Advanced Dog Nutrition Calculations

Most compare dog foods just based on brand and ingredients list – which honestly doesn’t tell you much about the food itself or if the food will meet your dog’s nutritional needs. Today we will be covering more advanced nutritional calculations that you can use to evaluate if a diet is appropriate for your dog, and if it meets their nutritional needs. 

In particular, we are going to cover: 1)  estimating the nutrient density of other declared nutrients within the diet on the guaranteed analysis, and then 2) based on the amount fed – are we meeting or exceeding our dog’s nutritional needs.

If you haven’t already read my article on basic dog nutrition calculations – starting there is likely a good idea.

Converting Guaranteed Analysis to Nutrient Density in Dog Food

I did cover this within my dog nutrition basics article for protein, fat and carbs – however other values such as calcium, phosphorus, EPA/DHA, etc are converted in different ways.

First – if you want to know if a value is within AAFCO nutrient profiles – you can convert this to g / 1000 kcals. Then you can compare that nutrient density to AAFCO Dog Nutrient Profiles Based on Caloric Content (on page 5 of the pdf).

CALCULATION:  [% on GA] / ( [ kcal/kg ] /10,000 ) = g/1000 kcals

Note that most pet food companies should be able to provide you with a typical analysis of their product that has the nutrients on a g/1000 kcal or g/100 kcal basis. This typical analysis number is not based on an estimated calculation but instead on laboratory testing of the finished product, thus it will be more accurate.

Example 1:

If we wanted to know the g/1000 kcal of calcium for the recipe above we would:

1.8% / ( 3900 kcals/kg / 10,000 ) = 4.6 g / 1000 kcals

Now if we compare this to AAFCO nutrient profiles we find that the acceptable range is: 1.25g – 6.25g /1000 kcal for adult dogs, 3 – 4.5g / 1000 kcals for the growth of large breed puppies, then 3 – 6.25g / 1000 kcals for smaller breed puppies.

Thus this recipe is potentially acceptable for both adult dogs and small-breed puppies for growth. But we can go further here to evaluate this.

Based on amount fed, is my dog getting too much or not enough?

This is the TRUE question we need to ask – because you can actually feed a diet created to AAFCO nutrient profiles and get too much or too little of certain nutrients for your dog based on the amount fed of the diet.

Also, depending on what your goals are we may want a certain dose of say – EPA & DHA – overall.

INFORMATION WE NEED: 1. How much is your dog eating in GRAMS per day of the dog food.

Probably the easiest way to obtain this information will be to simply weigh out your dog’s food. But if you are still in the stage of comparing diets, we may need to calculate or estimate the amount that we might feed based on either known or estimated caloric needs.

For this example I’m going to have two 25 lb dogs – one is an inactive adult dog, and the second is an active adult dog. (For this calculation head back to that “basics” calculation article.

  • Inactive Adult Dog is fed at RER x 1.4 = 607 kcals
  • Active Adult Dog is fed at RER x 2 = 866 kcals

Amount fed if 100% of the diet is the food given in the example (3900 kcal/kg):

  • Inactive Adult Dog: 607 kcals / 3.9 kcal/g = 155g
  • Active Adult Dog: 866 kcals / 3.9 kcal/g = 222g

So given the amount fed, how much is the dog consuming of Calcium?

CALCULATION: grams fed x % GA = g calcium (note that you need to divide the % by 100 before multiplying it by the grams because it’s a percentage value)

  • Inactive Adult Dog: 155g x 0.018 = 2.79g Calcium
  • Active Adult Dog: 222g x 0.018 = 3.99g Calcium

TIP: If you want a premade calculator, check out the Tufts Petfoodology Blog.

According to the NRC, is this amount of calcium appropriate for these dogs?

In order to calculate this we need to reference the NRC or the Nutritional Requirements for Dogs and Cats (at the end of this post I have an affiliate link to amazon if you’d like to purchase it and support me).

When using the NRC you use the column labeled Amt/kg BW^(0.75). There will be a number listed under minimal requirement, and recommended allowance for calcium listed for adult dogs.

