MW, ME and DMB Requirements and What They Mean
This article covers the following questions:
- Why it’s important to follow the feeding guidelines listed on your commercial food packaging (AAFCO, FEDIAF)
- Why NRC ME (requirement per 1000kcal) or NRC DMB (dry matter basis) is not appropriate for most dogs
- What NRC energy multipliers mean in terms for activity and energy for the average dog and cat
Important Definitions
Metabolic Weight
This is the standardized weight of an animal.
- For dogs, MW = weight in kilograms ^ 0.75
- For cats, MW = weight in kilograms ^ 0.67
Energy Multiplier
NRC uses “energy multipliers” to determine how many calories an animal should eat per day, based on the pet’s weight.
- 70-90 – low: appropriate for dogs who are fairly sedentary, with 1-2x 15-60 minute, non-arduous walks per day. (Senior dogs may be even lower)
- 90-110 – moderate: appropriate for dogs who are generally active, with 1-2x 45+ minute arduous (hiking, running) walks per day
- 110-130 – high: appropriate for working dogs. Dogs that participate in sports, young adult dogs *
- 130 – NRC Standard: this is what NRC uses as the standard energy multiplier for all nutrient requirements
* young adult dogs (1-3 years depending on breed) typically have higher caloric needs even after reaching adult weight and active bone growth has slowed/stopped.
* Sport dogs may need more than 130 during active seasons/days.
The energy multipliers listed above are for general purposes and an animal’s caloric intake can be affected by breed, individual rate of metabolism, genetics, activity.
- 55-70 – low/moderate: appropriate for indoor pet cats who are fairly sedentary, with short to moderate bursts of energy. This range would be appropriate for most indoor pet cats. (Inactive cats with weight loss goals or seniors may fall below this category)
- 70-100 – high: appropriate for young adult cats *, exotic breeds, or highly active/outdoor cats
100 – NRC Standard: this is what NRC uses as the standard energy multiplier for all nutrient requirements
* young adult cats (1-2 years depending on breed) typically have higher caloric needs even after reaching adult weight and active bone growth has slowed/stopped.
The energy multipliers listed above are for general purposes and an animal’s caloric intake can be affected by breed, individual rate of metabolism, genetics, activity.
Caloric (energy) Intake
This is the amount of calories the animal should eat. The best way to determine a pet’s caloric intake is to assess their current diet. This can be estimated using MW and energy multiplier (MW x energy multiplier)
Caloric Density
This is how many calories a food contains, based on the weight of the food. This is typically measured on an “dry matter” basis (moisture excluded). A couple of examples:
- Raw ground beef 10% is 176kcal per 100g with 69.5g water. This would mean it’s 5.8kcal/g DM. Math: 176 kcal / (100g – 69.5 g)
- A generic kibble is 4000 kcal per kg with 12% moisture. This would mean it’s 4.5 kcal/g DM. Math: 4000kcal / 88%
NRC Requirements
When looking at NRC requirements, there’s three different ways the requirements are presented – ME, MW and DMB. When used correctly, all three sets of requirements result in the same nutritional requirements for the animal.
The reason the requirements are presented in three different ways so that it’s possible to assess the nutritional adequacy of the diet based on different types of analyses. For example, if formulating for an individual pet, calculating the requirements based on that single pet’s weight may make sense, but when formulating for a wide range of pets (commercial formulations), it’s much easier to calculate the requirements based caloric or dry matter basis of the food rather than all the individual pets who may be eating that food.
MW Requirements
This requirement is presented as x amount of nutrient per MW. To calculate your pet’s requirements, multiply the requirement by your pet’s MW. For dogs: (your pet’s weight in kilograms) ^ 0.75. For cats: (your pet’s weight in kilograms) ^0.67.
This is the simplest way to calculate your pet’s nutritional requirements, as there is no need to adjust for the low energy intake or the energy density of the food. For pet owners, this is how I recommend calculating your pet’s nutritional requirements. For commercial or large pack/clowder formulations however, this is not a practical way to formulate.
NRC requirement for protein for adult dogs is 3.28g/MW. A 70lb dog’s protein requirement would be:
70lbs = 31.8kg
MW: 31.8kg ^ 0.75 = 13.4
Dog’s Protein requirement: MW requirement x Dog’s MW = 13.4 x 3.28g = 44g protein per day
ME Requirements
This requirement is based on the caloric intake of the animal, assuming standard NRC energy multipliers (130 for dogs, 100 for cats). ME requirements are presented as x amount of nutrient per 1000kcal of food. To calculate the nutritional requirements, multiply the requirement by food’s caloric content.
The key caveat here is that ME requirements should only be used for animals with the NRC standard energy multipliers.
The NRC book states regarding the ME requirements:
- “For dogs with an unusually low energy intake (below the suggested requirement), the nutrient concentrations (Amt/1000kcal) may not be adequate. These animals should be fed the nutrients amounts shown in the column Amt/kg BW ^ 0.75”
- “For cats with an unusually low energy intake (below the suggested requirement), the nutrient concentrations (Amt/1000kcal) may not be adequate. These animals should be fed the nutrients amounts shown in the column Amt/kg BW ^ 0.67”
To put it into context, these are very high caloric intakes for the typical pet dog or cat. The average dog or cat would quickly gain weight if eating this many calories per day. See typical energy multipliers in the Definitions section of this page (above).
