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.
Keywords: antioxidant capacity; diarrhea rate; ileum; microbiota; piglets.