Assessing the Level of Some Essential and Non-Essential Metals in Milk of Local, Holstein-Friesian and Cross Breed Cows in Dembecha Town, West Gojjam, Amhara Regional State, Ethiopia

Abstract

The analysis of the level of essential and non-essential metals in milk sample was very important for understanding the nutritional quality of milk for use. This research is aimed to determine the concentration of some selected essential and non-essential metals in the three breeds (Holstein Friesian, Cross breed and local cow's) of cow milk in Dembecha Town, Amhara regional state,Ethiopia using flame atomic absorption spectroscopy. The mineralization of milk sample was done by wet digestion using a mixture of 10.5 mL of HNO3 (69-72%) and 4.5 mL HClO4 (70%) in triplicate for 30 minutes at a temperature of 60 oC on Hot plate digestion block. The mean levels of metals determined in mg/L of the three breeds of cow's milk were Ca(485±7.58), Mg(217.6±2.30), Fe(27.9±0.36), Zn(9.56±0.21), Mn(0.72±0.01), Cu(1.69±0.04), for Holstein Friesian cow's milk; Ca(289±1), Mg(91.66±2.06), Fe(19.46±0.58), Zn(5.86±0.04), Mn(0.25±0.01), Cu(0.76±0.02), Ni(0.45±0.02),for Local cow's milk; and Ca(450±17.60), Mg(170.44±2.13), Fe(20.7±0.26), Zn(7.8±0.26), Mn(0.45±0.02), Cu(1.32±0.04), Ni(0.16±0.00), for Cross breed cow's milk. Ni metal in Holstein-Friesian cow's milk and Pb and Cd in all the three milk samples were not detected in this study. The highest mean concentration of Ca in all samples was within the range of (289-485) mg/L. The accuracy of the procedure was validated by spiking experiment and % recoveries of all the metals were in the range of 85.2 to 104 which is within the accepted range. The precision of the triplicate analysis were evaluated using %RSD and all metals have less than 10% in the three breeds of cow milk samples. The heavy metal concentration results of the present study is comparable to those values reported by different authors and were below the maximum permissible level set by international dairing federation (IDF) in milk samples.