This is a guide on how to interpret pet food labels in America. The laws are shoddily enforced and pet food manufacturers are more-or-less self-policing (as the 2007 pet food recall and fallout demonstrated), but this page explains the most basic guidelines there are.
Ingredients on the label must be listed in descending order according to weight. Sounds simple enough, but pet food manufacturers can be tricky about this. One popular method of making a food seem as if there’s more meat in it is known as “ingredient splitting.” In short, a dry food ingredient list may read something like “Chicken, corn gluten meal, poultry by-product meal, ground yellow corn, brewer’s rice, chicken fat (preserved with mixed tocopherols)….” You think oooooh, chicken’s the first ingredient, how nice. But notice that corn actually appears twice in the listing, once as corn gluten meal and once as ground yellow corn, and brewer’s rice is right on its heels. By separating plant ingredients of the same species into different components and categories, manufacturers can make them appear lower on the list while still adding substantial amounts to the food.
And not only that, but listing “chicken” at the very top is somewhat deceptive, too. The weight of the ingredient is taken into account before it’s cooked, and since dry food has most of the water removed, and since chicken is about 70% water… at the end of it, there’s really not that much “real chicken” in the food at all; poultry by-product meal is the primary animal protein source in this food, because meat meals have most of their water and fat removed before being added to the extruder, therefore allowing a more accurate gauge of how much actual animal protein is present in the food. The downside to using meat meals is that they tend to be over-processed and over-cooked. At any rate, there’s a good chance that when it comes down to it, the plant ingredients outweight the animal ingredients in this particular example of dry food.
Ingredient names must adhere (more or less) to standard definitions as established by the AAFCO. The AAFCO is the American Association of Feed Control Officials, and no, it’s not a regulatory body, it’s merely an association that comes up with standards and suggestions for regulations to be implemented by regulatory bodies (in the case of pet food, usually the state government).
Manufacturers must list all the ingredients in the food on the label, BUT they only need to list what they add at their manufacturing plant. This is a pretty big loophole, since this means that if they receive a shipment of fish meal that has ethoxyquin already added to it (and ethoxyquin is the preservative of choice for many fish meal providers), they don’t need to include that information on their label.
How to Interpret the Names on Labels
If it says just an ingredient name with no modifiers, e.g. “Tuna for cats” or “Tuna cat food”, that means the ingredient must make up at least 95% of the food on a dry-matter basis (70% if including water).
If an ingredient name is followed by a modifier, e.g. “Beef Platter for cats”, that means the ingredient must make up at least 25% of the food. If there are two ingredients followed by a modifier, e.g. “Beef and Wheat Germ Dinner for Cats,” that means the two ingredients must make up at least 25% of the food, with more beef than wheat germ since it’s mentioned first, and at least 3% of the total of the second named ingredient.
If an ingredient is preceded by “With”, e.g. “Cat Food With Chicken Giblets,” it means the named ingredient must make up at least 3% of the food. It can often easily be confused with the term “Chicken Giblet Cat Food”—but trust me, the “with” makes ALL the difference in the world.
If the ingredient is coupled with “flavor,” e.g. “Turkey Flavored Cat Food,” it means that somewhere down the line the pet food might have brushed up against a real turkey. Maybe. Basically, it just needs to have some kind of flavoring in there that’s turkey-based, enough to be “detectable.” This is pretty rare for cat foods, though, and something you’re much more likely to see in treats or dog foods.
And of course pet food manufacturers can come up with any number of names that don’t indicate the percentage of ingredients. “Mixed Grill” is an example, “Premium Feast” would be another. There is absolutely no requirement in this case for the manufacturers to adhere to any sort of minimum ingredient requirements.
Allowable Ingredient variation
Did you know that pet food labels need to be in close agreement with the listed ingredients only once every six months? As long as “nutrient requirements are met”, there can be pretty significant variation (up to 25%) the rest of the year. (NOTE: I really need to research this more in order to make any sort of intelligent comment about this issue.)
Statements of Nutritional Adequacy
You have probably noticed statements on pet food that say something like “Animal feeding tests using AAFCO procedures substantiate that this food provides complete and balanced nutrition for feline growth and reproduction” and such.
Pet foods can claim that they are formulated to meet AAFCO standards for pet nutrition through three ways: by calculation, by chemical analysis and by feeding trials. Calculation basically means somebody with a nutrient database crunches the numbers for the various ingredients and then compares it with the AAFCO nutrient profiles. Chemical analysis means that… well, it’s pretty clear, right? Dudes with beakers and retorts and test tubes, dissolving shit with solvents and coming up with the numbers that way. Neither of these two methods establish any kind of reliable figure for bioavailability.
