Dry Matter Basis Vs. Calorie Basis in Cat Food

The food you choose to feed your cat can mean the difference between a thriving pet and a nutritionally deficient one. An improper diet can manifest itself in a poor hair coat and skin infections, and predispose the cat to a host of chronic conditions. The first step in understanding the content of your cat’s food is understanding the nutritional information on the label. Whether it is canned food or dry kibble, all nutritional content percentages are calculated on a “dry matter” basis.

  1. Dry Matter

    • All cat food contains moisture, even dry kibble. In order to calculate the nutritional value in a way that would translate to any food no matter what the moisture content, standard practice is to use percentages of the food’s total dry matter. Foods with higher moisture content would appear less nutritious than they really are because water itself contains no calories or vitamins, so analysts subtract the water content and base their calculations solely on the nutritional value of the dry matter. A food that is labeled “20% moisture” would contain 80 percent dry matter, and the nutritional content is based on that 80 percent.

    AAFCO Standards

    • The Association of American Feed Control Officials (AAFCO) has set standards for the nutritional quality of pet foods, and the calculations are based on dry matter. A diet for an adult cat must have a minimum of 26 percent protein, nine percent fat and 10 to 20 percent taurine. Keep in mind that these standards are only minimums, and that a food that exceeds them will be even better for your cat.

    Calculating Content

    • In determining the true nutritional value of your cat’s food, some calculations are necessary. For instance, if the food is labeled as having 10 percent moisture, it is naturally 90 percent dry matter. If the label states the protein to be 26 percent, the fat to be nine percent and the taurine to be 20 percent, we must divide the content percentages by the amount of dry matter to get the true amount; in this case, 29 percent protein, 10 percent fat and 22 percent taurine. Although the figures as listed on the label simply meet the AAFCO standards, the calculations show that the true figures exceed them.

    Ingredients

    • The amount of ingredients themselves are based on a dry matter basis as well. The meat named in the flavor of the food, for example, “Tuna Cat Food”, must have that meat in at least 95 percent of the food. If the word “dinner” is added, for example, “Tuna Dinner for Cats”, between 25 and 95 percent of the food must be tuna. If more than one ingredient is listed in the name of the food, it must be the predominant ingredient. The ingredient label is required to list ingredients from the most abundant to the least abundant.

    Special Cases

    • Cats with chronic health conditions may have special dietary needs that are best met with a prescription cat food that may be lower in protein, higher in antioxidants or hypoallergenic, depending upon the condition. Obese cats who must lose weight can do so without a special food, if calories are taken into consideration and each individual cat’s needs calculated specifically. The calories listed on the cat food label are not calculated on a dry matter basis, because they are a firm number instead of a percentage, and water does not add calories. If the label lists broth as the source of moisture, it will add calories, and may add minute amounts of protein and fat that are not taken into account in the dry matter calculations. These foods may also have the nutritional values listed on a calorie-percentage basis.