If you uncryo then pick up and throw the ferox at least 2-3 times, it will dig up element dust. If you cryo and repeat the first process it will dig up dust quicker.(you must throw him at least 3 times to make it work)
Don't waste time breeding, it will not get an imprint bonus while in big form and it's stats will reroll. Hopefully the devs fix this soon, it's been months.