Impact of water addition, germination, ensiling and their association on sorghum grain nutritive value

The objective of this study was to evaluate the effects of water addition, germination, ensiling and/or their association with respect to chemical composition and nutritive value of dry sorghum grain. Five commercial paddocks of sorghum grain were harvested dry and evaluated for chemical composition, digestion site and in vitro gas production under six treatment conditions: dry ground (dry), soaked for 24 h (SG), germinated for 5 days (G), germinated for 5 days and then ensiled for 21 days (G&E), ensiled for 21 days as whole grain (EWG) or ensiled for 21 days as ground grain (EGG). Soaked, EWG and G&E treatments led to a lower starch content compared to dry grains (P<0.05). Reconstituted and ensiled treatments (either as whole or ground grain) decreased the tannin concentration compared to dry grains (P<0.05). The dry matter (DM) digestion site and total tract digestibility were similar among dry grains, G and EWG. However, compared to these treatments, G&E and EGG increased ruminal and total DM digestibility (P<0.05). Total tract DM digestibility did not differ between SG and dry grains; however, SG affected DM digestion site (P<0.05). Starch digestion site and total tract digestibility were similar between dry grains and EGG. Although G&E and EWG had similar total starch digestibility in comparison with dry grains, these treatments affected the digestion site (P<0.05). Soaked and G treatments reduced total tract digestibility and changed the starch digestion site compared to dry grains (P<0.05). In vitro fermentation of dry grains was similar to SG and EWG. Although the total in vitro gas production was less for G&E and EGG than dry grains (P<0.05), these treatments fermented more rapidly than dry grains (P<0.05). The soaking, the germination process, or the ensiling of whole sorghum grain as sole factors, produced changes in the chemical composition but did not improve the nutritive value of sorghum grain. However, the combination of germination and ensiling resulted in changes in the chemical composition and improved the digestibility of sorghum grains. The grinding of grain before reconstitution and ensiling is an alternative to increase the sorghum grain digestibility and nutritive value.