Porcine in vitro digestion and fermentation characteristics of corn wet distillers’ grains and dried distillers grains with solubles without or with multi-enzyme

Abstract

Wet distillers grains (wet DG) and condensed distillers are co-products from ethanol plants, which are combined and dried into distillers grains with solubles (DDGS). Information is lacking on effects of producing DDGS from wet DG on response to fiber-degrading enzymes in terms of digestibility of DDGS for pigs. This study determined porcine in vitro digestion and fermentation characteristics of wet DG and DDGS without or with multi-enzyme that supplied 9600 U of xylanase, 1200 U of glucanase, 4000 U of cellulase, 480 U of mannanase, 5600 U of invertase, 40,000 U of protease, and 96,000 U of amylase/kilogram of feedstuff. Four gram samples were weighed into conical flasks (5 flasks per treatment) and hydrolyzed in 2 steps using pepsin and pancreatin. Subsequently, undigested residues were incubated in a buffer solution with minerals and fresh pig feces as inoculum. Gas production was measured for 72 h, and modeled to estimate kinetics of gas production. Concentration of volatile fatty acids (VFA) was measured in fermented solutions. On dry matter (DM) basis, the wet DG and DDGS contained 235.2 and 288.7 g/kg crude protein, and 62.5 and 109.9 g/kg ether extract, respectively. There was no interaction between feedstuff and multi-enzyme on any of the response criteria measured in this study. Coefficient of in vitro digestibility of DM (IVDDM) of wet DG (0.497) did not differ from that of DDGS (0.498). Multi-enzyme supplementation did not affect the IVDDM of wet DG or DDGS. Total gas production per unit weight of enzymatically unhydrolyzed residue for wet DG was greater (P<0.05) than that of DDGS (122.8 vs 108.9 mL/g DM). Multi-enzyme supplementation increased (P<0.05) the total gas production per unit weight of enzymatically unhydrolyzed residue for wet DG and DDGS by 4.94 and 10.33%, respectively. There was no effect of feedstuff or multi-enzyme on degradation rate and VFA production of enzymatically unhydrolyzed residue. In conclusion, the wet DG and DDGS were similar in IVDDM; however total gas production for enzymatically unhydrolyzed residue for wet DG was greater than that for DDGS, implying that wet DG is more fermentable than DDGS. The multi-enzyme product used in the current study can improve fermentability of wet DG and DDGS for pigs. Feedstuff and multi-enzyme did not interact on any response criteria measured this study, implying that the drying of wet DG into DDGS did not influence the effect of the multi-enzyme on digestibility of DDGS for pigs.