Effect of tannic acid on rumen degradation and intestinal digestion of treated soya bean meals in sheep

The current experiment was conducted to study the effect of different doses of tannic acid, a hydrolysable tannin, on ruminal degradation and post-rum inal digestion of treated soya bean meals (SBM) in sheep. Samples of SBM we re prepared by spraying 100 g SBM with 100 mi distilled water containing 0, 1, 5, 10, 15 or 25 g of commercial tannic acid (S-0, S-TA1, S-TA2, S-TA3, S-TA4 and S-TA5, respectively). Three ruminally cannulated awes, that had n ever consumed tannic acid previously, were used to determine in situ degrad ability of tannic acid-treated SBM. Intestinal digestibility of protein rem aining after 16 h rumen incubation was estimated in vitro. Extent of rumen degradation of SBMs was significantly (P < 0.05) affected by the tannic aci d treatment. All doses of tannic acid used in this experiment, even the low est one (S-TA1), significantly decreased the extent of N degradation but on ly doses higher than that used to treat S-TA3 reduced the extent of DM degr adation. This reduction in the extent of DM and N degradation was mainly du e to a marked decrease in the immediately degradable fraction (a), which wa s observed in all treated SBM, and to a lower rate of degradation (c), obse rved in meals S-TA3, S-TA4 and S-TA5. Intestinal digestion of the non-degra ded protein was decreased (P < 0.05) by treatment with the two highest dose s of tannic acid (those used to treat meals S-TA4 and S-TA5). It was theref ore concluded that tannic acid can exert a negative effect both on rumen de gradation and on intestinal digestion of SBM, this effect being clearly dep endent on the dose used to treat the SBM.