how to calculate crude fat in dog food
Fats for Dogs
Fat usually gets a bad rap, but its actually an important nutrient for dogs. Pet parents need to ensure their dogs get the right amounts and the right types of fat in their diets. This is made easier because, unlike with people, too much bad fat in a dogs diet doesnt have much of an effect on their cholesterol levels and their risk of heart attack or stroke.
Heres what you should know about the type and amount of fat dogs need.
Do Dogs Need Fats in Their Diet?
Fats are an important part of a dogs diet, but its helpful to divide fats into two types to understand their different functions.
Triglycerides
The fats most commonly found in the body and the diet are triglycerides, which are composed of three fatty acids attached to a glycerol molecule.
In the diet, triglycerides:
In the body, triglycerides:
Store energy
Store essential fatty acids
Provide cushioning
Reduce heat loss
Transport molecules
Are structural elements in cell membranes
Help conduct nerve impulses
Fatty acids
Individual fatty acids play many roles in cell structure and function. Only small amounts of fatty acids are needed in the diet, but they are vitally important. Here are a few of their most noteworthy roles:
Omega-6 fatty acids like linoleic acid and arachidonic acid promote skin and coat health.
Omega-3 fatty acids like eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA) reduce inflammation.
Docosahexaenoic acid (DHA), an omega-3 fatty acid, encourages healthy development of the nervous system and eyes.
Fatty acids can be divided into two categories: essential and nonessential.
Essential fatty acids (linoleic acid and alpha-linolenic acid for dogs) must be supplied by the diet because the body cant make enough of them on its own.
Nonessential fatty acids can be made by the body, but higher levels may be necessary at certain times of life. For example, DHA is added to high-quality puppy diets to promote brain and eye development.
Sources of Fats for Dogs
Triglycerides and fatty acids are part of a variety of ingredients that are commonly found in dog foods. Animal sources like chicken fat or beef fat provide a lot of triglycerides and arachidonic acid. Ingredients like fish oil, purified algal oil, and flaxseed oil add omega-3 fatty acids, while corn oil, soybean oil, sunflower oil, and canola oil contain primarily omega-6 fatty acids.
All of these (and other) ingredients can be healthy sources of fats and fatty acids when used in combination. Whats most important is that a dogs diet provides an appropriate level of overall fat (triglycerides), all essential fatty acids, and a good balance between omega-6 and omega-3 fatty acids.
How Much Fat Does My Dog Need?
For a dog food to be labeled nutritionally complete and balanced, the manufacturer must follow guidelines from the Association of American Feed Control Officials (AAFCO). The AAFCO minimum crude fat level for dogs is 5% for adults and 8% for puppies. The term crude fat is used on nutrition labels to note how much total fat is included in the product. The word crude says nothing about the types of fats or their quality; it simply refers to the method used to test the products fat level.
The ideal fat content of a dogs diet will depend on many factors. Growing puppies, dogs that are pregnant or nursing, very active dogs, and dogs who need to gain weight generally need higher fat levels. Dogs that are overweight, inactive, or suffer from certain types of health conditions like pancreatitis or hyperlipidemia can benefit from low-fat diets.
Talk to your veterinarian if you have concerns about the amount or types of fat in your dogs diet.
How to Calculate How Much Fat Is in Your Dogs Food
AAFCOs nutrient guidelines are reported on a dry matter basisthat is, the percentage of the nutrients if all the water were taken out.
Dry diets contain so little water that you can look at the crude fat level on the guaranteed analysis panel on the package to get a general idea of how much fat the food contains.
But if you feed wet food, youll need to do some math:
Find the percent moisture listed in the guaranteed analysis and subtract that number from 100. This is the percent dry matter for the food.
Divide the fat percentage on the label by the percent dry matter for the food and multiply by 100. The resulting number is the fat percentage on a dry matter basis.
For example, a canned food label might list its moisture content as 82% and its crude fat as 3%. To calculate the foods fat level on a dry matter basis, your calculations would be 100-82=18 and then 3/18 x 100 = 16.7% fat
Should You Supplement Your Dogs Diet With Certain Fats?
As long as youre feeding foods that meet AAFCO guidelines, you do not need to worry about adding extra triglycerides to your dogs diet. In fact, doing so can be dangerous.
Feeding dogs high-fat foods, including fatty human foods like meat trimmings, can lead to a potentially life-threatening condition called pancreatitis. And because fats contain almost three times as many calories as proteins and carbohydrates, adding extra fat to a dogs diet can lead to obesity.
On the other hand, supplementing your dogs diet with omega-3 or omega-6 fatty acids can be beneficial. Veterinarians often recommend omega-3 fatty acid supplements as part of the treatment for inflammatory diseases like osteoarthritis or allergic skin disease. Omega-3 fatty acids can also play a role in the treatment of heart disease and cancer.
