Effects of montmorillonite–zinc oxide hybrid on performance, diarrhea, intestinal permeability and morphology of weanling pigs

Effects of montmorillonite–zinc oxide hybrid (MMT–ZnO) on performance, diarrhea, intestinal permeability and morphology were investigated. A total of 180 piglets (Duroc × Landrace × Yorkshire, average initial weight of 7.2 ± 0.3 kg weaned at 27 ± 1 d age) were randomly allotted to five groups for two weeks, each of which has six pens with six pigs per pen. The dietary treatments were: (1) basal control diet, 100 mg/kg of supplemental Zn as ZnSO4; (2) basal diet + 2.0 g/kg montmorillonite (MMT), equivalent to the MMT in the MMT–ZnO treatment; (3) basal diet + 500 mg/kg of Zn as ZnO; (4) basal diet + 500 mg/kg of Zn as MMT–ZnO; (5) basal diet + 2000 mg/kg of Zn as ZnO. The results showed that supplemental 500 mg/kg of Zn from MMT–ZnO or 2000 mg/kg of Zn from ZnO improved (P<0.05) average daily gain and daily feed intake, decreased (P<0.05) fecal scores at 7 and 14 d postweaning, reduced (P<0.05) plasma d-lactate and diamine oxidase activity, improved (P<0.05) villus height and the villus height:crypt depth ratio at the jejunal mucosa as compared with the control, MMT or 500 mg/kg of Zn from ZnO. Pigs fed with 500 mg/kg of Zn as MMT–ZnO had lower (P<0.05) plasma levels of d-lactate than those fed with 2000 mg/kg of Zn as ZnO. Pigs fed with 500 mg/kg of Zn as MMT–ZnO had lower (P<0.05) number of intestinal Clostridium and Escherichia coli than those fed with the control, MMT or 500 mg/kg of Zn as ZnO. Supplementation with 2000 mg/kg of Zn as ZnO reduced (P<0.05) the number of Clostridium in proximal colon as compared with the control while had no (P>0.05) influence on intestinal E. coli. Supplemental MMT or 500 mg/kg of Zn from ZnO had no (P>0.05) effect on growth performance, intestinal microflora, permeability and morphology as compared to the control group. The results indicated that dietary addition of 500 mg/kg of Zn from MMT–ZnO was comparable to 2000 mg/kg of Zn from ZnO while more effective than MMT or 500 mg/kg of Zn from ZnO for enhancing growth performance, alleviating diarrhea, as well as improving intestinal microflora, mucosal barrier integrity and morphology of weaned pigs.