Effect of microbial phytase on cadmium accumulation in pigs.

Abstract

2 x 6 pigs continuously housed in metabolic cages from 25-100 kg weight were fed N-reduced diets based on barley, maize and soybean meal. Diet I (control) contained in FM (fresh matter) 0.56%, 0.48% and 0.46% P (feeding phases A: 25-50 kg, B: 50-75 kg, C: 75-100 kg weight) and 0.76%, 0.71% and 0.68% Ca. Diet II was low in P (0.46%, 0.40%, 0.32%) and Ca (0.69%, 0.62%, 0.52%) and 800 U Aspergillus-phytase per kg were added. Analyzed cadmium concentrations in diet I were 23.4, 19.9 and 13.7 micrograms/kg FM and 20.6, 14.9 and 12.7 micrograms/kg FM in diet II respectively. At 100 kg weight in both treatment groups low cadmium concentrations in liver (11.8 vs. 17.3 micrograms Cd/kg FM) and kidneys (59.6 vs. 102 micrograms Cd/kg FM) were found. Contrary to findings for rats fed semisynthetic diets enriched with high CdCl2 levels, phytase supplementation to the P- and Ca-reduced pig diet with a low Cd concentration significantly enhanced liver and kidney cadmium accumulation. Differences in dietary Cd levels, the binding form of Cd in the diets and the duration of the experimental trials may partially explain the differences found between rats and pigs. Complex interactions between cadmium and various elements, especially calcium, might also have additionally influenced the carry over of cadmium in the present study. Irrespective of the dietary treatment, liver and kidney cadmium concentrations in both groups were considerably lower than maximal permitted values.