Salmon oil, other cold-water fish oils, algal oils, and to a lesser extent, flaxseed oil, are excellent sources of omega-3 fatty acids for dogs. Dogs with skin problems may also benefit from omega-6 fatty acid supplementation.
Talk to your veterinarian if you have concerns about the amount or types of fat in your dogs diet.
Featured Image: iStock/O_Lypa
Dry Dog Food Labels: How to Compare Fat, Protein, and Carbs
Federal and state laws require pet food makers to put information about the protein and fat content of their products on pet food labels. Unfortunately, few people understand this critical information, making their purchasing decisions based on some of the most insignificant words or pictures on the label. Heres what you need to know to understand whats in the bag or can and to compare one food to another.
Minimums, maximums, and actual amounts
Every pet food label is required to display a guaranteed analysis that includes the minimum percentages of crude protein and crude fat and the maximum percentages of crude fiber and moisture that are present in that food as fed as they are in the foods present form.
Protein and fat are the most important (and costly) nutrients in a dogs food, so these are reported as guaranteed minimums; this ensures that dogs receive the minimum amounts necessary for health.
Moisture (water) and fiber, being empty of nutrients, are listed by their maximum amounts; this ensures that consumers know the maximum amount of the foods contents that is without nutrients.
All these amounts are subject to surveillance, testing, and enforcement by feed control officials in every state where the product is sold.
Its important to understand that the minimum and maximum amounts listed in the guaranteed analyses are just that: minimums and maximums. The actual amount of those nutrients may be significantly different. For example, the minimum fat guarantee on a label may be 8%, but the product might contain 15% fat or more. Similarly, a product with a maximum guarantee of 5% fiber may actually contain only 1%.
Some product manufacturers report more accurate numbers for their products nutrients in whats usually called a typical nutrient analysis. These analyses may reflect nutrient levels that have been calculated by a computer analysis of the products ingredients and formula, or levels that have been determined by laboratory tests of the product. The most transparent, consumer-friendly pet food makers publish typical nutrient analyses for all of their products on their websites. Other companies make these available by request and some companies dont make them available at all!
If its critical to your dogs health that you feed a very specific amount of protein (for a dog with diminished kidney function, for example), fat (say, for a dog who is prone to pancreatitis), or fiber (for a dog prone to constipation or diarrhea), wed recommend considering only those foods with a readily available typical nutrient analysis.
Further, for the most precise comparison to other products and products of different types (canned, dry, etc.), its ideal if these analyses list their nutrient contents in two ways: as-fed (meaning, the food as it is presented in its package) and as dry matter (the nutrient levels in the food if all of the water were removed).
Why the dry matter values matter
Have you ever wondered about the disparity between the amounts of protein or fat listed on the canned (or fresh frozen) food you give your dog, and those on the bag of dry or freeze-dried food he eats? A good-quality dry food may have a minimum of 28% protein listed, while a comparable canned food may be labeled as having just 7% protein. How can a dog live on the (seemingly) paltry amounts of nutrients in canned and fresh foods?
Answer: A dog can subsist on those amounts because they are anything but paltry! In fact, high quality canned and fresh/frozen foods usually contain more fat and protein than high-quality dry foods if you go by the dry matter values.
In order to directly compare the protein or fat content of one type of food (i.e., canned, dry, raw frozen, or freeze-dried) to another type, you need to consider them on a level playing field. Each of these types of food contains highly disparate amounts of moisture, which affects the as fed percentages. The nutrient levels in high-moisture foods are, in effect, diluted.
To compare the nutrient levels in products with disparate amounts of moisture, you have to remove all the moisture from each product. This is easy to do mathematically.
The first step in comparing any two products of different types is to convert the as-fed amounts on the label to dry matter (DM) values. Do this by subtracting the amount of moisture on the label from 100. The result is the foods dry matter or DM factor.
100 moisture % = dry matter or DM factor
Then you can divide any listed nutrient percentage by the DM factor to determine its dry matter percentage. For example:
Protein % DM factor = DM protein
Multiply by 100 to show it as a percentage
Example Label #1 (dry dog food)
Protein (min) 28%
Moisture (max) 9%
100 Moisture % = DM factor
100 9 = 91
The DM factor for this food is 91
To determine the percentage of dry matter protein in this food, take the listed protein percentage (in this case, 28) and divide it by the foods DM factor (91):
28 91 = 0.31
This food is 31% protein by DM
Lets look at a canned food. The math looks a little different, because the moisture content is so high in canned foods, which makes the dry matter factor number small. The high amount of moisture also makes the as-fed nutrient amounts small (they are literally diluted!). But you use the same formula and you may be surprised by the result. Check it out:
Example Label #2 (canned dog food)
Protein (min) 7%
Moisture (max) 78%
100 78 = 22
The DM factor for this food is 22
To determine the percentage of dry matter protein in this food, take the listed protein percentage (in this case, 7) and divide it by the foods DM factor (22).
