The effect of texturized vegetable protein containing soy carbohydrate on oroileal transit of chromic oxide in cannulated dogs

Texturized vegetable protein (TVP) from soy is widely used in dog foods but contains indigestible carbohydrate, which may affect intestinal transit. T his study was conducted to determine whether TVP affects oroileal transit o f the marker chromic oxide (Cr2O3). Four canned diets with Cr2O3 added were fed to eight cannulated mixed-breed dogs in a Latin-square design. The fou r diets contained reciprocal proportions of protein from TVP (0 to 57%) and from beef (100 to 43%). Ileal effluent was collected during wk 3 of each d iet period, prececal apparent digestibility was measured on d 1 to 3 (eight dogs), and rate of appearance of Cr2O3 and chyme was measured on d 4 (six dogs). There was a postprandial delay before any chyme or Cr2O3 was collect ed, but from 2 to 8 h postprandially the rate of excretion was almost const ant (approximately 11%/h). As TVP increased, mean prececal digestibility of protein and carbohydrate decreased from 77 to 71% and from 80 to 62%, resp ectively. Chyme excretion from 2 to 8 h postprandially increased from 5.8 t o 8.3 g DM/h (P < .0001) as TVP increased but times for transit of Cr2O3 an d appearance of chyme (as percentage total collected/hour) did not change. Mean times to first appearance and 15, 50, and 95% excretion were 76, 160, 347, and 707 min for Cr2O3 and 60, 147, 338, and 712 min for chyme, respect ively. Mean Cr2O3 recovery was 93%. In conclusion, small intestinal transit of Cr2O3 was unaffected by increasing dietary TVP despite marked changes i n carbohydrate digestibility.