In this case it is 0.059 for Minimal Requirement, and 0.13 for Recommended Allowance.

CALCULATION: [ given number ]  x ( [ wt in kgs ] ^(0.75) )

  • The Minimal Calcium Requirement for a 25 lb dog is: [ 0.059 ]  x ( [ (25/2.2)] ^(0.75) ) = 0.37g
  • The Recommended Allowance of Calcium for a 25 lb dog is: [ 0.13 ]  x ( [ (25/2.2)] ^(0.75) ) = 0.80g

There is no maximum for calcium listed for ADULT dogs within the NRC. When we compare our Inactive and Active dog’s amount consumed to the Recommended by the NRC, it’s rather large. These recipes contain well beyond minimal values. This is likely because this recipe is an “all life stage” recipe and is formulated for puppies as well, and puppies have both higher and stricter needs for calcium than adult dogs.

Example 2:

So let’s redo this problem again but with a medium-breed puppy that is 6 months of age, and weighs a total of 15 lbs. (Note this diet isn’t formulated for the growth of large breed puppies).

STEP 1: Caloric Needs

RER x 2 – 3 = 591 to 886 kcals per day

STEP 2: Amount to Feed

Kcals / day / (kcal/kg / 1000) = 151 to 227 grams per day

STEP 3: Calcium Consumed

% on GA x g fed = 2.7 to 4g calcium per day

STEP 4: NRC Calcium Needs

NRC # x ( (15/2.2)^0.75 )

  • Minimum 0.56 x ( (15/2.2)^0.75 ) = 2.36g calcium
  • Recommended 0.68 x ( (15/2.2)^0.75 ) = 2.87g calcium 
  • Maximum 1.25 x ( (15/2.2)^0.75 ) = 5.27g calcium

STEP 5: Comparison – Is this diet appropriate?

For the lower amount of calories consumed minimum calcium needs are met, but not recommended calcium needs according to the NRC.

On that note at the higher amount of calories consumed both minimum and recommended amounts are met. 

Note that recommended amount of calcium for large breed dogs is the same as the recommended allowance (which is 3g / 1000 kcals), however, we do have reported cases of orthopedic abnormalities with diets slightly above the recommended amount ( > 3.6g / 1000 kcals). Current AAFCO recommendations are to keep diets for large breed puppies below 4.6g/ 1000 kcals.

The NRC vs. AAFCO – Quick Summary

As I discussed there is an NRC created for Dogs and Cats. The NRC is what both AAFCO and FEDIAF nutritional profiles are based on. The NRC is a combination of thousands of research studies done on canine and feline nutrition, reviewed by experts, then presented to summarize what we currently know regarding Canine and Feline Nutrition.

Basically what AAFCO has done is adapted the NRC to fit typical nutritional profiles for dogs when manufactured as mass-scale. They try to account for nutrient losses during storage and nutrient digestibility. So when we go to evaluate pet foods to if they are personally appropriate for our dog’s nutritional needs on a more advanced level we not only look AAFCO nutrient profiles, but we can use the NRC to further evaluate the diet to if it’s appropriate based on amount fed.

Affiliate Link Purchase:

The link is an Amazon Affiliate Link and I will make a small commission if you use it to purchase this book. 

Since I use the NRC in order to make sure I am meeting or exceeding needs in both my homemade recipes and during consultations for key nutrients I do have an excel spreadsheet calculator that I have created to make these calculations easier. If this is something you are interested in message me and I can create it as a product download similar to my quick calculator on my previous article.

About the Author: Nikki is a Registered Veterinary Technician (Veterinary Nurse) and Dog Mom with over a decade of experience with dogs and cats. Since graduation from college (BS Biology, Dip. Animal Nutrition, AS Animal Science) she has adopted two mixed breed dogs – Ranger and Ash, and has focused her time learning about pet food and nutrition.

Nikki shares information on a range of dog nutrition topics: from how to create a homemade complete and balanced dog food recipes, to how to choose a dog food. Nikki strives to give dog parents the information they need in order to make the best nutrition decisions for their pup!

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