Energy Coefficients Explained
NRC 2006 uses formulas based on metabolic body weight (BW0.75) to calculate energy requirements. Different lifestages use different base coefficients, and some lifestages add additional energy terms for growth, pregnancy, or lactation. The resulting daily energy requirement determines how all nutrient requirements scale.
How It Works
- 1
Calculate Metabolic Body Weight
Metabolic weight = (body weight in kg)0.75. This exponent accounts for the relationship between body size and metabolic rate.
- 2
Apply Base Coefficient
For adults, ME = 70 × BW0.75 × activity multiplier (RER scaled by activity level). For non-adult lifestages, NRC uses fixed coefficients: 130 for puppies and pregnant dogs, 145 for lactating dogs.
- 3
Apply Lifestage-Specific Modifiers
Puppies use a multiplicative growth factor based on their current weight relative to expected adult weight. Pregnant dogs add energy per kg body weight. Lactating dogs add energy based on milk production.
- 4
Scale Nutrient Requirements
NRC expresses all nutrient requirements per 1,000 kcal. Your dog's daily energy requirement determines how these values scale.
NRC 2006 Energy Formulas
| Lifestage | Formula | Source |
|---|---|---|
| Adult | 70 × BW0.75 × activity multiplier | NRC Table 15-2 |
| Puppy (growing) | 130 × BW0.75 × 3.2 × [e−0.87p − 0.1] | NRC Table 15-2 |
| Pregnant | 130 × BW0.75 + 26 × BW | NRC Table 15-6 |
| Lactating | 145 × BW0.75 + milk energy | NRC Table 15-7 |
Note: For adults, NRC 2006 publishes 130 × BW0.75 as the standard maintenance formula. This is equivalent to RER (70 × BW0.75) × 1.86 activity multiplier - close to the 2.0× average for active dogs. RawPawIQ uses user-adjustable activity multipliers so results reflect your dog's actual activity level rather than a fixed coefficient. For puppies, pregnant, and lactating dogs, the NRC lifestage formulas are used directly and activity level does not apply.
In the puppy formula, p = current weight ÷ expected adult weight. The growth factor decreases as the puppy approaches adult size. Milk energy depends on litter size and lactation week.
Why This Exists
A 10kg puppy and a 10kg adult dog have the same metabolic body weight, but vastly different energy needs. The puppy is building bone, muscle, and organ tissue while the adult only needs to maintain existing tissue. The NRC formulas account for these differences by adding growth, pregnancy, or lactation energy to the base maintenance requirement.
Common Misinterpretations
"Puppies need 2-3× adult calories"
The actual multiplier varies by the puppy's current and expected mature weight. The NRC formula uses growth curves, not fixed multipliers, so results differ between a Chihuahua puppy and a Great Dane puppy.
"130 is the only coefficient used"
Lactating dogs use 145 as the base coefficient (NRC Table 15-7). This higher baseline reflects the metabolic demands of milk production.
"Activity level is included in these formulas"
NRC formulas cover maintenance, growth, and reproduction. Activity adjustments are separate considerations that may increase energy needs above these baseline calculations.