What Sort of Pet Food “Research” Are We Talking About?


Pet food companies that are the size of Hill’s Pet Nutrition (a subsidiary of Colgate-Palmolive Company) and Iams and Eukanuba (both owned by Procter & Gamble Pet Care) can afford to conduct a variety of research and development studies, as well as conduct their own feeding trials to meet regulatory requirements for nutritional adequacy. The following are the types of studies that large pet food companies typically conduct.

What Sort of Pet Food “Research” Are We Talking About?


AAFCO Feeding Trial. The protocols for these tests were developed by the Association of American Feed Control Officials, an advisory (not regulatory) body comprised of state feed control officials (the voting members) as well as representatives from the pet food industry, the Food and Drug Administration (FDA), the United States Department of Agriculture (USDA), and other interested groups and individuals. There are specific protocols for trials that confirm the nutritional adequacy of foods for adult maintenance, gestation/lactation, growth (puppy or kitten food), and “all life stages.” The trials range in duration from 10 weeks (growth) to 26 weeks (adult maintenance). A food intended for “all life stages” needs to pass the gestation/lactation trial (about 13 weeks) followed by the growth trial, back to back.

In all of these trials, a number of dogs are fed the test diet (and nothing but the test diet) and a certain percentage of them must finish the trial in a condition such that they pass some basic tests: not too much weight loss, no significant illness, adequate blood test results (hemoglobin, packed cell volume, serum albumin, and alkaline phosphatase, a liver enzyme). For more information about AAFCO feeding trials, see “On Trial,” WDJ April 2005.

Many people consider AAFCO feeding trials as the “gold standard” for confirming the nutritional adequacy of a canine or feline diet. However, because the products that met the “feeding trial” test of nutritional adequacy do not have to meet the “nutrient levels” criteria, there is the possibility that these products may contain excessive, deficient, or unbalanced nutrient levels that may contribute to the development of health problems if fed as a sole diet for periods that are in excess of the testing period. An ideal test would encompass both a feeding trial and meeting the AAFCO nutrient profiles, but no such standard currently exists.

AAFCO Metabolizable Energy Protocol (also known as “metabolic study”). In these tests, a dog (or cat) is maintained on a specific diet for a period of 10 days, and the amount of food the animal consumes is precisely recorded. During the final five days, every bit of urine and feces eliminated from the animal is collected, so the amount of energy lost through elimination can be calculated (subtracted from the gross energy consumed) and thus, the total energy in the diet that was utilized by the animal can be determined. It used to be routine that these studies required the test subject to be housed for the final five days in a cage with a slatted floor – uncomfortable for any animal. However, in recent years, alternatives have been developed to help researchers collect urine and feces from an individual in a comfortable environment. For example, with cats, Hill’s fills the cat’s litter box with tiny, unabsorbent plastic beads; urine and feces can be collected from this material with little loss.

Palatability or “taste preference” studies.
Pet food makers know that owners repeatedly buy products that their pets prefer and eat quickly and enthusiastically, so they use a tremendous amount of their resources on these studies – more so for cat food than dog food (cats are notoriously finicky about food flavor, odor, and even the “mouth feel” of kibble). The animals used in these tests are given special training to teach them how to assess their options and make a “real” choice – not just fill up on the food they happened to select first, or always eat from the left-hand bowl. Animals that appear to reliably consider their options and make clear, consistent choices are prized, and may be delegated to a lifelong career in these studies.

Digestibility studies. How well a food is digested, and the resulting quality of a dog’s stool, are of utmost importance to most dog owners – and, of course, to the health and comfort of the dog. Pet food makers are always tweaking their formulations, based on ingredient availability, price, and popularity; they use these studies to ensure the resulting innovations are digestible.

Bioassay studies. These studies are conducted in search of diets that target and improve the function or health of a given body system or ability. Bioassays could include mobility, skin and coat, immunology, GI health, or nutritional requirements based on life-stage or lifestyle. Diets that address certain health conditions, whether “prescription” or over-the-counter, have become increasingly popular with pet owners – and as a result, they are popular with the large pet food companies, too.


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