Abstract

To evaluate behavior of E. coli in feces of dairy cows added with hydrolysable tannins, an experiment was conducted, in which aliquots of 100 g were randomly assigned to two hydrolysable tannins levels (0 or 10%), three values of pH 5.2, 6.5 and 8.3, and cultured at 0, 2, 6, 9, 15, 22, and 30 days after tannins addition. Feces added with HT 10% shown the highest E. coli growth (P < 0.01) compared to those that did not received HT (Log10 5.071 vs. Log10 4.401). Feces with 6.5-pH value had lower values (P < 0.01) of E. coli (Log10 4.525) vs. pH 5.2 (Log10 4.866), and pH 8.3 (Log10 4.816). In all cases the E. coli growth diminished (P < 0.01) as increased days number (Log10 = 5.51 day 0; Log10 = 3.36 at day 30). The results suggest that HT did not inhibit E. coligrowth in feces of cows; however, at pH values close to neutrality the E. coli growth decreases. Key words: Escherichia coli, hydrolysable tannins, cows, pH.

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