Concentration of trace elements in raw milk depending on the lactation period and age of cows
2011
Gorska, A.,University of Natural Sciences and Humanities, Siedlce (Poland). Chair of Cattle Breeding and Milk Evaluation | Oprzadek, K.,University of Natural Sciences and Humanities, Siedlce (Poland). Inst. of Chemistry
Concentrations of iron, zinc, manganese and copper in milk from cows of Polish Holstein - Friesian Black-White breed kept on five farms located in the southern Podlasie region in Poland were determined and analysed depending on the lactation period and age of cows. Milk samples were taken separately from each cow, 18 samples from one farm. A total of 90 milk samples were taken. Cows were in three age classes (lactation number): 1, 2-3 and more than 3, and four lactation periods (duration): less or equal to 100, 101-200, 201-305 and more than 305 days. The concentration of trace elements in milk was determined using atomic absorption spectrometry. Average concentrations of the elements in 1 kg of fresh milk were as follows: Fe 173+/-84 microg, Zn 3.6+/-0.9 mg, Mn 27+/-17 microg and Cu 40+/-23 microg. A relation between the age of cows and Fe concentration was observed. The lowest Fe levels (145+/-72 microg/kg) were observed in the milk from the youngest cows in their first lactation, whereas the highest contents (217+/-70 microg/kg) were observed in the milk from the oldest cows above the third lactation. No relation between the age of cows and the concentrations of Zn, Mn and Cu in milk was observed. Similarly, no significant differences between the levels of these elements in different lactation periods were observed.
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