If he wants to - how can the final consumer when purchasing a quilt ensure that the down and feathers were not harvested from the live animals?

 

He cannot recognize it by the finished product. However, as a rule down and feathers harvested from the live animal are much more expensive (huger personnel expenditures, larger down, huger expenditures as regards logistics) than the material deriving from the animal after slaughtering anyway. This amounts to ca. 98% of the total supply.