Friday, November 14, 2008

Canine Protein Requirements Part 3: Evaluating Protein sources

From previous parts of this little series on protein we remember that a protein molecule is made up of chains of amino acids. Different sources of protein contain different combinations of the 22 or so amino acids. Of these amino acids, 10 are considered “essential” amino acids. “Essential” in this case means that animals cannot produce these amino acids on their own, they must be a nutrient in the diet. During the digestive process proteins are broken down into their individual amino acids. These in turn are then reassembled into the building blocks of body tissues such as skin, hair, muscles, and organs. Amino acids are also utilized to produce metabolic enzymes. Enzymes are necessary for many bodily functions including the regulation of antibodies within the immune system and the transfer of nerve impulses.The most complete and most easily digested and assimilated amino acids for cats and dogs are found in protein deriving from animal sources. Besides being more bio available and containing a wider array of amino acids, both essential and non essential, these proteins are also more palatable. The biological value of a protein is determined by how readily the amino acids broken down and used by the body. For dogs and cats, egg whites are at the top of the list with a biological value of 100, followed by muscle meat like beef, chicken or lamb at 92, and organ meats at 90. Wheat and corn are populating the bottom of the list with biological values of 60 and 54. Cooking meat at the high temperatures as it is required for canned foods and dry kibble reduces it’s biological value. This is one of the main reasons why raw or less processed foods in animal’s diet such as freeze dried or dehydrated meals are top food alternatives.When evaluating the protein source on a bag of kibble, we need to keep in mind that whole meats, such as an ingredient listed as “chicken” or “beef,” contain 75% water. If a whole meat is listed first, the next ingredient should be a specific meat meal to insure the protein in the food is from animal sources, not grains. These are for example chicken meal or beef meal, but never generic “meat meal” or by-product meals. A high quality pet food is made with USDA or human grade sources for meat meals. If the ingredient lists “chicken” first followed by grains or grain by-products, it is an indication that much of the protein in the food comes from the grains and is less bio available. Trying to force carnivores to derive their amino acid requirements from grain sources is one of the main contributors to pet obesity. Remember, our companion animals being carnivores means they are mainly meat and not plant based protein eaters.
What are the best protein sources? Is chicken the best protein for cats? And is beef best for dogs, or is lamb better? There are strong opinions among pet enthusiasts about the answers to these questions. The real answer is that it completely depends on the individual animal. Some research suggests that dogs do better on a diet and protein source that most closely matches that of their ancestors: the food that was available in the region in which the breed developed. Border Collies would eat lamb, fish and poultry as they originated in Scotland where these were staples in the diet. The Greyhound, originating in Egypt, would eat rabbit, pork, poultry and goat. German Shepherds would be fed beef, as they were originally bred in the Alsatian Region of Germany.Breed specific guidelines may be helpful for some dogs. However, for many dogs their heritage is pretty much unknown. For another large group of dogs and cats, food allergies will determine which protein sources are best. Cats are assumed to have all developed on a similar diet of rodents, specifically mice, birds and the occasional rabbit. But to answer the question which meat is best: In the absence of food sensitivities or allergies, I suggest the answer should be “at least three different ones.” Putting your pet on a rotation diet insures a broader nutritional base over time and helps reduce the incidence of food sensitivities and allergies. Many dogs and cats fed the same food for years on end will develop signs of intolerance such as itchy skin or paws, or chronic digestive problems such as gas, loose stools or frequent vomiting. Rotating between at least three or four different foods with different protein sources, and preferably from a variety of manufactures, provides the ideal answer to “Which food is the best for my companion.” Only you and your companion can really and have to determine what is best by trying various high quality foods and choosing those that your dog or cat thrives on.With the growing popularity of grain free and low carbohydrate foods in recent years I find that many pet owners are concerned about feeding not enough or too much protein. One reason for this question is the lingering myth that too much protein in the diet can cause kidney disease, especially in older animals. In the upcoming follow up articles on this topic I will address this issue further. For now let’s just say that nutritional research has shown this is not true. However, as usual, the myth continues to live on. It originated when veterinarians began to put animals with kidney disease on low protein diets to minimize nitrogen levels. Today, holistic veterinarians, and increasingly even traditional veterinarians, are suggesting a diet for animals with kidney disease containing higher quality protein that is more digestible rather than low protein foods. The better quality the protein, the less waste produced through digestion creating less work for the kidneys and lower nitrogen levels in the body.Excess protein in a healthy animal’s diet would typically be either excreted in the urine, used as energy, or converted to fat. An important precaution when feeding a higher protein food is watching how much you feed so as not to allow your pet to gain weight. The answer to “How much protein is too much?” is dependent on the individual animal, it’s metabolism, activity level and lifestyle. If a cat spends most of the day napping and watching its surrounding world without too much of moving around, feed her less of the same food you would feed her if she would be extremely active. Both ways she can thrive on a high quality, high protein diet, the different activity levels are accommodated with different volume of food.Growing puppies and kittens as well as pregnant or nursing mothers and working animals require more protein than normal adult animals. Most of the premium pet foods provide adequate fat and protein levels for their needs provided they are fed larger portions for their size. Adding fresh meat or grain free canned foods to some meals is a great way to provide extra protein.

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