Degradation and fermentation characteristics of wheat coproducts from flour milling in the pig intestine studied in vitro1

Use of wheat (Triticum aestivum) flour milling coproducts (WFM) in pig diets may ameliorate high feed cost. However, digestibility of WFM is lower than feed grains, and limited information exists about their fermentation characteristics. In vitro degradation and fermentation characteristics of 6 WFM samples (2 Shorts, 2 Millrun, middlings, and bran) with varying fiber and protein contents were studied. After a pepsin–pancreatin hydrolysis, WFM were incubated in a buffer solution with minerals and fresh pig feces as inoculum. Accumulated gas production was measured for 72 h and modeled. The VFA concentration was measured in the fermented solutions. The DM degradability during fermentation ranged from 31 to 52% and correlated negatively with ADF (r = –0.65; P < 0.01) and positively with CP (r = 0.50; P < 0.01) content of WFM. Total gas production ranged from 101 to 148 mL/g DM incubated and was negatively correlated with ADF and crude fiber (r = –0.70 and –0.59, respectively; P < 0.01). The VFA production ranged from 2.0 to 3.0 mmol/g and the fractional rate of degradation ranged from 0.08 to 0.11/h. In conclusion, fiber components were associated with degradability and fermentability of WFM. Therefore, treatments targeted to reduce the impact of fiber and protein may increase the digestibility and fermentability of wheat coproducts from flour milling.