Use of nuclear and related techniques to develop simple tannin assays for predicting and improving the safety and efficiency of feeding ruminants on tanniniferous tree foliage: Achievements, result implications, and future research

The microbial attachment to and gas production from α-cellulose (Sigma; C-8002) without and with mimosa tannin (MT), pectin (P), polyethylene glycol (PEG), MT + P or MT + PEG, were investigated using the in vitro gas production system. Microbial attachment based on 15N-labelled rumen microorganisms in the residual pellet after 24 h incubation was estimated, which varied from 113.7 to 161.3 μg 15N per g residual pellet. C + MT had the lowest microbial attachment (P < 0.05) of all treatments and C + P the highest (P < 0.05). Both pectin and PEG improved microbial attachment when added to C + MT (P < 0.001). oduction was measured at 2, 4, 6, and 24 h. Mimosa tannin drastically reduced gas production only at 24 h (P < 0.001). Pectin increased gas production throughout the incubation period (P < 0.001). Both pectin and PEG increased gas production at 24 h, when added to C + MT (P < 0.05), however, for C + MT + P, the gas production was only half (P < 0.05) of the gas produced in the control (when only C incubated). A rapid degradation of pectin early in the incubation could have reduced the interaction of pectin with the MT. ial attachment agreed well with gas production at 24 h (R2 = 0.84, P < 0.001). However, the inclusion of MT and pectin may have resulted in differences in microbial profiles, thereby altering the capability of the adhered microbes to degrade cellulose. This assertion is supported by the lower gas production (ml per μg of 15N) in the residual pellet measured for C + MT (0.054) and C + MT + P (0.159), compared with the other treatments (0.32 for C; 0.34 for C + P; 0.33 for C + PEG; and 0.33 for C + MT + PEG). oncentration of 194 g/kg diet reduced microbial attachment and activity of rumen microorganisms in vitro. Polyethylene glycol counteracted the effect of MT on microbial attachment and activity. Pectin exerted a beneficial effect on attachment and fermentation in the initial hours of incubation. A ratio of pectin to MT of 1:1 improved microbial activity of C + MT but inhibition of microbial activity by MT remained at 24 h as indicated by the lower gas production of C + MT + P compared with the control. sults support the hypothesis that there is considerable interaction between tannins, microbes and non-starch-polysaccharides (NSP) in animal feeds and that these interactions may influence the functional ability of microbes in the gastrointestinal tract of animals.