The third method, feeding trials, does establish that the food is adequate for meeting nutritional needs. At least, that it doesn’t kill anything dead within six months (ten weeks if it’s a kitten).
Another way food manufacturers can claim nutritional adequacy is by equivalence: if the food is in the same “family” as one of the products that have undergone feeding trials, they can claim that the product “provides complete and balanced nutrition” that is “comparable in nutritional adequacy to a product which has been substantiated using AAFCO feeding tests.”
So what are the feeding trials? Frankly, they’re a bit of a joke. It’s not that hard to pass a feeding trial; history, if nothing else, has shown us how many foods with serious nutritional deficiencies are passed as “complete and balanced.” Small Animal Clinical Nutrition, for example, documents a case study in which several cats came down with severe copper deficiency while eating a commercial food that had passed feeding trials for growth and reproduction. And the 19080s provides the most infamous example of a “complete and balanced diet” actually turning out to be dangerously lacking in taurine: many cats suffered from many classic symptoms of taurine deficiency (retinal atrophy, cardiomyopathy) while eating cat food that had passed AAFCO feeding trials.
Here are the requirements for feeding trials to prove adequacy for adult cat maintenance:
- Only 8 cats need to participate.
- Only 6 of these 8 need to complete the trial (i.e. no more than 25% can drop dead during or be pulled from the trial)
- The trial is only for 26 weeks (6 months)
- Cats are allowed to lose up to 15% of their original body weight and still pass
- No signs of pathological nutritional deficiency must be evident at the end of the trial
- 4 blood values (hemoglobin, packed cell volume, serum alkaline phosphatase and serum albumin) must not fall below the established minimums
Requirements for feeding trials to prove adequacy for pregnant/lactating cats and kittens:
- Only 8 pregnant queens or 8 kittens need to participate
- 6 of these 8 need to finish the trial
- The trial lasts only 10 weeks for kittens, or from estrus until 6 weeks after birth for reproduction
- The weight of the kittens born to the queens must not be below 75% of the “colony average”
- 80% of all kittens that survive 24 hours after being born to the pregnant queens must finish the trial
- For kitten food trials, the kittens must be fully weaned but not older than 8 weeks at the beginning of the trial
- No signs of pathological nutritional deficiency must be evident in the kittens or in the queens and the kittens born to them at the end of the trial
- The same 4 blood values above are checked for mandatory minimums
Unless noted otherwise, information above obtained from Small Animal Clinical Nutrition, 4th ed.
When you look at the guaranteed analysis on cat food labels, you’ll notice that dry food appears to be much higher in protein and fat than canned food. Appearances are deceptive, however, because once you remove the water content, the average can of canned food is much higher in protein than the average dry cat food formula. In order to make an accurate nutrient comparison for any sort of food, you need to compare the food only after all the water is extracted since water content varies so much from food to food, which in turn throws off the percentages which are typically based on weight.
But be aware that dry matter calculations for cat food based on the numbers on the labels are only approximate. That’s because all we’re typically given are maximums/minimums (which yet again gives manufacturers lots of wiggle room). If you’re truly concerned about the nutritional values, write or call the manufacturer and get the as-fed values.
So let’s compare two different types of food from the same company: Wellness.
Wellness Complete Health Salmon dry food contains:
36.6% crude protein
19% crude fat
Not-so-tricky math bit:
Subtract the water content from the food: 100 – 8 = 92; this is the total dry matter percentage
To get dry matter protein, divide the protein percentage by the total dry matter percentage: 36.6 / 92 x 100 = 39.78%
To get dry matter fat, divide the fat percentage by the total dry matter percentage: 19 / 92 x 100 = 20.65%
Not so bad, right? Well, check this out:
Wellness Turkey and Salmon Formula canned food contains:
12.2 % crude protein
8% crude fat
Not more than 78% moisture (it irritates me that their as-fed analysis is more complete for their dry food than it is for their canned)
Not-so-tricky math bit:
Subtract the water content from the food: 100 – 78 = 22% ; this is the total dry matter percentage
To get dry matter protein, divide the protein percentage by the total dry matter percentage: 12.2 / 22 x 100 = 55.45%
To get dry matter fat, divide the fat percentage by the total dry matter percentage: 8 / 22 x 100 = 36.36%
In short: Canned Wellness Turkey and Salmon Formula kicks the Salmon kibble’s ass when it comes to protein and fat content. This holds true for most dry and canned foods. Unless you’re feeding an extremely high-protein dry food like Innova EVO or Wellness CORE, or unless you’re feeding a protein-restricted canned food, a cat eating canned food will always end up eating more protein in a day than a cat eating dry, assuming you feed the same number of calories.