Changes during lactation in the mineral element content of mare milk produced in semi-extensive rural farms

Abstract

This study characterizes, for the first time, the content of individual mineral elements in mare milk from Basque Mountain Horse breed, as well as changes that occur during lactation and among semi-extensive rural farms. Individual milk samples from eighteen mares belonging to three commercial farms were collected along six months of lactation, and the contents of eleven mineral elements in milk were determined using a triple quadrupole inductively coupled plasma mass spectrometer (ICP-MS). Basque Mountain Horse milk contained calcium (Ca; 958 ± 248 μg/g milk), potassium (K; 581 ± 117 μg/g milk), phosphorus (P; 454 ± 160 μg/g milk), sodium (Na; 141 ± 38 μg/g milk), magnesium (Mg; 64.1 ± 15.7 μg/g milk), zinc (Zn; 2.50 ± 0.88 μg/g milk) and copper (Cu; 0.343 ± 0.179 μg/g milk) amounts similar to those reported in other horse breeds. Conversely, low sulphur (S; 156 ± 42 μg/g milk) and chlorine (Cl; 49.3 ± 33.4 μg/g milk), and high iron (Fe; 2.43 ± 2.44 μg/g milk) contents were found. Mn was only quantifiable in 12% of the samples. The content of all macrominerals, except Na and Cl, decreased at the end of lactation, while that of trace elements (Zn, Cu and Fe) either increased or fluctuated. In addition, the content of Ca, P, S and Na differed significantly among semi-extensive rural farms, probably due to differences in feeding management. From a multivariate perspective, the mineral element composition of the milk made it possible to differentiate samples from early, mid and late lactation stage.