A little about why grass fed is important, straight from La Cense's website:
Grass is the natural food for cattle – not grain, which is difficult for cattle to digest and can necessitate the use of antibiotics. The introduction of even a little grain into the cattle's diet diminishes the quality of the beef, reducing both health benefits and the real beef flavor. Most beef in most supermarkets and butchers comes from gigantic industrialized meat processors, who are more concerned with their bottom line than with raising healthy cattle in humane ways. They pack cattle into feedlots where the animals are fed grain laced with antibiotics, hormones and steroids so that they grow bigger faster and can withstand the cramped, inhumane environment. Even some so-called "grass-fed" brands can be "finished" on grain to produce rapid weight gain before market.
La Cense Black Angus cattle are born, raised, and finished on our Montana ranch, where they graze rotationally in open pastures on the tips of tall grass. Strangely enough, this sustainable approach is somewhat revolutionary nowadays, but it's the way cattle were raised for centuries and the way they're still raised in places like Argentina, which is known for its exceptional beef.