Effects of zinc-exchanged montmorillonite with different zinc loading capacities on growth performance, intestinal microbiota, morphology and permeability in weaned piglets

• Providing 150 mg Zn/kg, the in vivo efficacy of three Zn-Mts is different.
• Zn-Mt2 and Zn-Mt3 increased average daily gain of weaned pigs.
• Zn-Mt2 and Zn-Mt3 decreased intestinal E. coli and Streptococcus suis of weaned pigs.
• Zn-Mt2 and Zn-Mt3 improved intestinal morphology and barrier function of weaned pigs.

Three zinc-exchanged montmorillonites (Zn-Mt1, Zn-Mt2, and Zn-Mt3, the amount of Zn adsorbed on Mt was 6.3 × 104, 5.1 × 104 and 4.2 × 104 mg/kg, respectively) were used to study the effects on growth performance, diarrhea, intestinal microbiota and barrier function in weaned piglets. A total of 144 piglets (Duroc × Landrace × Yorkshire), weaned at 21 ± 1 d with average initial body weight of 6.5 kg were allotted to four treatments groups for two weeks. Four treatments were: (1) control: basal diet; (2) ZM1: basal diet + 150 mg/kg Zn as Zn-Mt1; (3) ZM2: basal diet + 150 mg/kg Zn as Zn-Mt2; and (4) ZM3: basal diet + 150 mg/kg Zn as Zn-Mt3. Results showed that, compared with the control, supplementation of Zn-Mt2 or Zn-Mt3 improved (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI), and lowered (P < 0.05) fecal scores. Supplemental Zn-Mt2 or Zn-Mt3 increased (P < 0.05) villus height and the ratio of villus height and crypt depth at the jejunal mucosa. Supplementation of Zn-Mt2 or Zn-Mt3 decreased (P < 0.05) the number of Escherichia coli and Streptococcus suis, the paracellular permeability of fluorescein isothiocyanate dextran 4 kDa (FD4), but increased transepithelial electrical resistance (TER) in jejunum and colon of weaned piglets. No difference was observed between the Zn-Mt1 group and the control group. The results indicated that the in vivo efficacy of three Zn-Mts was different. Supplementation of Zn-Mt2 was as effective as Zn-Mt3 in enhancing growth performance, alleviating diarrhea, as well as improving intestinal microbiota, barrier function of weaned pigs under our trial conditions.