Characterization of the in vitro digestion of starch and fermentation kinetics of dry sorghum grains soaked or rehydrated and ensiled to be used in pig nutrition

摘要

The effect of soaking and rehydration plus ensiling of different dry sorghum grains on indicators of pig digestion was evaluated using in vitro approaches. Five commercial paddocks of sorghum grains were harvested dry and subjected to different treatment conditions: dry ground (Dry, control), grain soaked for 24 h (SG), and rehydrated and ensiled for 21 days as whole grain (EWG) or ground grain (EGG). The level of tannins was lower in the treated sorghums than in the Dry sorghums (P 0.01), and in the ensiled grains the level of starch decreased (P 0.001). The treatments caused an increase in the potential digestion of starch, and the EGG treatment was the one with the highest value for this variable (P 0.001). The predicted glycemic index (pGI) and hydrolysis index (HI) values were higher in the EGG treatment and intermediate in EWG treatment with respect to Dry and SG (P 0.001). In vitro digestion of DM was greater in the EGG treatment (P = 0.005), and EGG had the highest in vitro gas production rate (P = 0.022). Treatments produced changes in chemical composition and in characteristics of the starch, but the combination of the grinding, rehydration and ensiling was the one with the highest levels of digestibility.