The content of minerals in milk of small ruminants
¹Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Department of Chemistry, Kamýcká 129, CZ 165 21 Prague, Czech Republic
²Dairy Research Institute Ltd, Ke dvoru 791/12A, CZ 160 00 Prague, Czech Republic
The aim of this study was to determine and compare the content of sodium, potassium, calcium, magnesium, zinc, copper, lead, and cadmium in sheep and goat milk of different breeds from 9 farms in the Czech Republic (herds of 18–330 goat´s heads and 30–380 sheep heads). Pool samples of milk were collected once a month (April – September) during lactation in the years 2011–2013. The content of minerals was determined using atomic absorption spectroscopy. Most of the analyses of the contents of Cd and Pb were below the limit of detection. Other determined values of these two contaminants were lower than maximal tolerable amount according to previously valid regulation No. 298/1997 Sb of the Ministry of Health of the Czech Republic given for cow's milk. The contents of each element in the whole of the reference period were in a relatively wide range. Determined levels of Ca, Mg, K, Na, Zn and Cu in goat milk related to the weight of lyophilized milk powder varied from 1.40–8.08 g kg-1, 0.16–1.42 g kg-1, 8.16–31.10 g kg-1, 0.72–5.43 g kg-1, 7.59–44.10 mg kg-1, and 0.21–1.46 mg kg-1 respectively. Determined levels of Ca, Mg, K, Na, Zn and Cu in sheep milk varied from 1.69–9.13 g kg-1, 0.21–1.36 g kg-1, 3.53–11.90 g kg-1, 0.65–5.05 g kg-1, 13.70–34.30 mg kg-1, and 0.15–2.10 mg kg-1 respectively. Statistically higher (P < 0.05) content of potassium was determined in goat milk in comparison with sheep milk. The contents of all followed minerals in milk samples from each farm collected during the lactation period were very variable, but it is not possible to find any direct relationship between the content of studied elements and the date of sampling. It was found that the year has statistically significant influence especially on the content of Ca and Mg in milk of small ruminants.