Contrary to popular belief, dogs are not carnivores. They are omnivores, animals that eat animal and plant protein. The misconception that dogs are carnivores and eat only animal flesh probably comes from the fact that dogs in the wild feed on their prey - other animals. However, their prey are herbivores who eat only plants. When wild dogs kill and eat their prey (caribou, deer, elk, rabbit, etc.), they rip into and eat the intestinal tract first. The intestinal tract is full of partially digested grasses, leaves and other plants.
In addition, wild dogs routinely consume grasses, berries, roots and other vegetable matter. The gastrointestinal physiology of dogs is fully capable of digesting and absorbing plant protein sources as well as meat protein sources.
Many myths exist surrounding the sources of animal protein and plant protein, such as soy, in dry dog foods. The quality of protein in complete and balanced pet foods depends on the right combination of essential amino acids and the digestibility of the protein. Following are a few explanations as to why certain sources of protein are used in dry dog foods:
Poultry by-product Meal
Poultry by-product meal is a good source of animal protein and other nutrients. For this reason, it is widely used by pet food manufacturers as an ingredient in dry dog food formulas. It is a by-product of chicken or turkey poultry processing (generally) and contains about 55-70 percent protein. When combined with the proper complementary protein sources, it provides a balance of essential amino acids that meet the protein needs of normal, healthy dogs.
Soy protein is nutritionally equivalent or superior to animal protein and provides high levels of most essential amino acids. Neither meat nor soybean meal alone is an ideal protein source, but when fed in combination with a complementary source of essential amino acids, the two can help provide excellent protein nutrition to dogs. Unlike animal sources of protein, soy does not vary widely in amino acid content and availability. Poor quality meat or poultry meals are substantially less digestible than soybean meal.
Cereal grains, such as corn or wheat, are combined with another protein source, such as meat or soy, to help provide a complete balance of amino acids. For example, soybean meal and corn complement each other perfectly because the amino acids deficient in one are present in the other. In addition, manufacturers add corn, wheat, barley and other cereal grains to provide a source of carbohydrates that are used for energy. This is why meat and cereal grain ingredients, such as those in Purina O.N.E.® brand Lamb & Rice Formulas or Pro Plan® brand Chicken & Rice dog food formulas, include both ingredients.
Most commercial dog foods have the proper amounts of protein, whether the source is plant, animal or both. While protein needs change throughout a dog's life, any excess protein a dog may take in during a stage of life will not hurt the dog. Some excess may be beneficial in older dogs by helping dogs maximize their protein reserves. Additional protein can be used for energy. All Purina® brand pet foods have adequate protein for their intended life stages.
Feed your dogs balanced and nutritionally complete diets to ensure that the correct levels of protein are present. For more information on protein or other nutritional concerns, call the Purina Pro Club at 1-800-851-3148 and ask for pamphlet PR09 to receive a free copy of the Purina Information Series issue on nutrients.