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The presence of microystins (MCs) in water has the potential to harm people's health. In the MCs various isomers, MC-LR has the strongest toxicity and is the most harmful one. At present, several kinds of pre-oxidants, which are commonly used in water treatment process, are effective to remove MC-LR. However, it is still not clear about their degeneration mechanisms. Chlorine and potassium permanganate were selected in the present work since they are used worldwide for preoxidation treatment. Using the testing method of HPLC-MS, studies on the degeneration of MC-LR were conducted. The results indicate that HPLC-MS is creditable and sensitive. It was also found that linear relationship between concentration of MC-LR and peak area holds in the range of 5-500 microg.L(-1) on the calibration curves, the correlation coefficient (R2) is 0.9993. Under the general condition of oxidant dose and reaction time, MC-LR was degraded rapidly. With active chlorine and potassium permanganate the degradation reaction followed the mode of first-order kinetics. The molecular weight of the degradation product was determined through analyzing the full-scan mass spectrum of MC-LR. And the oxidative degradation mechanism of MC-LR was discussed as well.

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The effects of dietary hydrolyzed Chinese gallnut tannic acid(GCT) as a replacement for ZnO were investigated on weaned piglets. A total of 72 weaned piglets at 31 ± 1 day (six replicate pens per treatment with six piglets per pen) were selected and divided randomly into two groups: a control group, with a basal diet of + 1600 mg/kg ZnO; and a treated group, with a basal diet of + 1899.5 mg/kg GCT. Data analysis showed that the significance of average daily gain and average daily feed intake between the two groups was p = 0.731 and p = 0.799, respectively. Compared with the control group, the diarrhea rate of piglets in the treated group underwent no noticeable change on days 0–7 (p = 0.383) and 7–14 (p = 0.263), but decreased significantly on days 14–21 (p < 0.05). Additionally, we found GCT can reduce the crypt depth of the ileum and improve its antioxidant capacity (p < 0.05). High throughput sequencing showed that GCT increased the richness of the bacteria Lachnospiraceae (p = 0.005), Prevotella_2 (p = 0.046) and Lactobacillus amylovorus (p = 0.081), which are associated with the degradation of cellulose and hemicellulose. The study indicated that 1899.5 mg/kg GCT could be an alternative for 1600 mg/kg ZnO in the diet of piglets.

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