From experience we have found that feeding dogs a raw diet actually makes them more calm and content.  In some cases, as your dog’s meal is much higher value to them than their previous diet, you may find that they can become more tense if approached when eating.  This is normal and it is best to give them space to enjoy their meal and so they understand that you are not going to take it off them.  When training, follow the same basic rules when retrieving items off your dog.