Nickel content in raw cow's, ewe's and goat's milk

Abstract

Changes in concentrations of nickel present in cow's, ewe's and goat's milk were studied monthly (n = 360 samples) by using graphite furnace atomic absorption spectrometry. The mean concentrations of nickel are 15.0 ± 3.81, 18.6± 2.50 and 13.6 ± 2.46 μg·kg-1 of fresh weight for cow's, ewe's and goat's milk respectively. Two-factor (species and time period) variance analyses were made on the three types of milk investigated and Tuckey's mean homogeneity test (P < 0.05) was also carried out for the formation of homogeneous groups per species for nickel content. Significant changes (P < 0.001) were determined overtime in the nickel content of the three species studied and two homogeneous groups were formed, one for cow's and goat's milk and an other for ewe's milk with the higher nickel content. For the three species, the monthly changes of the nickel content correspond to a mathematical model of 3rd grade and these models cannot be utilised to make predictions over time. © Inra/Elsevier. Paris.