Influence of sulfur on the fermentation characteristics of corn distiller's dried grains with solubles in in vitro culture
2017
Liwen He | Hao Wu | Wanbao Chen | Qingxiang Meng | Zhenming Zhou
The effects of sulfur on the fermentation characteristics of corn distiller's dried grains with solubles (DDGS) in in vitro culture were investigated. Samples (DDGS) were analyzed for nutrient values and then two independent in vitro experiments were conducted to study the effects of various sulfur sources (Na2S, Na2S2O4, Na2SO3, and Na2SO4) and different sulfur levels (0.346, 0.692, and 1.038%) on the fermentation characteristics of DDGS. Based on sampling and chemical composition analysis, there existed a great variation in the concentrations of sulfur and proximate nutrients of DDGS. In Experiment 1, sulfur source showed a significant (P < 0.01) effect on the gas production parameters (asymptotic gas production (b) and gas production rate (c)) and gas production of DDGS - sulfur from Na2SO4 and Na2S produced more (P < 0.01) gas within 48 h with a faster gas production rate as well as higher digestibilities (dry matter degradability and organic matter digestibility) and more energy supplies (metabolizable energy), net energy for maintenance and gain, and net energy for gain than sulfur from Na2SO3 and Na2S2O4. Neither ammonia-nitrogen (NH3-N) concentration nor volatile fatty acids (VFA) profile (total VFA and individual VFA proportion) were affected by sulfur source (P > 0.05). In Experiment 2, no significant (P > 0.05) effect on the fermentation characteristics of DDGS with increasing sulfur content was found. The collective findings suggest that regular chemical analyses are necessary to make full use of DDGS, and that the valence state of sulfur in DDGS exerts an effect on its in vitro fermentation characteristics and there appears no dose-related effect of sulfur on the fermentation of DDGS in a short-term in vitro culture.
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