What's Really in Pet Food?
Although the purchase price of pet food does not always determine whether a pet food is good or bad, the price is often a good indicator of quality. It would be impossible for a company that sells a generic brand of dog food at $9.95 for a 40-lb. bag to use quality protein and grain in its food. The cost of purchasing quality ingredients would be much higher than the selling price.
The protein used in pet food comes from a variety of sources. When cattle, swine, chickens, lambs, or other animals are slaughtered, the choice cuts such as lean muscle tissue are trimmed away from the carcass for human consumption. However, about 50% of every food-producing animal does not get used in human foods. Whatever remains of the carcass — bones, blood, intestines, lungs, ligaments, and almost all the other parts not generally consumed by humans — is used in pet food, animal feed, and other products. These “other parts” are known as “by-products,” “meat-and-bone-meal,” or similar names on pet food labels.
The Pet Food Institute — the trade association of pet food manufacturers — acknowledges the use of by-products in pet foods as additional income for processors and farmers: “The growth of the pet food industry not only provided pet owners with better foods for their pets, but also created profitable additional markets for American farm products and for the byproducts of the meat packing, poultry, and other food industries which prepare food for human consumption.”
Many of these remnants provide a questionable source of nourishment for our animals. The nutritional quality of meat and poultry by-products, meals, and digests can vary from batch to batch. James Morris and Quinton Rogers, two professors with the Department of Molecular Biosciences, University of California at Davis Veterinary School of Medicine, assert that, “There is virtually no information on the bioavailability of nutrients for companion animals in many of the common dietary ingredients used in pet foods. These ingredients are generally by-products of the meat, poultry and fishing industries, with the potential for a wide variation in nutrient composition. Claims of nutritional adequacy of pet foods based on the current Associationof American Feed Control Officials (AAFCO) nutrient allowances (‘profiles’)do not give assurances of nutritional adequacy and will not until ingredients are analyzed and bioavailability values are incorporated.”
Meat and poultry meals, by-product meals, and meat-and-bone meal are common ingredients in pet foods. The term “meal” means that these materials are not used fresh, but have been rendered. What is rendering? Rendering, as defined by Webster’s Dictionary , is “to process as for industrial use: to render livestock carcasses and to extract oil from fat, blubber, etc., by melting.” Home-made chicken soup, with its thick layer of fat that forms over the top when the soup is cooled, is a sort of mini-rendering process. Rendering separates fat-soluble from water-soluble and solid materials, removes most of the water, and kills bacterial contaminants, but may alter or destroy some of the natural enzymes and proteins found in the raw ingredients. Meat and poultry by-products, while not rendered, vary widely in composition and quality.
What can the feeding of such products do to your companion animal? Some veterinarians claim that feeding slaughterhouse wastes to animals increases their risk of getting cancer and other degenerative diseases. The cooking methods used by pet food manufacturers — such as rendering, extruding (a heat-and-pressure system used to “puff” dry foods into nuggets or kibbles), and baking — do not necessarily destroy the hormones used to fatten livestock or increase milk production, or drugs such as antibiotics or the barbiturates used to euthanize animals.