The percentages of nutrients shown in the guaranteed analysis section on a pet food label (protein, fat, fiber, moisture) are expressed “as fed” – meaning, as the food is delivered in its package. Some percentage of the food is comprised of moisture (water), which of course contains no protein, fat, fiber, or any other nutrient. Kibble generally contains about 10% moisture; canned foods usually contain about 78% moisture.
So, when a canned food label says that a food contains (for example) 9% fat, in order to really understand how much fat you are thinking about feeding to your dog, you have to remove the moisture from the equation; you want to know how much fat (in this example) is in the food part of the food – the “dry matter.” Any serious discussion of nutrition, or comparison of dry and wet diets, requires the conversion of the nutrient values from “as fed” to “dry matter.”
To calculate the nutrient levels in a food as dry matter (DM) percentages, first determine the amount of dry matter in the product. You do this by subtracting the percentage of moisture from 100. Then, divide the “as fed” percentage of the nutrient you are curious about by the amount of dry matter; that will give you the dry matter percentage.
For example, if a canned food has 78% moisture and 9% fat as fed (as seen on the guaranteed analysis):
- 100 – 78 = 22% dry matter (DM)
- 9 ÷ 22 = .40 = 40% fat DM (on a dry matter basis)
To compare that product to a dry food, do the same calculation for the dry food you may have been feeding. We’ll use the numbers from a bag of food our dogs are currently eating; the guaranteed analysis says it contains 10% moisture and 13% fat.
- 100 – 10 = 90% DM
- 13 ÷ 90 = 14% fat DM
So the canned food contains a little more than three times the amount of fat than the dry food does, on a dry matter basis. Yowsa! We’d be careful if we were considering adding some of this food to our dog’s diet – we’d add only small amounts – and we certainly wouldn’t switch quickly from the dry food to this canned food. Doing so would just be asking for digestive upset, and could provoke a pancreatitis attack in susceptible dogs.
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I am a pup to WDJ, but I was lucky to come across your website. The things I have already learned just from reading here are both helpful and exciting. I am eager to share what I have learned with my 4-paw family. I have a 5 yr old white wolf breed, named “Woof” and her son “Fang”, which is a 2 yr old Great Pyrenees (& wolf naturally) mix.
However, 8 months ago I lost my best friend of 14 years, Boo, my Rottweiler. She died of cancer, but she gave it a good battle. Woof and I were both depressed, but we helped each other make it through. So with that brief summary, I was curious if you ever published an article about just how helpful dogs (animals) can really be towards the health of humans? Boo taught me so much about dogs and myself, during those 14 years. I just think it might be helpful to others to inform, or even remind, us of all the health issues that dogs are actually capable of assisting us with, during our lives. I also thought it might be more relevant with this time in our lives of COVID-19 causing most of us to be limited in our socializing. Any health accomplishments we might can share with others could only help, Right?
Looking forward to more information shared through WDJ.
I am a fan of WDJ, and look forward to your lists. I do not understand though why there is not a percentage of carbohydrate listed on any dry dog food package. My splendid Standard Poodle who will be 11years old next month, wound up in emergency surgery at the AMC in October with Bloat. We were lucky. Then the following month he was diagnosed with DCM heart condition. He had been off grain-free for 2 years…it was too gassy. He now needs low carb and low fat…yes I do some cooking, but the kibble is a problem .
Tasso and I are a therapy dog team and have worked at the VAH, the NYC Marathon at Ft. Wadsworth on S.I. at 5:30 AM , schools, and now will do the R.E.A.D program. he still jumps the 3 foot fences in Central Park, and I want to keep him healthy.
For Katrina Phipps: There is a terrific tee shirt that says: All Dogs are Therapy Dogs, most are Freelance.