Acta Vet. Brno 2007, 76: 39-44
Adsorption of Zinc Contained in the Poultry Feedstuff onto Clinoptilolite
The aim of this work was to find whether an adsorbent used as an additive in the feed mixtures could influence the concentration of free available zinc. The feed supplement ZeoFeed, which often constitutes a part of animal feed mixtures, mainly for poultry, was used as adsorbent in the amount of 10 g kg-1 of the feed mixture. A substantial part of ZeoFeed is clinoptilolite, a natural form of zeolite. Two sample preparation methods were used for the determination of zinc. The microwave-assisted wet digestion method was used to achieve a complete decomposition of the feed mixture in order to determine the total zinc concentration. The extraction method represented a simplified model of the processes in the digestive fluid tract. The extraction was done under laboratory temperature for 30, 60 and 120 min. Concentrations of zinc both in digests and extracts were determined by the method of the differential pulse anodic stripping voltammetry. The total zinc concentration (mean ± 95% confidence interval) in the feed mixture without addition of clinoptilolite was found to be 145 ± 32.0 mg kg-1 and in the feed mixture with added clinoptilolite 146 ± 11.5 mg kg-1. The concentrations of free available zinc were approximately ten times lesser than the total amount. The analysis of extracts showed that no statistically significant differences between concentrations of zinc in extracts without clinoptilolite and with clinoptilolite addition have been found. The extraction time did not affect the extracted amount of zinc significantly. In addition to zinc, also other three trace elements, namely the essential trace element copper and the toxic trace elements cadmium and lead, were measured. However, these data have only preliminary value and need further verification.
