Most of us know that dogs need a good source of protein in order to stay healthy and active and live a long, happy life. And yet, when comparing the different dog foods available, it can be hard to figure out which will give your pet the right amount, and more importantly, the right kinds of protein.
The fact is, not all proteins are made equally. Some protein sources are easier for your dog to digest and thus to extract their nutrients. And just because one dog food has a higher protein content than another doesn’t mean it is necessarily the better one for your pet. If your dog food is an AAFCO-approved product, your dog will be getting the minimum amount needed to maintain adequate health, but the digestibility and quality of the protein can still vary.
The Question of Digestibility
Protein provides energy for dogs and is also the source for many essential amino acids, without which a dog cannot thrive. Dogs require 20 amino acids, 10 of which dogs can synthesize themselves and 10 which must come from proteins in the diet.
In order to utilize these amino acids, however, dogs must be able to digest the protein. This is why a high protein content in a dog food is no guarantee of quality. If that protein is difficult to digest, it isn’t going to supply the same benefit that a food with less protein, but of a source that is more digestible, can provide.
The amount of usable amino acids in a protein is called its biological value. Eggs have the highest biological value and are thus the benchmark for this measurement; they are given a value of 100 points. Fish meal comes next, with a value of around 92. Among the various meats, lamb and chicken provide the most digestible forms of protein for your dog, with beef coming in after that.
When looking at a dog food’s ingredients label, a high quality dog food will list these protein sources first—lamb, chicken, beef, and some of the by-products of these animals. Many people may flinch when they see the word “by-product,” but by-products made up of animal organs and blood can actually be a good protein source for dogs. Commercial dog foods won’t use hides, hair, and hooves, which are very hard for a dog to digest.
Grain products such as corn gluten and the legume, soy, are also relatively good sources of digestible protein but often are not as well balanced in necessary amino acids. They can, however, be used to balance amino acid profiles in commercial pet foods. Since dogs are omnivores—eaters of both meat and sometimes plants—there is evidence that the addition of carb-containing grains to a food is healthy for a dog, particularly since all grains except wheat are not high on the allergy list for dogs.
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This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian. It has however been reviewed for accuracy by Dr. Joe, a board certified veterinary nutritionist and graduate of Cornell University's program for Veterinary Medicine.