Thanks for the info - most enlightening, although a large part of me simply wants to say, "no surprise!"
My Dad used to work in an abattoir (on the finance side, not shooting cows in the head). Every part, absolutely every part of the animals are used, there isn't a part that isn't sold to someone.
When every remotely decent sellable scrap of lamb sheep was removed and sold, what was left was removed by various means from the carcass and sold to a couple of blokes who made the elephant legs.
It was an Irish company that owned the plant, and it sounded a bit mental. He says that the Irish meat industry was just about cheap - all "crooks, thieves and liars" apparently - they would get orders from supermarkets, then set about trying to produce it to the absolute minimum quality, doing whatever dodgy tricks they could come up with to bring the cost down.