FEDIAF energy formulas

FEDIAF 2025 (Annex 7.2) provides a layered set of energy equations rather than a fixed count of formulas: (1) Gross energy (Table VII-5): crude protein 5.7 kcal/g, crude fat 9.4 kcal/g, NFE + crude fibre 4.1 kcal/g (23.8 / 39.3 / 17.1 kJ/g). (2) NRC 2006 predictive equations for prepared pet foods (basis of EN 16967): GE = 5.7 × %CP + 9.4 × %CF + 4.1 × (%NFE + %CFibre); energy digestibility = 91.2 − 1.43 × %CFibre DM (dogs) or 87.9 − 0.88 × %CFibre DM (cats); DE = GE × digestibility/100; ME = DE − 1.04 × %CP (dogs) or DE − 0.77 × %CP (cats) — with a caveat that the equation can underestimate energy density in dog foods above 8% crude fibre with highly fermentable NSP. (3) For products of vegetable or animal origin in their natural state and highly digestible specialty products: dogs ME = 4 × %CP + 9 × %CF + 4 × %NFE; cats ME = 4 × %CP + 8.5 × %CF + 4 × %NFE. (4) The modified Atwater method (3.5 / 8.5 / 3.5 kcal per g of CP / CF / NFE) — reviews (Calvez J et al. 2012a/b) found the NRC equations more accurate than modified Atwater for dry foods, and both moderately accurate for wet foods. (5) Feeding-trial determination (gold standard): ME = DE − energy lost in urine, using correction factors of 1.25 kcal/g digestible protein (dogs) and 0.86 kcal/g (cats) when urine is not collected. Unit conversions assume an energy density of 4.0 kcal (16.7 kJ) ME per g DM — i.e. a reference of 400 kcal/100 g DM — with foods of different density corrected proportionally.