Calculating metabolisable energy (ME) for pet food: methods and pitfalls
Every nutrient in a pet food is judged against its energy content, so the calorie number is the foundation of the whole formula. This is how our team calculates metabolisable energy — and why we analyse before we calculate.
- Nutrient profiles are set per 1000 kcal of metabolisable energy (ME), so energy errors distort every nutrient check.
- Markets specify different calculation methods; we use the one each market requires.
- Standard equations can misjudge modern foods — errors of 8–12% have been reported for wet foods.
- We calculate energy from analysed values; we do not measure ME in feeding studies or by bomb calorimetry.
01Why energy comes first
AAFCO and FEDIAF express nutrient requirements per 1000 kcal of metabolisable energy as well as per kilogram of dry matter 1,2. A recipe that looks balanced on a weight basis can fall short once energy is taken into account — a denser, higher-fat food is fed in smaller amounts, so every nutrient has to be more concentrated. That is why our formulation starts with an accurate energy value.
02The calculation methods
| Method | How it works | Where it is used |
|---|---|---|
| Modified Atwater factors | 3.5 kcal/g for protein and carbohydrate, 8.5 kcal/g for fat, applied to the guaranteed or analysed values | US calorie statements (AAFCO) |
| NRC 2006 equations | Gross energy from protein, fat and carbohydrate; digestibility estimated from crude fibre; then urinary losses subtracted | Recommended by FEDIAF for Europe and the UK 2 |
| Feeding studies | Energy measured from intake and faecal and urinary losses | Not offered by Guires Pet Nutrition Lab — we calculate |
03Why we analyse before we calculate
Every equation is only as good as the numbers put into it. Book values for ingredients vary with source and season, and processing changes moisture and digestibility. Published comparisons show that standard prediction equations can misjudge modern foods — one analysis of 451 foods reported errors of about 8–12% for wet foods 3,4.
So we calculate energy from analysed proximate values (moisture, protein, fat, fibre, ash) on representative samples, then check the nutrient balance again at the final energy value.
04Our step-by-step process
How we do it
- Agree the target markets and the energy method each requires.
- Analyse or source reliable proximate values for each raw material.
- Calculate ME for the recipe and balance nutrients per 1000 kcal.
- Analyse the prototype and recalculate energy from real values.
- Set the calorie statement and feeding guide from the final figure.
- Recheck after any change of supplier, recipe or process.
The energy value is the foundation of the formula. Calculate it from analysed values, with the method each market requires.
05Questions brands ask
Why not use book values?
Ingredient values vary with source and processing, and standard equations can already misjudge modern foods — errors compound.
Do you measure ME in feeding studies?
No. We calculate energy using the method each market specifies, from analysed values.
Sources
- AAFCO dog and cat food nutrient profiles. Source ↗
- FEDIAF (2025). Nutritional Guidelines for complete and complementary pet food. Source ↗
- Hall JA et al. (2013). PLoS ONE. Source ↗
- Vendramini THA et al. (2025). Animals 15(10):1477. Source ↗
Evidence reviewed by the Guires Pet Nutrition Lab scientific team. This article is general information for product developers and is not legal or veterinary advice.
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Guires Pet Nutrition Lab. (2026, September 29). Calculating metabolisable energy (ME) for pet food: methods and pitfalls. Guires Pet Nutrition Lab Insights. https://www.petnutritionlab.com/insights/energy-calculation
Guires Pet Nutrition Lab. “Calculating metabolisable energy (ME) for pet food: methods and pitfalls.” Guires Pet Nutrition Lab Insights, 29 Sep. 2026, www.petnutritionlab.com/insights/energy-calculation. Accessed [date].
Guires Pet Nutrition Lab (2026) Calculating metabolisable energy (ME) for pet food: methods and pitfalls. Available at: https://www.petnutritionlab.com/insights/energy-calculation (Accessed: [date accessed]).
Guires Pet Nutrition Lab. “Calculating metabolisable energy (ME) for pet food: methods and pitfalls.” Guires Pet Nutrition Lab Insights. September 29, 2026. https://www.petnutritionlab.com/insights/energy-calculation.
Guires Pet Nutrition Lab, ‘Calculating metabolisable energy (ME) for pet food: methods and pitfalls’, Guires Pet Nutrition Lab Insights, 29 September 2026, <https://www.petnutritionlab.com/insights/energy-calculation>, accessed [date accessed].
Guires Pet Nutrition Lab. Calculating metabolisable energy (ME) for pet food: methods and pitfalls [Internet]. Guires Pet Nutrition Lab Insights; 2026 Sep 29 [cited [date]]. Available from: https://www.petnutritionlab.com/insights/energy-calculation
Guires Pet Nutrition Lab, “Calculating metabolisable energy (ME) for pet food: methods and pitfalls,” Guires Pet Nutrition Lab Insights, Sep. 29, 2026. [Online]. Available: https://www.petnutritionlab.com/insights/energy-calculation
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author = {{Guires Pet Nutrition Lab}},
title = {{Calculating metabolisable energy (ME) for pet food: methods and pitfalls}},
year = {2026},
month = sep,
howpublished = {\url{https://www.petnutritionlab.com/insights/energy-calculation}},
note = {Guires Pet Nutrition Lab Insights}
}
This article summarises published evidence for product developers. Cite the original sources above for specific findings, and do not reproduce this article as your own work.
Need an accurate calorie statement?
We calculate energy from analysed values and prepare feeding guides for each market.