Raw Meat can be obtained by killing wild livestock (the larger cows yield 4, where as the smaller sheep only yield 2). You must cook it afterwards in order to make it edible using matches and a fireplace.
Cooked meat restores all of your hunger and thirty percent of your health. This is equivalent to the MRE's stats but MRE's do not have to cook. However, meat is more common unlike the MRE requiring to find in military tents.