Assessment of heavy metals in chicken feeds available in Sokoto, Nigeria

In the present work six metals (Cu, Pb, Zn, Cd, Mn and Ni) were analyzed for, using atomic absorption spectrophotometry in three main feed brands commonly used in Sokoto (2 commercial feed and 1 locally compounded chicken feed). Initially, the samples were digested with concentrated nitric acid and perchloric acid at about 370℃ to 450℃ heat in a digestion block. The concentration in μg/ml of the six metals analyzed for in the feed samples ranged between 0.04 and 1.21 for Cu, 0.01 and 0.55 for Pb, 1.43 and 11.65 for Zn, 0.10 and 0.12 Cd, 0.94 and 3.12 for Mn and 0.004 and 0.25 for Ni. In most of the analyzed samples, the concentration of Cu, Zn, Mn and Ni was found to be lower than the nutritional requirement of broiler chicken at a level which could be harmful for the poultry. Also the study showed the presence of heavy metals (Pb and Cd) in all the feed samples analyzed, but none exceeded permissible levels as set by European Union and National Research Council.