Table 3. Evaluation of regression equations for predicting CP of ATTD in adult dogs

Items	Commercial diet1) (%)
In vitro CP digestibility	92.82 ± 0.09
Predicted in vivo CP digestibility (P)2)	84.00 ± 0.23
Analyzed in vivo CP digestibility (A)3)	83.87 ± 0.65
Index of similarity4)	100.16

The commercial diet used was a chicken- and rice-based adult dog diet (CP, 28.02%; analyzed as a dry-based value).
Predicted in vivo CP digestibility value was calculated by applying the in vitro CP digestibility value to the equation for predicting in vivo CP digestibility.
The in vivo CP digestibility value was evaluated for ATTD of the commercial diet in beagle dogs (n = 9). Values are expressed as the mean and SEM.
The index of similarity of CP digestibility was calculated as (P) / (A) × 100.
CP, crude protein; ATTD, apparent total tract digestibility.