This is by far the best gatherer of organic polymer. Carry the moschops to a frozen island with penguins. Put it on follow. Create a whisle group and whisle with the (Xbox) Lb down d-pad while looking at a corpse. It will collect the penguin corpse. Do not do this whisle in your base.
These things are freakin cowards. They will run at the first sign of danger. Make sure to carry with argy while using for maximum efficiency. If you trained it for gathering prime, put it in a tame order group of your choice, and whistle attack target on the dead creature while carrying it with argy/quetz, preferably a quetz because you can carry and attack at the same time, and fly close. Then once it harvests, fly home and enjoy the prime!
From what others have said they do eat random food and so far the list consists of, rare flower, rare mushroom, raw prime fish meat, raw prime meat , Sap , leech blood, and organic polymer. Make sure to have a decent amount of each one of these before starting the tame.
DO NOT PUT POINTS INTO MELEE DAMAGE
POINTS put into melee damage do not increase this creatures gathering efficiency. Speaking as someone who has messed up this way (23 times (have a nice little army going)) a much more useful investment is weight, maybe accompanied by some health.
Get a collar, bring it out to a very densely grown part of the woods and let them wander. This is a great way to collect berries, fiber even wood and thatch. Gather a work force of them and you can level a forest.