Content of Selected Macroelements and Zinc in Relation to Stage of Lactation of Montbéliarde and Polish Holstein-Friesian Cows

The aim of this study was to determine the effect of a cow’s breed on the content of minerals in milk depending on the stage of lactation. The study material was the milk of cows of two breeds, Montbéliarde (mb; n = 15) and black-and-white Polish Holstein-Friesian (phf; n = 15), kept at the same farm. The phf cows were matched with the mb cows by analogs considering the stage and number of successive lactations. Milk for analysis was collected six times during lactation when the official test milking was performed, and a total of 180 milk samples were collected. The fresh milk was analyzed for its proximate chemical composition and mineral content (Ca, Mg, K, Na and Zn), which were identified in the mineralization by flame atomic absorption spectrophotometry. Milk of the Montbéliarde cows contained significantly more sodium, calcium, magnesium and zinc compared to milk of the Polish Holstein-Friesian cows. This enables the conclusion that the contents of these elements are determined by breed. This study demonstrates the variability of the contents of the analyzed minerals with time after calving. During lactation, the contents of potassium, calcium, magnesium and sodium were the highest at the late stage of lactation, especially in the tenth month of lactation.