2. Materials andmethods
2.1. Animals and palygorskite
The palygorskite used in this study was of 94% purity and provided by
our laboratory. The physico-chemical properties and heavymetal content
of the palygorskite used are shown in Table 1. Determination of mineral
composition was carried out by X-ray diffraction, using a Dmax 12 kw
powder diffractometer. The measurement of cation exchange capacity
and ethylene blue absorption was performed according to the method
described by Yongduo and Gaoxiang (2004). The contents of Pb and Cd
were determined by the flame atomic absorption spectrometry method,
Hg by the atomic absorption spectrometrymethod, Cr by the colorimetric
method. All themeasurements for heavymetals were under the limits of
General Rules of Natural Mineral Feed (GB/T 22144—2008) in China for
animal feed. Twenty-seven castrated male weaned piglets (Large
White×Great Yorkshire) with a weaning age of 24 days and an average
initial weight of 7.32 kg±0.12 kg were housed in metabolism cages.