The raw materials e.g. carcasses are first rendered. This is the process of processing raw animal material on an industrial scale to remove moisture and fat (note: some rendering plants produce a meat slurry rather than a dry product). Some rendering plants are linked to a particular kind of slaughterhouse; e.g. those near poultry processing plants may deal exclusively with poultry by-products, some specialize in fish products. In the USA, independent renderers process raw material from small packing houses, supermarkets, etc; packer renderers process raw material from only the species they are slaughtering, poultry processors process poultry by-products while protein blenders purchase and dry rendered tankage from the preceding processors as a the raw material for their own process.

The raw product is blended in order to maintain a certain ratio between the contents e.g. animal carcasses and supermarket rejects. The carcasses are loaded into a stainless-steel pit or hopper and an auger-grinder at the bottom grinds up the ingredients into small pieces. It is a larger version of the old table-clamped meat grinder used in the days before food processors. The pieces are taken to another grinder for fine shredding. The shredded material is cooked at 280 Fahrenheit for 60 minutes (US figures, those in Britain and Europe may differ but, remember this temp and time). Meat melts off of bones to produce a soup or slurry. Yellow greasy fat or tallow rises to the top and is skimmed off. Some pet food manufacturers use this slurry. Otherwise, the cooked meat and bone go to a press, which squeezes out the remaining moisture and pulverises the product into a gritty powder. The grit is sifted to remove excess hair and large bone chips. The end products are yellow grease, meat and bone meal..

The term "meal" on a pet food label means that the materials in the meal have been rendered. The quality and content of the meal may be variable across batches. In the USA, this means that some some question the nutritional value of the by-products. James Morris and Quinton Rogers, two professors with the Department of Molecular Biosciences, University of California at Davis Veterinary School of Medicine, felt there was a lack of information on the bioavailability of nutrients of pet food ingredients. The pet food labels give the supposed nutritional adequacy, but the nutrients are no good if they are in a form indigestible by the pet.

Okay, now to the effects of heat. If you burn your finger, what happens? The skin tissue dies. Overly apply heat to food and the nutrients are progressively killed/destroyed.

In my opinion, it is no coincidence that since 1950, as processed food proliferated for both humans and pets, that cancer rates in the United States have steadily increased and are now at the highest point in history (for pets as well as humans). The effect from consuming overly cooked food is minimal nutrition. The body is forced to raid its dwindling supply of nutrient reserves and remains hungry for quality nutrients after a typical meal This leads to further hunger even though the stomach is full. The result can be chronic overeating and rampant obesity now seen in our dogs as well as ourselves nationwide.

Scientific Research shows what Denaturation/Cooking Does to Protein:

Cooking denatures protein. According to Encyclopedia Britannica, denaturation is a modification of the molecular structure of protein by heat or by an acid, an alkali, or ultraviolet radiation that destroys or diminishes its original properties and biological activity.

Denaturation alters protein and makes it unusable or less usable. According to Britannica, protein molecules are readily altered by heat:. Unlike simple organic molecules, the physical and chemical properties of protein are markedly altered when the substance is just boiled in water. Further: All of the agents able to cause denaturat-ion are able to break the secondary bonds that hold the chains in place. Once these weak bonds are broken, the molecule falls into a disorganized tangle devoid of biological function.

Again, according to Britannica the most significant effect of protein denaturation is the loss of the its biological function. For example, enzymes lose their catalytic powers and hemoglobin loses its capacity to carry oxygen. The changes that accompany denaturation have been shown to result from destruction of the specific pattern in which the amino acid chains are folded in the native protein. In Britannica is the acknowledgement that "cooking destroys protein to make it practically useless"

There are two ways to denature the proteins: chemically using digestive enzymes, or through the use of heat. Via heat, the body does not have the recombinant ability to utilize damaged denatured protein components (amino acids) and rebuild them once again into viable protein molecules.

Some Physiologists claim that cooking and digestion are virtually the same: that cooking is a form of predigestion where heat is used to hydrolyze nutrients that would otherwise be hydrolyzed at body temperature through digestion. This due to the enormous heat exposure during cooking, that denatures the protein molecule past a point of being bioactive, however, body heat is too low to effect the protein molecule so adversely.

When proteins are subjected to high heat during cooking, enzyme resistant linkages are formed between the amino acid chains. The body cannot separate these amino acids. What the body cannot use, it must eliminate. Cooked proteins become a source of toxicity: dead organic waste material acted upon and elaborated by bacterial flora.

When wholesome protein foods are eaten raw, the body makes maximum use of all amino acids without the accompanying toxins of cooked food.

