Macro- and microminerals in the whole raw milk of dairy cows from conventional and organic farms: A meta-analytical study
The objective of this meta-analytical study was to investigate selected macrominerals (calcium (Ca), magnesium (Mg), phosphorous (P), potassium (K), and sodium (Na) and microminerals (copper (Cu), iodine (I), iron (Fe), manganese (Mn), selenium (Se), and zinc (Zn) in the bovine whole raw milk samples from two different management systems and 19 countries. An analytical dataset was constructed from 44 different studies and 19 countries with two types of production systems: conventional and organic. No differences in concentrations of Ca, Mg, and Na in the raw milk were observed when production systems were compared, whereas, concentrations of P and K were greater in the conventional production system (P<0.05). The average concentrations of Cu, I, Fe, Mn, Se, and Zn in organic whole raw milk samples were 1.12, 1.77, 8.25, 0.47, 0.30, and 42.20 μmol/L respectively; and were lower (P<0.05) compared with conventional milk (2.09, 2.37, 13.62, 1.97, 0.76, and 60.95 μmol/L respectively). The lowest concentrations of Cu (0.03 μmol/L), Se (0.17 μmol/L), and Zn (31.76 μmol/L) were reported in bovine raw milk samples from Italy, whereas Germany (Cu, 12.89 μmol/L) and Turkey (Se and zinc, 194.31, and 125.40 μmol/L respectively) had greater concentrations of those elements (P<0.05). Raw milk samples from Polish and Czech dairy farms had greater concentrations of I (2.76 and 3.31 μmol/L respectively) compared to samples collected in Niger (0.17 μmol/L) and Germany (0.88 μmol/L). Iron levels varied from 3.47 μmol/L (USA) to 89.53 μmol/L (Pakistan) (P<0.05). The lowest concentrations of Mn were observed in the milk samples from USA and Poland (0.38, and 0.48 μmol/L respectively), whereas the highest concentrations were reported in milk samples from China (5.89 μmol/L) and Republic of South Africa (3.62 μmol/L). In conclusion, data from this study indicate that concentrations of microelements in the samples of whole raw milk were lower in organic farms compared with the conventional production system. Moreover, milk samples originating from developed countries were characterized by normal concentrations of these minerals compared with other countries.
Keywords: whole raw milk, macro- and micro-minerals, production system