Amino acid and fiber digestibility, intestinal bacterial profile, and enzyme activity in growing pigs fed dried distillers grains with solubles-based diets

Y. Yang,* E. Kiarie,* B. A. Slominski,* A. Brûlé-Babel† and C. M. Nyachoti*

The aim of this study was to determine ileal AA and fiber digestibility in new-generation dried distillers grains with solubles (DDGS) derived from wheat (wDDGS), a wheat-corn blend [wcDDGS, wheat and corn were fermented in a 7:3 wt/wt ratio], or corn (cDDGS) and to determine the effects of diets containing DDGS on gut bacteria and bacterial and digestive enzyme activities. Experimental diets contained one of the DDGS samples as the sole source of protein, and a low protein diet (5% casein) was included to estimate basal endogenous ileal CP and AA losses. Chromic oxide (0.3%) was added as an indigestible marker to all diets. Twelve cannulated barrows with an initial BW of 20.2 ± 1.3 kg were allotted to the 4 experimental diets in a 2-period crossover design, which provided 6 observations per diet. Pigs were acclimatized to their diets for 5 d followed by a continuous 12-h digesta collection on d 6 and 7. Diet had no effect on the apparent ileal digestibility (AID) of CP (P = 0.58). The wDDGS diet generally had decreased (P < 0.05) AID of AA compared with the wcDDGS or cDDGS diet. Similarly, the values for standardized ileal digestibility of CP and most AA were smaller (P < 0.05) for the wDDGS diet compared with the other 2 DDGS diets. The Lys and Thr were the least digestible AA among the indispensable AA across the 3 DDGS samples. The digestibilities of nonstarch polysaccharides and NDF were not affected by diet (P = 0.80 and 0.40, respectively); however, the ileal digesta viscosity was greater (P < 0.05) for the wcDDGS diet than the wDDGS and cDDGS diets. The counts of Lactobacillus (P = 0.09) and Enterobacteriaceae (P = 0.05) were greater for the cDDGS diet compared with the other 2 diets. Accordingly, the cDDGS diet elicited a greater (P < 0.05) lactic acid concentration in digesta than the wDDGS diet. The activities of bacterial (P = 0.86 to 0.91) and digestive enzymes (P = 0.31 to 0.80) did not differ among the diets. The results indicate that the wDDGS had generally less protein and AA ileal digestibilities compared with the wcDDGS and cDDGS samples and that nonstarch polysaccharides and NDF digestibilities were similar among diets. Although diet influenced digesta bacterial counts, no effects were observed on the activities of bacterial and digestive enzymes.

Keywords: bacterial and digestive enzyme activity, digestibility, dried distillers grains with solubles, gut bacteria, pig