Table 5.
Comparison of measured ME with ME calculated using Atwater and modified Atwater equations, and resulting caloric surplus per day for 3 experimental diets differing in perceived glycemic response (PGR) fed to cats.
| Name | HighPGR | MediumPGR | LowPGR |
|---|---|---|---|
| Measured ME, kcal/kg as fed | 4259 a | 4574 b | 4787 c |
| Calculated ME, kcal/kg as fed | |||
| Modified Atwater 1 | 3752 | 4081 | 4137 |
| Traditional Atwater 2 NRC 3 |
4176 3778 |
4505 4301 |
4565 4413 |
| Calorie surplus per day (kcal/day) | |||
| Modified Atwater | 21.7 | 22.2 | 29.3 |
| Traditional Atwater NRC |
3.6 21.1 |
3.1 12.1 |
10 16.4 |
| Calorie surplus per day, % | |||
| Modified Atwater | 11.9 | 10.8 | 13.6 |
| Traditional Atwater NRC |
2.0 11.3 |
1.5 6.0 |
4.6 7.8 |
a–c Within a row, means without a common superscript differ (p < 0.05). 1 Calculated with modified Atwater equation (AAFCO, 1997): ME (kcal/kg) = 10 × (3.5 × Crude Protein % + 8.5 × Crude Fat % + 3.5 × Nitrogen-Free Extract %). 2 Calculated with traditional Atwater equation (Atwater, 1902): ME (kcal/kg) = 10 × (4 × Crude Protein % + 9 × Crude Fat % + 4 × Nitrogen-Free Extract %). 3 Calculated using the NRC predictive equations (NRC, 2006): Step 1: GE (kcal) = (5.7 × g protein) + (9.4 × g fat) + 4.1 × (g NFE + g fiber); Step 2: Percentage energy digestibility = 87.9 − (0.88 × percentage crude fiber in dry matter); Step 3: DE (kcal/g) = (GE × percentage energy digestibility/100); Step 4: ME (kcal/g) = DE − (0.77 × g protein).