A study on the effect of levels of tannins on in vitro digestibility of different Sudanese varieties of sorghum grains

This work was conducted to evaluate the tannin content and its effect on ruminant's digestibility in 26 Sudanese sorghum varieties. Samples were brought from Agricultural Research Corporation, Wad Medani (ARC), hand cleaned and preserved in dark in plastic containers. Tannins content was measured by using vanillin-HCl method (Price et al, 1979) and in vitro digestibility was conducted to evaluate the dry meter digestibility and organic matter digestibility according to (Tilley and Terry, 1963). Results have shown that condensed tannins (vanillin-HCl) ranged between 0.39 g/kg and 23.08 g/kg, Tabat recorded the lowest value when Wad akar red recorded the highest value. An in vitro dry matter digestibility (INVDMD) and organic matter digestibility (OMD) trial were performed. There was a negative correlation (P<0.05) between organic matter and condensed tannins especially those contained high level of condensed tannins. The organic matter digestibility ranged between 680.11 g/kg in arfa gadamak commercial to 828.85 g/kg in dar baladi. The results have shown that the addition of polyethylene glycol (PEG) to in vitro incubated samples increased the gas produced in wad akar red in 24 hours by 29% compared to the control sample without (PEG). Higher significant correlation (P<0.001) between the clorox bleaching test and condensed tannins (vanillin-HCl) in samples was found. It is concluded that condensed tannins in sorghum are beneficial to ruminant when they are introduced in complete diets to avoid the inhibitory effects of condensed tannins in sorghum. Adding (PEG) to the ruminant diets which contain high levels of condensed tannins improved digestibility subsequently animal performance.(Author)