To predict the apparent total tract digestibility (ATTD) of crude protein (CP) in
dogs we developed an
in vitro
system using an
in
vitro
digestion method and a statistical analysis. The experimental
diets used chicken meat powder as the protein source, with CP levels of 20%
(22.01%, analyzed CP value as dry-based), 30% (31.35%, analyzed CP value as
dry-based), and 40% (41.34%, analyzed CP value as dry-based). To simulate
in vivo
digestive processes a static
in
vitro
digestion was performed in two steps; stomach and small
intestine. To analyze ATTD the total fecal samples were collected in eight
neutered beagle dogs during the experimental period. CP digestibility was
calculated by measuring CP levels in dog food,
in vitro
undigested fraction, and dog feces. In result, CP digestibility at both
in vivo
and
in vitro
was increased with
increasing dietary CP levels. To estimate
in vivo
digestibility
the co-relation of
in vivo
ATTD and
in vitro
digestibility was investigated statistically and a regression equation was
developed to predict the CP ATTD (% = 2.5405 ×
in vitro
CP digestibility (%) + 151.8). The regression equation was evaluated its
feasibility by using a commercial diet. The predicted CP digestibility which was
calculated by the regression equation showed high index of similarity (100.16%)
with that of
in vivo
in dogs. With that, it would be a feasible
non-animal method to predict
in vivo
CP digestibility by using
in vitro
digestion method and the proposed linear
regression equation in adult dogs.