Heating and Soaking Influence in Vitro Hindgut Fermentation of Tropical Legume Grains in Pigs

The effects of different thermal (raw versus autoclaving or boiling for 5 and 20 min) and soaking (with or without) treatments on the in vitro hindgut fermentation in pigs of undigested residue collected after in vitro foregut digestion of tropical legumes’ grains (Canavalia brasiliensis; Lablab purpureus; pink, red and white Vigna unguiculata) were investigated. The undigested residue was fermented with a pig fecal inoculum to determine fermentability, gas, and short-chain fatty acid (SCFA) productions. Soaked raw legumes increased the production of SCFAs (e.g., butyric acid) and fermentability, while autoclaving reduced them. The productions of butyric acid and energy derived from SCFAs differed between legumes, with canavalia and lablab having the lowest and highest values, respectively. SCFAs and energy productions were highly related to the predicted nutrients entering the hindgut. In conclusion, different heating and soaking treatments can be applied to legumes to modulate the production of target SCFAs.