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 pickup 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 acorn-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.