According to the textbook Nutritional Value of Food Processing, 3rd Edition, (by Karmas, Harris, published by Van Nostrand Reinhold) which is written for food chemists in the industrial processed food industry: changes that occur during processing either result in nutrient loss or destruction. Heat processing has a detrimental effect on nutrients since thermal degradation of nutrients can and does occur. Reduction in nutrient content depends on the severity of the thermal processing.

Protein molecules under ideal eating and digestive conditions are broken down into amino acids by gastric enzymes. Every protein molecule in the body is synthesized from these amino acids. Protein you consume IS NOT used as protein: it is first recycled or broken down into its constituent amino acids AND THEN used to build protein molecules the body needs.

There are 23 different amino acids. These link together in different combinations in extremely long chains to create protein molecules, like individual rail cars form a train. The amino group gives each amino acid its specific identifying characteristic that differentiates it from the others. Excessive heat sloughs off or decapitates the amino group. Without this amino group, the amino acid is rendered useless and is toxic.

Cooked vs. Raw Food and Pottenger’s Cats

Dr. Francis M. Pottenger Jr. MD wrote about his experiments with 900 cats over a period of ten years. Pottenger fed raw meat to a portion of his test cats, and fed cooked meat to the other test cats. Pottenger wrote, Cooked meat fed cats were irritable. The females were dangerous to handle, occasionally biting the keeper.

Cooked meat and a pasteurized milk diet led to progressive degeneration of the animals. He compared healthy cats on raw foods with those on heated diets with mention of parallel findings among humans in Dr. Weston A. Price’s worldwide studies. Behavioral characteristics, arthritis, sterility, skeletal deformities and allergies are some of the problems that were associated with the consumption of all-cooked foods.

The cooked meat fed cats suffered with pneumonia, empyema, diarrhea, osteomyelitis, cardiac lesions, hyperopia and myopia (eye diseases), thyroid diseases, nephritis, orchitis, oophoritis (ovarian inflammation) and many other degenerative diseases. No cooked food is benign. Cooked foods act malignantly by exhausting energy, inhibiting healing, and decreasing alertness, efficiency and productivity.

Dr. Kouchakoff of Switzerland conducted over 300 detailed experiments, which pinpointed the pathogenic nature of cooked and processed foods. Food heated to temperatures of just 120 to 190 degrees F (a range usually relegated to warming rather than cooking which, nevertheless destroys all enzymes), causes leukocytosis in the body. Leukocytosis is a term applied to an abnormally high white corpuscle count.

Without getting into this too much, lets get back to our protien source. How healthy is the chicken or turkey or "meat meal" being rendered and going into your pet's food in the first place?

In some countries, road kill which is too large to be buried along the roadside is sent for rendering. This is an efficient method of disposal. Condemned material from slaughterhouses goes for rendering: animals that died in transit, diseased animals or animal parts, blood, hair, feet, head and any part of the animal unsuitable for human consumption.

In Canada, the denaturing chemical is Birkolene B and its composition remains secret. In the U.S. carbolic acid (potentially corrosive disinfectan, toxic), creosote (used for wood-preservation or as a disinfectant, toxic), fuel oil, kerosene and citronella (an insect repellent made from lemon grass) may be used. In other countries, the meat is simply dyed e.g. blue or green using a non-toxic dye.

James Morris, a professor at the School of Veterinary Medicine at Davis, California, stated that any products not fit for human consumption were very well sterilised so that nothing can be transmitted to the animal. Many believe this to be a naïve statement especially after the British BSE situation. In the UK, cattle feed was believed to be well sterilized until BSE emerged; the causal agent was not destroyed at the sterilizing temperature. The size of the rendering batches greatly dilute any drugs or chemical substances which may be present in the source animals.

The pet food market benefits pet owners (convenience, ready-made balanced diet) and also benefits human food industries and animal farmers by providing a market for by-products. It is not a new trade. In Britain half a century ago, ill or old livestock ended up at the knackers (small scale slaughterhouse) and often ended up being fed to hounds or farm dogs. Many towns had a "cat's meat man" who sold skewers of waste meat to cat owners for a couple of pennies.

A current concern to owners is the use of cloned and GM animals. Cloning animals is currently too expensive to be practical for food production, but farmers could clone top-quality animals as breeding stock. Food products and by-products from the offspring of clones and from clones themselves will be indistinguishable from that from normally conceived animals and, in the US at least (where the powerful food producers' lobby groups render food safety groups largely impotent), will not need special labelling as to its origin.

