I recommend a variety of protein sources in the diet for dogs. That includes beef, turkey, pork, lamb, venison, elk and fish and other animal protein sources. The reasoning for this, is to make sure the dog gets a variety of amino acid sources and to stop possible allergies. While food allergies in dogs is rare, dogs can be susceptible if fed the same one or two protein sources daily. It is the over exposure to one protein that can result in allergic reactions after time, usually after the age 2. See Protein and Variety in the Diet here.

A lot of people suggest that if a dog gets itchy, acquires diarrhea, vomiting or tummy rumbling, that they are suffering from consuming a particular type of meat. But that is not true. Dogs CAN react to fatty meats, too much food or too much fiber. Those can result in diarrhea and vomiting. But most of the time, itchy dogs have yeast. That occurs on the face, stomach, the rear end, base of the tail and feet. Here are some easy and economical ways to get rid of yeast on your dog. See Yeast is Most Likely the Culprit if Your Dog is Itching.

Some express that their dogs itch when given chicken. But I am betting it is whatever that company uses to process the chicken or feeding chicken with skin. Skin holds most of the fat and can cause discomfort and itching in some dogs. I always recommending removing the skin from chicken before feeding and rinsing well.

Some state that pork is not good for dogs. That is not true. Pork is an excellent choice. And now we get down to the "meat of the matter". All types of animal protein are equal in digestibility. No one meat is harder to digest than others. Things that can result in stomach problems are as I outlined above. Those are:

1. Fatty meats. Fat in excess amounts can cause diarrhea and on occasion vomit.
2. Mixing carbohydrates (fruit, grains, starches and vegetables in amounts more than 25% of the diet can cause bloating, gas and diarrhea in dogs.
3. Too much food can cause diarrhea ad stomach upset. Average amount to feed dogs is 2% to 3% of their body weight daily.

Research has been done specifically on dogs to test the digestibility of various proteins. The study concluded they were all about equal in dog's ability to digest them well. For more on that, here is the link to the article:

Protein digestibility evaluations of meat and fish substrates using laboratory, avian, and ileally cannulated dog assays

The main reason for stomach issues in dogs is not what type of meat was fed. It is more the fat content of the meal (too much fat content, which is harder on dogs new to raw a raw diet, and is sometimes harder on senior dogs), too much carbohydrate fiber in the diet or simply too much food.

For more information on proteins, fats, carbs and how to make and prepare balanced meals for your dogs, it is important to read my book: Raw and Natural Nutrition for Dogs.