Cadmium levels in feed components and kidneys of growing/finishing pigs

Cadmium (Cd) concentrations in pig feeds (one control feed and one feed with reduced nitrogen content), straw, water, and pig kidney cortex were determined in 2 breeds of growing/finishing pigs (n = 96). The total Cd intake from feed was calculated. Feed mixtures and components, straw and kidney cortex samples, and certified reference samples were microwave-digested and analyzed by atomic absorption spectrometry with graphite furnace technique. Total Cd concentration in the control feed was 37.1 micrograms/kg wet weight (w.wt). The highest Cd levels were found in nonlocally produced feed components: vitamin-mineral mixture, lime, dicalcium phosphate, soybean meal, and rapeseed meal. These components contributed 70% of the Cd content in the feed. The main component, barley, which was locally produced, contributed 30% of the total Cd content in feed. The feed with reduced nitrogen content contained less soybean and rapeseed meal and a lower Cd level than the control feed. The Cd levels in kidney cortex varied from 38.0 to 105 micrograms/kg w.wt, with a mean level of 70.9 micrograms/kg. The levels differed between breeds and feeds, but not between gender. There was a significant correlation between Cd level in kidney cortex and age at slaughter, with an increase of 2.8 micrograms/kg w.wt in the kidney for each additional week of survival. The contribution of Cd from nonlocally produced feed components could have environmental effects through application of farmyard manure to local soils.