how to calculate carbs in dry dog food
Calculating a Dog Food Diets Protein, Fat, Carbs, and Fiber
[Updated July 19, 2017]
It is not easy to figure out how much fat and other nutrients are really in the food you feed, whether its kibble, canned food, or a home-prepared raw or cooked diet. Here are some tips that can help.
Methods of Nutrition Measurement
There are three different ways of measuring amounts of protein, fat, carbohydrates, and fiber in foods:
1.Percentage of dry matter
2.Percentage of calories (does not apply to fiber)
3.Grams per 1,000 calories
Dry matter percentages are easiest to use for commercial foods. Grams per 1,000 calories or percentage of calories are simpler ways to measure nutrients in a homemade diet.
When Feeding Your Dog Commercial Foods:
Pet food labels give you some, but not all, of the information you need in order to really know the nutritional composition of your dogs diet.
-The percentages of protein, fat, and fiber shown on dog food labels are guaranteed minimums and maximums, NOT actual amounts. The real amount of fat in particular may be much higher than what is shown on the label of some canned and raw diets. If your dog needs a low-fat diet, look for products that are lower in calories than similar foods.
For more accurate information, contact the company that makes the food youre interested in and ask them for a nutritional analysis showing the actual amount of protein, fat, fiber, ash, and moisture, as well as the number of calories in the food. Editors note: Some pet food makers (particularly small companies) may not have a complete nutritional analysis of their products. In our opinion, this reflects a lack of adequate research and investment in the product. When feeding a special needs dog, wed look to a company who has this current information on hand.
-The percentage of carbohydrates is not included on most labels or nutritional analyses. To calculate the percentage of carbohydrates in a commercial diet, subtract the percentages of protein, fat, moisture, crude fiber (an indigestible part of carbohydrates), and ash from 100. This percentage may be shown as nitgrogen-free extract (NFE) on a nutritional analysis.
-Total dietary fiber is likely much higher than the crude fiber shown on the label. If dietary (soluble plus insoluble) fiber is not shown on a complete nutritional analysis, there is no way to calculate it.
When Feeding Fresh Foods:
When feeding a home-prepared diet comprised of fresh food ingredients, it can be a bit more challenging to calculate some of the nutrient values that youd like to know when feeding a diabetic dog.
-To calculate the caloric content of the food, look up the ingredients or enter a recipe on NutritionData.com. The number of calories from protein, fat, and carbohydrates, along with the total calories, are given in the calorie information section, and the calorie percentages are shown in the caloric ratio pyramid.
-To calculate the grams of protein, fat, etc., per 1,000 calories, divide grams of any nutrient by total number of calories, then multiply by 1,000 to get grams per 1,000 kcal. For example, raw skinless chicken breast contains 6.5 grams of protein, 0.3 grams of fat, and 30.8 calories per ounce:
6.5 30.8 x 1,000 = 211 grams of protein per 1,000 kcal
0.3 30.8 x 1,000 = 9.7 grams of fat per 1,000 kcal (GFK)
As Fed versus Dry Matter
The percentages of protein, fat, etc., shown on a pet food label 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 other nutrients. Kibble generally contains about 10 percent moisture; wet foods (canned, frozen, or fresh) contain as much as 80 percent or more moisture.
So, think about it: When a label says that a food contains (for example) 4 percent fat, in order to really understand how much fat you are about to feed your dog, you also have to know how much moisture is in the food. What you really want to know is 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, then, requires the conversion of the nutrient values from as fed to dry matter. Dont worry; it sounds technical, but its easy to do.
-To calculate dry matter (DM) percentages, first determine the amount of dry matter by subtracting the percentage of moisture from 100. Then divide the as fed percentage by the amount of dry matter to get the dry matter percentage. For example, if a canned food has 75 percent moisture and 4 percent fat:
100 75 = 25 percent dry matter
4 25 = 16 percent fat on a dry matter basis
How To Calculate Carbohydrates in Dog Food: Math Explained
Working out carbohydrate levels of your dogs kibble is harder than you think. Many people want to select diets that are lower in carbohydrates, but it is easy to be misled by brands that tout a fashionable lack of grains but that fill the product with other vegetable starches instead.
