How do I Calculate the Calorie Content?
Where a label calorie content statement is required or simply desirable, it may be calculated from the same proximate analysis data used for setting guarantees. Unlike guarantees, it is NOT declared as a minimum or a maximum, but as an average based on multiple proximate analysis data.
The calorie content of a food is dependent on the amounts of crude protein, crude fat, and carbohydrate in the product. Carbohydrates are not measured directly, but can be estimated by calculating the “nitrogen-free extract” (or NFE) in the product. This is determined simply by subtracting the average of each of the other components (percent crude protein, crude fat, crude fiber, moisture AND ash) from 100 [see the following example].
The next step is to multiply each of the average percentages for the calorie-containing nutrients by the appropriate “modified Atwater” value. Protein and carbohydrate are assigned a value of 3.5. Fat is much more calorie dense, hence has a value of 8.5. The results of the three calculations are added. Then, to convert the answer to kcal/kg (the units required on the label), the sum is multiplied by 10.
Some lab reports include calorie values. However, this information is only useful and can be used in lieu of the above calculations if the lab is familiar with calorie calculations specifically for pet foods. A laboratory that primarily analyzes human foods will not use the same modified Atwater values in its calculations, hence will give you an inaccurate calorie content number.
Also useful information is the number of calories per treat or cup of product. First needed is the weight of a single treat or a cup of product in grams. Dividing the kcal/kg value as determined above by 1000 converts it to kcal per gram. Then, multiplying by the number of grams per treat or cup gives you the calories per treat or cup.
Example: Calculating calorie content from proximate analysis data
Nitrogen-Free Extract = 100 – (crude protein + crude fat + crude fiber + moisture + ash)
Metabolizable Energy = [(3.5 X crude protein) + (8.5 X crude fat) + (3.5 X nitrogen-free extract)] X 10
Calorie content (ME)= 3688 kcal/kg; If a treat weighs 10 grams apiece, the calories per treat = 3688/1000 X 10 = 36.9 kcal/treat; If a food weighs 120 grams per cup, the calories per cup = 3688/1000 X 120 = 442.6 kcal/cup
For instance, what exactly does it mean when the label states that the food meets the AAFCO standards for "maintenance" and "growth and maintenance" and "all life stages"?
All pet foods, including snacks, treats, cookies, chews, rawhides, supplements, and complete and balanced products are regulated by the states under the state’s feed law and pet food regulations, if the state has adopted such legislation.
What are the nutritional requirements for complete and balanced pet foods?
While it is the state that regulates all animal feed and pet food, AAFCO has determined the nutritional standards for complete and balanced pet food. Please know that AAFCO does not regulate, test, approve or certify pet foods in any way. AAFCO establishes the standards, and it is the state’s AND the pet food company’s responsibility to ensure that complete and balanced pet foods meet AAFCO’s nutritional standards.
The AAFCO Dog Food (and Cat Food) Nutrient Profiles, the AAFCO Dog and Cat Food Feeding Protocols and the product family criteria are described in detail in the AAFCO Official Publication (OP).
How can I calculate the total crude protein percentage in certain pet food?
AAFCO does not have a “pet food nutrient calculator”. That means you must calculate the required protein yourself. Let’s work through the calculations.
AAFCO has approved the AAFCO Dog Food Nutrient Profiles that determines the minimum (and some maximum) levels of nutrients in complete and balanced pet food based upon the particular life stage of the pet. The minimum levels for Crude Protein are:
For Growth and Reproduction diets (for puppies and pregnant/nursing dogs), the minimum level of Crude Protein on a DRY MATTER basis (which means all the moisture in the dog food has been removed) is 22.0%.
For Adult Maintenance diets, the minimum level of Crude Protein on a DRY MATTER basis is 18.0%.
Guarantees on pet food labels are listed on an “AS FED” or “AS IS” basis, and all pet foods vary in moisture content. You must correct for the moisture so that you can determine the required level of crude protein for your pet food based upon its moisture guarantee. You can adjust the AAFCO Nutrient Profile level by doing the following:
If we tried to have a table for all possible moisture levels – for dry food, for canned food and for semi-moist food – the number of tables would be overwhelming. So, we make one table and then calculate to the appropriate level of moisture in the pet food.
Are claims such as "low fat" and "high protein" allowed on pet food labels?
AAFCO has approved a model feed law and regulations that the states are encouraged to adopt as their own state requirements. One of these regulations is the AAFCO Model Regulations for Pet Food and Specialty Pet Food. Pet foods are foods for dogs and cats, and specialty pet foods are foods for pets normally maintained in a cage or tank, such as hamsters, pet birds, and aquarium fish. About half of the states have adopted some version of these AAFCO pet food regulations.
The AAFCO Model Pet Food Regulations contain requirements for claims regarding calorie and fat content. Please check the section for Model Pet Food Regulation PF10. Descriptive terms can be found starting on page 141 of the 2010 Official Publication. In this section, Regulation PF10(a) covers the requirements for calorie claims stating “Light”, “Lite”, “Low Calorie”, “Less”, or “Reduced Calories”. Regulation PF10(b) covers the requirements for fat clams stating “Lean” and “Low Fat” and “Less” or “Reduced Fat”.
The AAFCO model regulations do not contain any specific requirements for other claims such as “high protein”, “low sodium”, etc., only that these claims should not be false or misleading to the consumer. A control official may be guided by the levels of the nutrients listed in the AAFCO Dog Food (and Cat Food) Nutrient Profiles starting on page 144 of the 2010 Official Publication. The levels in the Profiles are the minimum (and some maximum) levels for all essential nutrients required in dog food and cat food. Claims for carbohydrate levels in pet foods are discouraged since at this time there is no uniform method for determining carbohydrates.