In the USA, food animals are routinely dosed with antibiotics, anabolic steroids and growth promoting hormones prohibited in Europe. The residue of these chemicals enters the food chain and can cause allergic reactions (and probably less obvious effects) in humans and pets. In Britain, pigs were once routinely dosed with penicillin and the drug residue ended up in pork products; my uncle, who was allergic to penicillin, suffered allergic reactions to sausages made from pigs medicated with penicillin. Similar allergic reactions might be overlooked in pets. The antibiotics are used because animals reared in intensive conditions suffer disease through over-crowding and from wading through their own waste products (the latter results in the higher incidence of harmful E coli strains). As a result of widespread antibiotic use, antibiotics are now present in low levels in the environment and resulting in ever-stronger bacteria - the so-called super-bugs - through mutation and natural selection.

Supporters of organic petfoods suggest that many of the digestive problems, skin conditions and even behavioural problems in pets could be due to chemical residues in their food. Within the European Union, pet owners should be cautious of imported petfoods and of petfoods made with meat products sourced from countries where growth promoters and antibiotics are routinely used . In general, European Union countries place far more emphasis on testing food animals and slaughterhouses for pathogens (e.g. E coli, salmonella, BSE) while American food producers resist the routine testing of animals and processing plants for these pathogens. As a result, many European pet foods may actually be safer (i.e. the meat more stringently tested and controlled) than American fast foods!

Prof. Dr. Sir John Whitman Ray B.A., ND., D.Sc., NMD., CT. MT.. CI, Cert. Pers., PhD., B.C Dip N, MD. (M.A.), Dr. Ac, FFIM., Dp. IM., F.WA I .M., RM., B.E.I.N.Z., S.N.T.R., N Z. Char. NMP, N P A

Dr. Francis M. Pottenger Jr. MD

Dr. Kouchakoff of Switzerland

Dr. Weston A. Price’s

Note: An excellent factual text about food production methods in the USA is "Fast Food Nation" by Eric Schlosser. "The Food Scandal" by Caroline Walker and "The Meat Machine" by Jan Walsh look at food processing methods in the UK (the latter two books are now only available second hand). Although the books were written about the human food chain, pet foods contain by-products from the the animals raised to feed humans.

So back to the process of making the pet food:

The raw materials e.g. chicken, lamb or cattle carcasses, are rendered. The pet food manufacturers buy either the meat slurry or the dried meal produced by the rendering plants. Canned, dry or semi-moist pet foods all contain similar ingredients. The ratio of protein, fat and fiber may be different and the amount of water present and the types of preservative used will differ greatly. Canned food is more bulky which is good for bowel action, but its soft texture means that teeth are not "exercised" which leads to tartar build-up and gum disease.

Dry food is then made with a machine called an expander or extruder. The raw materials are blended and the mixture is fed into an expander. It is then pressure cooked (steam, pressure, very high temperature) into a paste which is extruded through pipes which shapes blobs of paste into small biscuits or uniform shapes. These are then puffed like popcorn and baked or dried, then sprayed with fat, digests, vitamins and flavour enhancers.

The cooking process kills bacteria, but may be ineffective against heat stable toxins or prions (causative agents in BSE). Non-extruded dry foods are baked and are denser and crunchier and may require no coating of fats of flavourings, just vitamins and minerals, etc that were killed in the baking process.

Most canned foods, especially budget varieties, are meat slurry which may or may not have been texturized and which contains a gelling agent to solidify them. A typical can of pet food may contain 45-50% meat or poultry by-products. Some contain more water than others - those in jelly or gravy containing the greatest amount of water. In order to compare different cans, the water has to be removed and an analysis performed on the remaining dry matter. Some labels provide a "dry matter analysis" to aid the comparison. To make canned food, the ground ingredients are mixed with additives. The meaty chunks are made using an extruder. The mixture is cooked and canned. The sealed cans are sterilized by pressure cooking. Some food is cooked in the can instead of beforehand.

Cooking, rendering, drying, canning and baking all destroy vitamins, amino acids and enzymes. The by-products used as raw ingredients are poorer quality and contain less nutritional value than the prime cuts of meat depicted on the label. Pet food manufacturers therefore fortify the product with vitamins and minerals after the cooking process.

I am often berated for recommending a raw diet as being best for our pets but after all my research and feeding my own pets this way for years now, I can not help but believe that our pets would be much healthier in the long run if fed live whole foods.

Note: Before switching your pet to a raw or an alternative diet , please seek the advice of your holistic veterinarian or a pet care consultant that can help you make sure it is properly balanced and healthy for your individual pet.

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Jeannie
Natural Pet Care Consultant