Concerning the old cattle - there were a couple places google brought up that said older beef was more flavorful. Of course it needs to be aged properly too. Here's the article from a restaurant in Hong Kong that serves the Galician beef.



They mentioned that it wasn't the most tender beef, but apparently they think the flavor far outweighs the less tender aspect, since they didn't make it sound like it was incredibly tough either, just not as tender as some beef.