If you want to make a good guess as to which kibbles have less carbs, heres what you do. Dog food labels all include a guaranteed analysis, which must state the percentage of the product that is made up of fat, protein, and water. You also need to take into account the ash content, which includes various minerals and other largely inert trace materials. Basically, the analysis involves burning the product up and whatever is left over is the ash. Ash content is usually not reported, so I would suggest that you estimate that it is about 10 percent of any dry dog food.
You can arrive at a rough estimate of carbohydrate content by subtracting the percentage that is fat, protein, water, and ash from the total, and assuming the remaining material is carbohydrate keeping in mind that you are using a number of rough estimates here for a somewhat variable product. But in my opinion this estimate is good enough to compare different kibbles to see which has a lower overall level of carbohydrates.
As an example I selected the least and most expensive brands at my grocery store. (I dont want to look like I am dissing or endorsing any given brand so I wont give the names.)
Mainstream brands:
Brand 1:
- Protein 18 percent
- Fat 9 percent
- Moisture 14 percent
100 (18 + 9 + 14 + 10) = this product is approximately 49 percent carbohydrate.
Brand 2:
- Protein 25 percent
- Fat 14 percent
- Moisture 10 percent
100 (25 + 14 + 10 + 10) = this product is approximately 41 percent carbohydrate.
So it looks like mainstream brands fall at around 50 percent carbs. My goal is to find a product that gets me as close as possible to a low-carbohydrate diet (less than 30 percent, optimally closer to 10 percent). Given that it is hard to make kibble without some kind of carb to make a stable, dry product, this will probably mean just the lowest percentage I can get that I can afford.
In any case, 50 percent strikes me as too high. (After going through all the brands at the supermarket, the lowest barn value I found was in a mid-priced brand and was 36 percent. This has become my back-up brand for when I cant get to the specialist pet food store, or an unexpected bill has put a squeeze on my budget.)
Next I turned to the top and bottom priced grain-free kibbles from the big box pet store.
Grain-free brands:
Brand 3:
- Protein 23 percent
- Fat 14 percent
- Moisture 10 percent
100 (23 + 14 + 10 + 10) = this product is approximately 43 percent carbohydrate.
Forty three percent is higher than some of the mainstream brands. So, grain free isnt striking me as a terribly impressive claim, unless you think the dogs wolf ancestors subsisted on roaming herds of wild sweet potatoes or you have a dog with issues specific to gluten rather than carbs in general. But some dogs do have sensitivities to specific ingredients, so you might want to pay attention to carbohydrates types, levels of fibers, calories, and other factors. Then if a food your dog does well with changes formulation or goes off the market, you have some idea what to look for as a replacement.
Brand 4:
- Protein 34 percent
- Fat 16 percent
- Moisture 10 percent
100 (34 + 16 + 10 + 10) = this product is approximately 30 percent carbohydrate.
That is pretty good, probably good enough for my purposes. It has become my go to brand.
Finally I also looked up some specifically low-carbohydrate brands online.
Low-carbohydrate brands:
Brand 5:
- Protein 42 percent
- Fat 18 percent
- Moisture 10 percent
100 (42 + 18 + 10 + 10) = this product is approximately 20 percent carbohydrate.
This brand actually provides a reported carb value of 18 percent. Which, given that my estimate is approximate, sounds about right.
Brand 6:
- Protein 38 percent
- Fat 20 percent
- Moisture 10 percent
100 (38 + 20 + 10 + 10) = this product is approximately 20 percent carbohydrate.
This brand provides a reported carb value of 17.5 percent.
Overall, mainstream brands are probably about 50 percent carbohydrate, but go as low as 36 percent for the brands I looked at. Grain-free brands may or may not be much lower than that depending on how they are formulated. Low-carbohydrate diets have about half the carbs, and they are probably going to come right out and tell you the percentage, so you dont need to mess around trying to calculate it yourself.
Regardless of which diet you choose or whether you go for a freeze-dried, wet, or raw diet instead it is good to know as much as you can about what you are feeding your dog without becoming obsessed. (Well, maybe just a little bit.)
