Research: Clays and zinc in weanling pigs

Montmorillonite is an organic clay and incorporate with zinc oxide a montmorillonite – zinc oxide hybrid (MMT-ZnO) is formed.

For the trial 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.

Results
The results showed that supplemental 500 mg/kg of Zn from MMT-ZnO or 2000 mg/kg of Zn from ZnO

• improved average daily gain and daily feed intake,
• decreased faecal scores at 7 and 14 d postweaning,
• reduced plasma d-lactate and diamine oxidase activity,
• improved 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 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 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 the number of Clostridium in proximal colon as compared with the control while had no influence on intestinal E. coli.

Supplemental MMT or 500 mg/kg of Zn from ZnO had no effect on growth performance, intestinal microflora, permeability and morphology as compared to the control group.

Conclusion
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 diarrhoea, as well as improving intestinal microflora, mucosal barrier integrity and morphology of weaned pigs.