Dry Matter Value Forumula
- Look at the "Guaranteed Analysis" on a label
- Subtract the moisture percentage from 100
- Divide the resulting figure into the crude protein figure (disregard decimals when dividing)
- The result will be a close approximation of protein by dry matter value
(You can use the same formula to calculate the percentage of fat or fiber by dry matter value.)
Here are figures from three different cat foods I happened to have on hand. They are from three different manufacturers, which shall remain anonymous for purpose of this exercise.
- Brand A Premium Canned Food: Protein, 8.5% | Moisture, 78%
- Brand B Premium Dry Food: Protein, 32% | Moisture, 10%
- Brand C "Supermarket Brand" Canned Food: Protein, 10% | Moisture: 78%
Brand A: Using the formula above, and subtracting the moisture from 100%, we divide the remainder, 22 into the 8.5 protein content for a result of 38.5% protein by dry matter.
Brand B: 100 minus 10 equals 90, divided into 32 gives us 35.5%.
Brand C: 100 minus 78 equals 22 divided into 10 for 45%.
You can see in the example given that the two canned food brands contain more dry matter protein content than Brand B, a dry food, which at first glance seems to contain far more protein. In fact, by this test alone, one might think that Brand C (the "supermarket" brand) is superior for protein content.
Not so fast!
Actually, the first two listed ingredients on Brand C's label are "meat by-products," and "poultry by-products," which were listed under "What to Avoid" in the first part of this series. The protein quality of this "supermarket" brand simply does not make the cut.
The 95%, 25%, 3% Rules
AAFCO has provided certain other rules for "truth in advertising" in cat foods. Don't let those fancy designations such as "gourmet" or "feast" slip one past you. With these rules you'll know at least the minimum your cat is getting of the advertised ingredient.
Here are the rules:
- The 95% Rule
A cat food may not be labeled simply "Chicken for Cats," or "Chicken Cat Food," unless it contains 95% or more chicken by total weight of the product.
- The 25% Rule
Foods labeled "Chicken Entre," "Chicken Dinner," "Chicken Feast," or the like, must contain 25% to 95% chicken. Combinations, such as "Chicken and Beef Dinner" must contain a total of 25% to 95% of the combined meats, listed in order of quantity, and the second meat listed must comprise at least 3% of the total weight. (Imagine ordering a "steak and lobster" dinner and finding the "lobster" will barely fill a fork.)
- The 3% Rule
A food labelled "Kitty Stew with Chicken" must contain 3% or more chicken. ("With" is the optimum word here.)
Barely worth mentioning here, but if you see something similar to "chicken flavored," be assured that the product is unlikely to contain any chicken at all, as long as there is a "sufficiently detectable" amount of chicken flavor. Since these "flavors" may be the result of digests or by-products of the named animal, I'd avoid these at all costs.
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