On most pet food labels, there will be a statement indicating that the food is "complete and balanced" for a particular life stage of the pet (there are only two: growth/reproduction and adult).
A pet food may be labeled as "complete and balanced" if it meets AAFCO standards. There are two methods for achieving this: (1) meeting published standards for content, or (2) feeding tests. If a food does not meet either of these standards, it will be labeled "for intermittent and supplemental feeding only." Such foods are fine as treats or for short periods of time, but should not be fed as the sole diet. Keep in mind, too, that the standards, such as they are, set only "minimums" and "maximums," not "optimums." Commercial pet foods are designed to be adequate for the average animal, but may not be suitable for an individual animal's variable needs.
Vitamins And Minerals In Foods
(1) Nutrient Profiles. These standards set the required amounts of protein, fat, vitamins, minerals, and so forth. When adopted in 1989, they were the best information available on canine nutritional needs. New research was published in 2003 that provides up-to-date information, but new standards are still in the process of being adopted by AAFCO and/or the states, and are not currently being followed by pet food manufacturers.
Moreover, any manufacturer can synthesize a food containing sufficient amounts of each ingredient according to the Nutrient Profiles, yet dogs may not do well on it because the standards do not address the issues of "bioavailability" of nutrients to the animal. Certain forms of vitamins and minerals, for example, are poorly absorbed from the digestive tract. A noted veterinary nutrition textbook claims that a food can be created from old leather boots, wood shavings, and crankcase oil that will meet the technical requirements for protein, carbohydrates, and fats, yet would be completely indigestible. Unfortunately, given the ingredients used by some manufacturers, "Old Boot" may be closer to the truth than anyone wants to admit!
(2) Feeding Trials. These are considered the "gold standard" of pet food formulation. However, when you look at the actual AAFCO protocols for an adult maintenance diet, a manufacturer must feed exclusively the test food to only six animals for six months. (Eight animals are required at the outset; however, two of them may be dropped from the trial for non-diet-related reasons.) Foods intended for growth and reproduction must be tested for only 10 weeks.
Most of the large, reputable pet food producers, such as Iams, Hills, Walthams and Purina, maintain large colonies of dogs and cats, and test their foods on hundreds of animals over years or even multiple generations. Other manufacturers rely on facilities that keep animals for this purpose to do the studies for them.
It is easy to see how a poor quality diet could be fed for only six months without seeing adverse health effects, and legitimately be labeled as meeting AAFCO standards. In fact, studies have confirmed that even foods that pass feeding trials may still be utterly inadequate for long-term maintenance.
Worse still is AAFCO's "family rule" which was heavily promoted by the pet food industry. This rule declares that foods that are "nutritionally similar" to a food that has passed an actual feeding test may also carry that claim. The "similarity" need only be that the foods have a similar calorie content. This leaves the "feeding test" label as a completely unreliable indicator of the quality of the food, and its status as a "gold standard" in serious doubt.
Life Stages. As mentioned above, there are only 2 life stages recognized by the AAFCO standards: adult maintenance, and growth/reproduction, which includes puppies and kittens as well as pregnant and lactating (nursing) mothers. Foods claiming adequacy for "All Life Stages" meet the higher nutritional requirements of growth/reproduction.
This means that there are no separate standards, and thus no regulations about, food for "senior" or "mature" pets, foods designed for "Yorkshire Terriers" or "Persian Cats," or foods for "high performance" or "indoor" animals. These designations are purely marketing hype. Yes, the ingredients may be a little different, or the protein or fiber content may have been manipulated, but every single niche food must still meet one of those same two basic requirements. A claim of "light" or "reduced calories" does have to be a certain percentage less calories than the food it is being compared to, but whether such foods actually help pets lose weight in a healthy manner is highly debatable.
In the next article: Natural and Organic pet foods