Read more on feeding your dog:
Featured Image Credit: Maximilian100, Shutterstock
How to Calculate Carbohydrates in a Pet Food
How to Calculate Carbohydrates in a Pet Food
Carbohydrates dont need to be listed on the label of pet foods in Australia, but we can use a simple calculation to offer us a rough idea. Its not perfect, and Ill explain why, but the following method is how to calculate carbohydrates in a pet food:
100 Protein % Fat % Moisture % Ash %
Heres a carbohydrate calculator for dog food and cat food for your convenience. If moisture and ash are not listed on your pet food, you may use average values of 10% moisture and 8% ash:
The above calculator will give you a rough idea, but there's a little more to it than that.
Other factors to consider are undisclosed moisture and ash percentages and variance from min & max percentages.
Moisture & Ash
Moisture and ash are usually listed, but as these percentages aren't required to be listed we can use an average 10% moisture and 8% ash for dry food only. Wet foods contain significantly more moisture.
Min & Max
We often find percentages are listed with a guaranteed minimum or maximum. This makes our simple calculation somewhat vague. If a pet food contains Protein (min) 20% then it's possible the protein, on average, is higher.
How to Calculate Carbohydrates: An example
Let's say a dry dog food contains 20% protein, 10% fat, 10% moisture, and 8% ash:
100 - 20 - 10 - 10 - 8 = 52
This product would contain approximately 52% carbohydrates.
So that's it, that's how to calculate carbohydrates in a pet food.
Calculating Carbohydrates & Dry Matter Basis (DMB)
In todays blog we are going to look at DMB and I do not mean Dave Matthews Band! We bring up dry matter basis (DMB) on a constant basis in our Facebook group Diabetic Dog Owners because our dogs need to eat lower fat and carbohydrates. As mentioned in previous blogs our dogs pancreas is faulty, they require insulin therapy to live and lower fat due to being prone to pancreatitis.
This can be a bit confusing for people that are not fans of math, but do not worry we have a dry matter basis calculator to help! Lets dive into how we calculate dry matter basis and carbohydrates in commercial and prescription foods.
Theguaranteed analysis on dog food labels gives you the amounts ofprotein/fat/fiber before moisture is removed. When moisture is removed from the equation, we get the true quantity ofthe content we are interested in; this is called dry matter basis or DMB. Most dog food analysis does not have carbslisted, so we must manually calculate what they are. Then, we calculate the percentage ofcarbohydrates on the DMB.
Forcalculating carbohydrates you need the following percentages from the guaranteed analysis:
- Protein
- Fat(min or max; if only min is listed use that, if max is listed use thispercentage)
- Fiber
- Ash(usually not listed; the amount will be listed below)
Ashis usually not listed in the guaranteed analysis, if not listed use thefollowing:
Wet food 2.5
Dry food 8
To calculate carbs, you can either use this free calculator below, or you can figure it out manually. Please click on the link below to take you to the calculator. You can save this carbohydrates and Dry Matter Basis calculator on your home screen for future use.
PetTest Carb & Dry Matter Basis(DMB) Calculator
Tocalculate carbs manually:
- Addprotein, fat, fiber, moisture and ash
- Subtractby 100
- Totalis carbs
Example:
100 58 = 42
Therefore,the carbohydrate content is 42%. Now weneed to calculate what the carbs are on a DMB.
Tocalculate DMB you can use the calculator above, or you can do it manually.
Youneed:
- Moisturecontent
- Quantityof carbs
Forexample, using 42 for carbs in quantity and 10 for moisture:
Foodis 46.7% carbs on a DMB.
You can use the equation above to get the dry matter basis of protein, fat & fiber as well.
Phew! That was a lot of math, if you do notunderstand it do not worry because this can be confusing to many of us. When in doubt get the calculator out!
Sincewe are talking about carbohydrates, I want to share a carb free treat that youcan make at home! The Dog Gummies are zerofat, zero carb and a great source of collagen. There are different types of gelatin you can use in case your dog has allergiesand can they be purchased easily on the internet.
Do you have questions or want to add something about calculating dry matter basis? Comment below to get a conversation going!
Formore conversations, photos, and giveaways check outPetTest on Facebook and Instagram.
Ifyou are looking for a community to join for support, I have been an admin forover four years in DiabeticDog Owners. CanineDiabetes Support and Information can be found on Facebook as well.
