While specific cuts have specific flavor profiles, there are a few other factors that influence the flavor of beef. They include cattle breed and age, the amount of exercise the animal gets, slaughter and storage conditions, and aging. And then there's diet. The vast majority of cattle raised for beef in the United States is grain-fed, but there's a growing demand for grass-fed beef. National retail sales jumped from $12 million in 2012 to $272 million in 2016, and more and more supermarkets, farmer's markets, and community-supported agricultural programs, as well as producers selling direct to consumers, are offering grass-fed options. We answer common questions about grass- and grain-fed beef to help you decide which is best for you.