NRC requirement for protein for adult dogs is 25g/1000kcal. For a 70lb dog, this would come out to:
MW: 13.4
Dog’s caloric intake: energy multiplier x MW = 130 x 13.4 = 1740kcal
Dog’s protein requirement: caloric intake x ME requirement = 1740kcal x 25g/1000kcal = 44g protein per day
This gives us the same result as calculating the dog’s requirement by the MW set of requirements.
What if your pet has lower caloric intake than what the ME requirement require? Then you should use the MW requirements instead.
Alternatively, you can adjust the ME requirements to reflect the pet’s true energy multiplier.
For example, if the dog you are formulating for a has an energy multiplier of “80”, you would multiply the ME nutrient requirement by 130/80 = 1.625. This mean that all nutrients must be increased by 62.5% in order to make the food nutritionally adequate for that dog.
Let’s take the example of our 70lb dog from before. This dog currently eats 1300kcal per day, and is maintaining a healthy weight. We can use the same equation to determine caloric intake to determine the pet’s energy multiplier.
MW = 13.4
Caloric intake: MW x energy multiplier
1300 = 13.4 x energy multiplier
Dog’s true energy multiplier: 1300 / 13.4 = 97
Dog’s protein requirement: ME requirement x caloric intake x (NRC standard energy multiplier / dog’s true energy multiplier) = 25g/1000kcal x 1300kcal x 130/97 = 44g protein per day
This gives us the same number as calculating the pet’s nutrient requirement by MW. It also gives us the same nutrient requirements as calculating the pet’s nutrient requirements by ME at the correct (130) energy multiplier.
DM Requirements
This nutrient requirement is based on the dry matter weight of the food. To calculate the nutritional requirements, multiply the requirement by food’s dry matter weight.
This requirement has two key caveats:
- The food must be around 4kcal/g DM. If the food has a significantly greater or lower caloric density (kcal/g DM), you need to adjust the requirement to reflect that difference.
- Like the ME requirements, this is only appropriate for animals eating at the NRC standard energy multiplier, 130 for dogs and 100 for cats
The NRC book states regarding the DM requirements:
- “The values for Amt/kg DM have been calculated assuming a dietary energy density of 4000kcal ME/kg, If the energy density of the diet is not 4000kcal ME/kg, then to calculate the Amt/kg DM for each nutrient, multiply the value for the nutrient in the column labeled Amt/kg DM by the energy density of the pet food (in kcal ME/kg) and divide by 4000).
DM requirement for protein is 100g/kg DM. For a food that is 4000kcal per kg and a 70lb dog with energy multiplier “130”, the dog’s requirement would be:
MW: 13.4
Dog’s caloric intake = energy multiplier x MW = 130 x 13.4 = 1740kcal
Dog’s food intake: dog’s caloric intake / food’s caloric density = 1740kcal / 4000kcal/kg = 0.435kg food
Dog’s protein requirement: dog’s DM food intake x DM requirement = 0.435kg x 100g/kg = 44g protein
This ends up giving us the same requirement as the dog’s MW and ME requirements.
What if the food has a greater caloric density than 4kcal/g?
Most raw and cooked foods are around 4.5-5kcal/g. If formulating a raw or cooked diet and using DMB requirements, you need to adjust the requirements to reflect the higher caloric density. You can do this by multiplying the requirement by (true caloric density / 4).
Continuing from example 4, if the food is now 4500kcal per kg DM, and a 70lb dog has the energy multiplier “130”, the dog’s requirement would be:
MW: 13.4
Dog’s caloric intake = energy multiplier x MW = 130 x 13.4 = 1740kcal
Food’s caloric density per gram DM: 4500kcal/kg = 4.5kcal/g
Dog’s food intake: dog’s caloric intake / food’s caloric density = 1740kcal / 4500kcal/kg = 0.387kg food
Dog’s protein requirement: dog’s DM food intake x DM requirement x (true caloric density / 4) = 0.387kg x 100g/kg x 4.5/4 = 44g protein per day
This would give us the same protein requirement as if the food has the correct caloric density.
What if the dog has a lower energy multiplier? We would make the same adjustment as we would for ME requirements, and multiply the requirement by: NRC assumed energy multiplier (130 for dogs, 100 for cats) / animal’s current energy multiplier
Continuing from example 5, for a food that is 4500kcal per kg DM but for a 70lb dog with an energy multiplier of “97”, the dog’s requirement would be:
Dog’s caloric intake: 1300kcal
Food’s caloric density per gram DM: 4.5kcal/g
Dog’s food intake: dog’s caloric intake / food’s caloric density = 1300kcal / 4500kcal/g = 0.289kg food
Dog’s protein requirement: dog’s DM food intake x DM requirement x (true caloric density / 4) = 0.289kg food x 100g/kcal x 4.5/4 x 130/97 = 44g protein
This gives us the same number as calculating the pet’s nutrient requirement by MW. It also gives us the same nutrient requirements as calculating the pet’s nutrient requirements by ME at the correct (130) energy multiplier or DMB at the correct energy multiplier (130) and caloric density of the food (4kcal/g).
