Extra Omega-3s. Meat from grass-fed animals has two to four times more omega-3 fatty acids than meat from grain- fed animals. Omega-3s are called "good fats" because they play a vital role in every cell and system in your body. For example, of all the fats, they are the most heart-friendly. People who have ample amounts of omega-3s in their diet are less likely to have high blood pressure or an irregular heartbeat. Remarkably, they are 50 percent less likely to suffer a heart attack.[3] Omega-3s are essential for your brain as well. People with a diet rich in omega-3s are less likely to suffer from depression, schizophrenia, attention deficit disorder (hyperactivity), or Alzheimer's disease.[4]

Source: http://www.eatwild.com/healthbenefits.htm