one side (credits to Tecorsuh on YouTube for the trap idea) you and your friend(s) can use crossbows with tranquilizer arrows to knock it out. I’d recommend each person taking one primitive crossbow with 100 tranquilizer arrows. After the giga is knocked out (do make sure you have plenty of narcotics as the giga’s torpor drops at an alarming rate) just give it raw prime meat or regular raw meat. If you followed this little guide here, enjoy your friend the giga!