The Google Instant answer for the question [does butter contain trans fat?] says 100 g butter contains 3.3 g of trans fat.

http://imgur.com/a/i7qw0

Trans fats sometimes occur naturally in food. They're created by bacteria in an animal's stomach.

Trans fats were nothing to do with weight loss. Trans fats were used because they're cheap and have long shelf life.

Yes they do contain trans fats - just not the same kind - and recent research shows that they are probably just as damaging as the artificial creations. See my comment to the other poster.