Animal and Poultry Fat
You may have noticed a unique, pungent
odor when you open a new bag of pet food -- what is the source of that delightful smell? It is most often rendered animal
fat, restaurant grease, or other oils too rancid or deemed inedible for humans.
Restaurant grease has become a major component
of feed grade animal fat over the last fifteen years. This grease, often held in fifty-gallon drums, may be kept outside for
weeks, exposed to extreme temperatures with no regard for its future use. "Fat blenders" or rendering companies then pick
up this used grease and mix the different types of fat together, stabilize them with powerful antioxidants to retard further
spoilage, and then sell the blended products to pet food companies and other end users.
These fats are sprayed directly onto extruded
kibbles and pellets to make an otherwise bland or distasteful product palatable. The fat also acts as a binding agent to which
manufacturers add other flavor enhancers such as digests. Pet food scientists have discovered that animals love the taste
of these sprayed fats. Manufacturers are masters at getting a dog or a cat to eat something she would normally turn up her
nose at.
Wheat, Soy, Corn, Peanut Hulls, and
Other Vegetable Protein
The amount of grain products used in pet
food has risen over the last decade. Once considered filler by the pet food industry, cereal and grain products now replace
a considerable proportion of the meat that was used in the first commercial pet foods. The availability of nutrients in these
products is dependent upon the digestibility of the grain. The amount and type of carbohydrate in pet food determines the
amount of nutrient value the animal actually gets. Dogs and cats can almost completely absorb carbohydrates from some grains,
such as white rice. Up to 20% of the nutritional value of other grains can escape digestion. The availability of nutrients
for wheat, beans, and oats is poor. The nutrients in potatoes and corn are far less available than those in rice. Some ingredients,
such as peanut hulls, are used for filler or fiber, and have no significant nutritional value.
Two of the top three ingredients in pet
foods, particularly dry foods, are almost always some form of grain products. Pedigree Performance Food for Dogs lists Ground
Corn, Chicken By-Product Meal, and Corn Gluten Meal as its top three ingredients. 9 Lives Crunchy Meals for cats lists Ground
Yellow Corn, Corn Gluten Meal, and Poultry By-Product Meal as its first three ingredients. Since cats are true carnivores
-- they must eat meat to fulfill certain physiological needs -- one may wonder why we are feeding a corn-based product to
them. The answer is that corn is a much cheaper "energy source" than meat.
In 1995, Nature's Recipe pulled thousands
of tons of dog food off the shelf after consumers complained that their dogs were vomiting and losing their appetite. Nature's
Recipe's loss amounted to $20 million. The problem was a fungus that produced vomitoxin (an aflatoxin or "mycotoxin," a toxic
substance produced by mold) contaminating the wheat. In 1999, another fungal toxin triggered the recall of dry dog food made
by Doane Pet Care at one of its plants, including Ol' Roy (Wal-Mart's brand) and 53 other brands. This time, the toxin killed
25 dogs.
Although it caused many dogs to vomit,
stop eating, and have diarrhea, vomitoxin is a milder toxin than most. The more dangerous mycotoxins can cause weight loss,
liver damage, lameness, and even death as in the Doane case. The Nature's Recipe incident prompted the Food and Drug Administration
(FDA) to intervene. Dina Butcher, Agriculture Policy Advisor for North Dakota Governor Ed Schafer, concluded that the discovery
of vomitoxin in Nature's Recipe wasn't much of a threat to the human population because "the grain that would go into pet
food is not a high quality grain."3
Soy is another common ingredient that
is sometimes used as a protein and energy source in pet food. Manufacturers also use it to add bulk so that when an animal
eats a product containing soy he will feel more sated. While soy has been linked to gas in some dogs, other dogs do quite
well with it. Vegetarian dog foods use soy as a protein source.
Additives and Preservatives
Many chemicals are added to commercial
pet foods to improve the taste, stability, characteristics, or appearance of the food. Additives provide no nutritional value.
Additives include emulsifiers to prevent water and fat from separating, antioxidants to prevent fat from turning rancid, and
artificial colors and flavors to make the product more attractive to consumers and more palatable to their companion animals.
Adding chemicals to food originated thousands
of years ago with spices, natural preservatives, and ripening agents. In the last 40 years, however, the number of food additives
has greatly increased.
All commercial pet foods must be preserved
so they stay fresh and appealing to our animal companions. Canning is a preserving process itself, so canned foods contain
less preservatives than dry foods. Some preservatives are added to ingredients or raw materials by the suppliers, and others
may be added by the manufacturer. Because manufacturers need to ensure that dry foods have a long shelf life to remain edible
after shipping and prolonged storage, fats used in pet foods are preserved with either synthetic or "natural" preservatives.
Synthetic preservatives include butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), propyl gallate,
propylene glycol (also used as a less-toxic version of automotive antifreeze), and ethoxyquin. For these antioxidants,
there is little information documenting their toxicity, safety, interactions, or chronic use in pet foods that may be eaten
every day for the life of the animal.
Potentially cancer-causing agents such
as BHA, BHT, and ethoxyquin are permitted at relatively low levels. The use of these chemicals in pet foods has not been thoroughly
studied, and long term build-up of these agents may ultimately be harmful. Due to questionable data in the original study
on its safety, ethoxyquin's manufacturer, Monsanto, was required to perform a new, more rigorous study. This was completed
in 1996. Even though Monsanto found no significant toxicity associated with its own product, in July 1997, the FDA's Center
for Veterinary Medicine requested that manufacturers voluntarily reduce the maximum level for ethoxyquin by half, to 75 parts
per million. While some pet food critics and veterinarians believe that ethoxyquin is a major cause of disease, skin problems,
and infertility in dogs, others claim it is the safest, strongest, most stable preservative available for pet food. Ethoxyquin
is approved for use in human food for preserving spices, such as cayenne and chili powder, at a level of 100 ppm -- but it
would be very difficult to consume as much chili powder every day as a dog would eat dry food. Ethoxyquin has never been tested
for safety in cats.
Some manufacturers have responded to consumer concern, and are now
using "natural" preservatives such as Vitamin C (ascorbate), Vitamin E (mixed tocopherols), and oils of rosemary, clove, or
other spices, to preserve the fats in their products. Other ingredients, however, may be individually preserved. Most fish
meal, and some prepared vitamin-mineral mixtures, contain chemical preservatives. This means that your companion animal may
be eating food containing several types of preservatives. Federal law requires preservatives to be disclosed on the label;
however, pet food companies only recently started to comply with this law.
