The Pet Food Label

A wealth of information is available on the Pet Food Label but it is practically in secret code to those who do not know what they are reading. All marketed foods must have a “guaranteed analysis.” Here are two samples:

Skippy Premium Canned Food Hill’s Canine R/D (20 pound bag) Guaranteed Analysis (from label) Guaranteed Analysis (from label) Crude Protein: Crude Fat: Crude Fiber: Moisture: Min 8.0% Min 2.0% Max 1.5% Max 82.0% Crude Protein: Crude Fat: Crude Fat: Crude Fiber: Moisture: Calcium: Phosphorus: Carnitine: Min 20% Min 5.5% Max 9.0% Max 26.0% Max 11.0% Min 0.5% Min 0.35% Min 200 ppm

Why Don’t These Numbers Add Up to 100%?
What you are supposed to know but probably did not know is that carbohydrate content is the missing component. One hundred percent minus the sum of the factors listed is understood to be the carbohtdrate content.

Which Food Has More Protein?
It would seem natural to simply read the labels pictured above: the Skippy brand is minimum 8% protein and the Hill’s R/D is minimum 20% protein. Obviously the R/D has more protein, right?

Not so fast.

To compare foods, one has to remember that food consists of water plus the actual nutrients. The water itself does not have any protein. To compare the protein content of two different foods, then, the water factor must be removed before you can acurately compare; that is, the foods must be compared on a dry matter basis only.

For example:

The Skippy above is 82% water and the can’s net weight is 624 grams. Since 82% of that 624 grams is water, that means that the remaining 18%, 112 grams, is the food. The dry matter is 18% of the total can.

The R/D is 11% water, and the bag weighs 9 kg. That means that the remaining 89% of the bag, or 8 kg, is food. Of the total 9 kg bag, 1 kg is water and 8 kg is food.

The reason we need to figure out what percentage of the food is water and what percentage is dry matter is because the percentage of protein listed in the guaranteed analysis on the label is said to be “as fed” rather than on a dry matter basis. But since the water content doesn’t contain any protein, to compare the amount of true protein the pet is receiving from the food, we have to divide the “as fed” percentage of crude protein (from the Guaranteed Analysis label) by the percenage of dry matter.

The Skippy (above) True Protein content =  8/18 = 44%

The R/D (above) True Protein content   =  20/89 = 22%

It is the Skippy food in this example that has substantially higher protein content.

The Moral of This Story
The guaranteed analysis has a tremendous amount of information but it is important to know what the analysis is telling you. Foods cannot truly be compared based on the “as fed” numbers on the label.

Next Installment:
Instead of relying on the clerk at the pet food store or from advertisements to decide what food is best suited for your pet, learning the facts about nutrition will help you separate the facts from the hype. Read Part 2 for more helpful information about nutrition for your pet.