Determination of metals in fresh cow's milk under different feeding regime in Wolaita zone, southern Ethiopia

Abstract

Milk is an important food in the human diet, both in its original form and in various dairy products. Feed is one of the sources of accumulation of heavy metals in milk and determining these elements in milk under different feed types is vital. Thus, this study was conducted to determine some selected metals in the fresh milk of two cow groups: grass-eaters; and "frushka" (wheat bran) and grass-eaters in Wolaita Sodo Zuriya woreda, southern Ethiopia. Eighteen milk samples were collected from both cow groups in three representative kebeles. Before the sample analysis, the working procedure was optimized, and the determination of metals was made by flame atomic absorption spectrometry. The percentage recoveries of the metals were in the range of 83.3% to 118%. The ranges of the concentrations (in mg/l) of the metals on a dry weight basis are magnesium (Mg) (130.72 – 164.26), calcium (Ca) (627.95 – 847.70), iron (Fe) (1.43 – 2.40) and Zinc (Zn) (2.85 – 5.53). Lead (Pb) and cadmium (Cd) were below the detection limit. There is a significant difference in the mean concentrations of the detected metals between the milk samples from three kebeles and under two feeding regimes. According to the findings, fresh milk is rich in calcium and magnesium and has better zinc and iron content. In most cases, the metal concentration in milk obtained from "frushka" and grass-eating cows is greater than that of grassonly eaters.