May 28, 2007 Genetically selecting for superior produce has been a staple of farming for hundreds of years. The dairy industry is now looking at how it can selectively breed dairy cows to bring their output closer to the way consumers are choosing to use it. In particular, they're having good results identifying cows that can produce tasty low-fat 'skim' milk - which accounts for 75% of milk sold in some countries. What's more, they've also found a cow whose butter is spreadable right out of the fridge. Her name? Marge.