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Zinc has many biological functions, such as anti-inflammation, anti-diarrhea and maintaining epithelial barrier integrity. In particular, zinc oxide (ZnO) appears to have a strong protective effect in resisting intestinal diseases. Feeding pharmacological level of Zn (2000–4000 mg/kg of Zn as ZnO) to weaned pigs is widely used in the pig industry worldwide due to its proven effects on alleviating post-weaning diarrhea and improving performance. However, the strategy is criticized because high levels of zinc are excreted into the environment and posed an environmental problem. It has been hypothesized that zeolite may have controlled-release characteristic for ZnO, and Z-ZnO may be a potential substitute for pharmacological addition of ZnO in alleviating postweaning diarrhea of piglets. Therefore, the objective of the present experiment was to determine whether feeding lower concentrations of Zn from Z-ZnO to weaned pigs would alleviate postweaning diarrhea and improve intestinal barrier function comparable to feeding pharmacological levels of Zn. In this study, the effects of Z-ZnO on growth performance, intestinal microflora and permeability and cytokines expression of weaned pigs were investigated. A total of 210 piglets, with BW of 6.12 ± 0.22 kg weaned at 21 ±1 d age, were randomly allotted to five groups for two weeks. The five treatments were the control (basal diet), and the basal diet supplemented with 300, 600 or 900 mg Zn/kg from Z-ZnO or 2250 mg Zn/kg from ZnO.
The results showed that incremental levels of Z-ZnO increased average daily gain (linear P=0.001; quadratic P=0.004), daily feed intake (linear P=0.006; quadratic P=0.019) and jejunal transepithelial electrical resistance (linear P=0.007; quadratic P=0.021), and decreased the postweaning scour scores (linear P<0.001; quadratic P<0.001), the viable counts of Clostridium and Escherichia coli in small intestinal contents (linear P<0.001; quadratic P<0.001). At 7 days after weaning, on d 7 postweaning, as Z-ZnO inclusion increased, the mRNA levels of TNF-α and IFN-γ in jejunal mucosa were linearly decreased (P<0.001 and P=0.001) and quadratically (P<0.001 and P=0.001), and those of TGF-_1 and IL-10 were linearly increased (P=0.002 and P=0.010) and quadratically (P=0.009 and P=0.028).
The results indicated that supplementation with 600 or 900 mg Zn/kg from Z-ZnO has the same efficacy than 2250 mg Zn/kg from ZnO in enhancing growth performance, alleviating postweaning diarrhea, improving intestinal microflora and barrier function of weaned pigs.
C.H. Hu, K. Xiao, J. Song, Z.S. Luan (2013). Effects of zinc oxide supported on zeolite on growth performance, intestinal microflora and permeability, and cytokines expression of weaned pigs. Animal Feed Science and Technology 181; 65– 71. http://dx.doi.org/10.1016/j.anifeedsci.2013.02.003