7 22 = 0.31
This food is 31% protein by DM
Did that surprise you? Notice that both the dry food in Example Label #1 and the canned food in Example Label #2 contain the same amount of dry matter protein (31%), even though the as fed numbers on their labels look very different. If you were trying to find a dry and a canned food that contained a moderate and consistent amount of protein for your dog, youd do well to run these calculations, to make sure that both types of food offer an appropriate (and similar, if not matching) amount of protein.
What about carbohydrates?
Carbohydrates are not usually listed on a guaranteed analysis, but, if youve gotten this far, they are easy to compute. But in order to do so, we have to add one more nutrient to the calculation.
The ash content of dog food is rarely discussed, even though some pet food manufacturers list the maximum amount of ash in their products on the guaranteed analysis. This is not required, but its helpful for dog owners who know what ash is.
Ash is essentially what would be left over if you were to put the food in an oven and burn away everything that could burn; whats left are all the minerals in the food. Calcium and phosphorus constitute the vast majority of these minerals (interestingly, you could use the ash total as a rough estimate of how much calcium and phosphorus are in the diet), but even the iron, copper, zinc, magnesium, selenium, and the rest of the trace minerals in the food contribute to the total amount of ash.
Though all dog foods need to contain some ash as they all need to contain the minerals required by dogs low-quality foods often contain fairly high levels of ash, as much as 10% or more. High levels of ash can impede a dogs ability to absorb other nutrients which is why you will almost never see the amount of ash reported by the makers of cheap, low-quality foods, but you may see low amounts of ash voluntarily included in the guaranteed analysis by makers of high-quality foods.
Back to carbohydrates: In order to calculate what percentage of a food is carbohydrates, add the as-fed (label) percentages for protein, fat, fiber, moisture, and ash, subtract their total from 100, and divide the result by the DM factor.
If you cant find the ash content for a particular food, you can use an estimate of between 5% and 9% as the ash percentage of a canned or dry food. You can use an estimate of between 1% and 4% for the ash percentage of most fresh or frozen raw foods.
Lets look at another example:
Example Label #3
Protein (min) 28%
Fat (min) 18%
Fiber (max) 3%
Moisture (max) 9%
Ash (max) 9%
To find the carbs in this food, add the label percentages for protein, fat, fiber, moisture, and ash:
28 + 18 + 3 + 9 + 9 = 67
Subtract this total from 100:
100 67 = 33
Divide this result by the dry matter factor (for this food, the DM factor is 91):
33 91 = 0.36
This food is 36% carbohydrates by DM
Dont be intimidated!
These calculations are not difficult, just a bit tedious. If you follow along through a few more, youll begin to see how easy it is and how much more you can learn about your dogs food by doing some math.
Example Label #4 (raw frozen food)
Crude protein 12% minCrude fat 11% minCrude fiber 1% maxMoisture 72% maxAsh 3% max
Find the dry matter factor by subtracting the moisture % from 100:
100 72% moisture = 28 DM factorFind the dry matter protein percentage by dividing the labels protein (12%) by the DM factor (28):
12 28 = 0.43
This food is 43% protein by DM
To calculate its carbohydrate percentage, add protein + fat + fiber + moisture + ash:12 + 11 + 1 + 72 + 3 = 99Subtract that result from 100:
100 99 = 1
Divide that answer by the DM factor (28):
1 28 = 0.035
This food is 3.5% carbohydrates by DM
This is a very low-carb food, typical of many raw-food diets. (Remember, dogs dont have a nutritional requirement for carbohydrates; they can live on fat and protein alone. Dietary fiber offers some functional benefits read Dietary Fiber for Dogs but many dogs thrive on low- or no-carb diets.)
Ok, just one more. For fun, lets look at a food thats on the other end of the carb-content scale. This one is a brand every dog owner knows:
Example Label #5
Crude protein 21% min
Crude fat 10% min
Crude fiber 5% max
Moisture 12% max
Ash (not listed, so estimate) 6%
Find the dry matter factor by subtracting the moisture % from 100:
100 12% = 88 DM factor
Find the dry matter protein percentage by dividing the labels protein (21%) by the DM factor (88):
21 88 = 0.24
This food is 24% protein by DM
To calculate its carbohydrates, add the labels protein + fat + fiber + moisture + ash:
21 + 10 + 5 + 12 + 6 = 54
Subtract that result from 100:
100 54 = 46
Divide that answer by the DM factor (88):
46 88 = 0.52
This food is 52% carbohydrates by DM
The more you know . . .
When I first came across descriptions of how to calculate dry matter percentages, my brain would freeze. But with practice, it has become easy and even fun especially when I can exclaim over the carb counts for most grocery-store kibbles. Carbohydrate-wise, we might as well just feed our dogs cinnamon buns! I hope you find this important subject as interesting as I do.
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