Sport Dogs and High Calories
What if your dog needs more calories than the “130” energy multiplier indicates?
For sport dogs during their active seasons, the necessary caloric intake can be much higher than 130 x MW. In cases like this, ME requirements should be used to ensure that you are meeting the nutritional needs of higher energy intake. This means that MW requirements would NOT be sufficient. Using ME or DMB requirements will help you account for the additional nutrients needed when dogs are expending a lot of energy.
Let’s take a 70lb hunting dog who needs 3000kcal per day. NRC requirements for protein for adult dogs is 3.28g/MW, or 25g/1000kcal.
If using MW, this dog’s protein requirement would be:
MW: 13.4
Dog’s Protein requirement: MW requirement x Dog’s MW = 13.4 x 3.28g = 44g protein per day
If using ME, this dog’s protein requirement would be:
Dog’s caloric intake: 3000kcal
Dog’s protein requirement: caloric intake x ME requirement = 3000kcal x 25g/1000kcal = 75g protein per day
ME requirements gives us the higher, more accurate, protein requirement in this case.
NRC Requirements: Summary
So which NRC requirement is “the best”?
Nutritionally speaking, none, or rather, all! The NRC requirements are all the same requirements, presented in different formats. What is “best” practically speaking is going to depend on the whether or not you’re formulating for a personal or individual pet, or if you are formulating for a generic profile, and the expected energy intake of the pet.
- For personal or individual pets with standard energy intake and below, use MW requirements or adjusted ME requirements
- For personal or individual pets over standard energy intake, use ME requirements (with or without adjustment)
- For formulations made for a generic profile or multiple pets, use ME requirements for fresh food (raw or cooked)
Practical Applications
So looking at these different requirements, what does it mean practically for formulators?
Formulating with AAFCO and FEDIAF
AAFCO and FEDIAF requirements are presented only in ME and DM, which reflects the commercial nature goal for these standards. Nonetheless, the requirements are still presented for 1-2 energy levels, and will need to be adjusted if the pet needs a lower caloric intake.
- AAFCO presents requirements ME and DM for only 1 assumed energy intake (similar to NRC assumed energy intake)
- FEDIAF presents requirements ME and DM for 2 energy intakes (95 and 110 for dogs, and 75 and 100 for cats)
Though FEDIAF provides 2 sets of requirements for the two energy multipliers, they are still the same ME requirement, adjusted for energy intake differences (ie the same process as adjusting NRC ME requirements). This means that you could adjust from either requirement as a starting point, and get the same end result (for example, adjusting for energy intake of 80xMW from the 95xMW requirement (* 95/80) or from the 110xMW (* 110/80) will get you the same result)
NOTE: This does NOT mean all AAFCO/FEDIAF kibbles (or other commercial formulations) are formulated for dogs and cats with standard energy intake. A good formulation will account for the typical animal’s energy intake for that marketed/targeted line of food.
Following Feeding Guidelines
When feeding commercial foods that have been formulated using any scientific standard (NRC, AAFCO, FEDIAF), it’s important to follow the feeding guidelines as it’s listed on the bag or label. This is because the formulation/food is ONLY appropriate for the energy range it’s formulated for.
Commercial foods are formulated to a generic range of energy multipliers. This is reflected in the feeding chart, which lists how much of the food your dog needs to eat in order to receive enough nutrients from the food. In the same way that using as-is ME requirements for dogs with low energy intakes would provide inadequate nutrition, feeding less than the what’s recommended by the manufacturer results in less nutrients in the bowl than what your pet needs.
If your pet needs to lose weight, it’s important to switch your pet to a weight-loss formulation, instead of simply lowering the amount of food you’re feeding your pet. While reducing the amount of the current food works for restricting calories, it also restricts the nutrients your pet needs at the current size.
Formulation Tools
RFN SHEET
- The RFN Sheet formulates NRC dog requirements by MW and cat requirements by ME. AAFCO and FEDIAF are DM requirements
- NRC dog requirements only need adjusting if your dog needs >130xMW *
- NRC cat requirements need adjusting if your cat needs <100xMW *.
- AAFCO and FEDIAF requirements need adjusting for energy density and energy intake *
* RFN v4 will update requirements so it no longer needs adjusting
PDD
- PDD calculates dog and cat requirements by ME (standard)
- Dog requirements need adjusting if your dog needs < 130xMW
- Cat requirements need adjusting if your cat needs < 100xMW
- If your pet needs less than the NRC standard energy intake, you can see the adjusted or correct requirement by setting the pet’s profile to the NRC standard energy level. You would need to manually formulate the recipe to meet the animal’s actual (lower) energy intake
Cronometer
- Requirements need to be manually entered into Cronometer. This means that you will need to calculate the requirements yourself and enter each one manually. Follow guidelines above for MW vs ME requirements and enter as appropriate.