Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

Forty randomly selected chickens were allocated into four groups: K, HA, Cd and Cd + HA. After a 5-day adaptation period, the experiment was initiated. Group K was fed a diet without supplements. Group HA was fed the same diet with a 0.5 g supplement of humic acid per chicken/day. Group Cd was treated with 0.147 mg Cd per chicken/day (0.3 mg of CdCl2·2.5H2O), and Group Cd + HA was given the same treatment as the latter group, with an additional 0.5 g humic acid per chicken/day. The chickens were given the above mentioned treatment daily, for 10 days. Subsequently, they were slaughtered and samples from livers, kidneys and leg muscle (m. flexor perforans et perforatus) were collected and Cd levels determined. The Cd levels detected in Group K are commonly found in market chickens and were assumed to be base background value; these represent 32%, 5.2% and 20% of allowed maximum residual limit (MRL) in kidney, liver and muscle, respectively. The limits are 1.0; 0.5 and 0.05 mg/kg for kidney, liver and muscle, respectively. The ten-day treatment with 0.147 mg Cd/day, i.e. 1.47 mg Cd per 10 days, significantly increased Cd levels in all investigated tissues. Average levels in kidneys, livers and leg muscle were 4.99 ± 1.57, 0.558 ± 0.630 and 0.052 ± 0.008 mg Cd/kg, respectively. When cadmium chloride was given together with humic acids, (group Cd + HA), Cd levels decreased in all investigated tissues by 39.6%, 34.2% and 80.8% in kidney, liver and muscle, respectively. The average levels were 3.012 ± 1.33, 0.361 ± 0.367 and < 0.01 mg/kg in kidneys, livers and leg muscle, respectively.