Pasture fed chickens are the grass fed chicken and not the free-range chickens. The term grass fed is usually used for the cows as their natural diet is mostly grass and other green and leafy things. And similarly chickens also rely on grass, vegetables, bugs, weeds, and etc.
Grass fed chickens are those birds and chickens which are fed on a pasture diet. They usually forage for grass, seeds and a healthy portion of of insects.
Nutritional Value of the grass fed chicken
This type of chicken contains a lesser amount of saturated fat and have a higher of vitamin A content. Grass fed chicken contain the fatty acids in a higher percentage.