Milk quality determined using chemical analysis and microwave plasma atomic emission spectrometry as a function of seasonality in two conventional Italian dairy farms

Milk contains macrominerals and trace elements which are essential for animal and human nutrition, but it also contains elements whose biological role is not well known and which could even potentially be toxic. The investigation reported in this research paper aimed to evaluate the mineral content of milk from two different seasons (summer and winter) on two different conventional Italian farms within the Lombardy region (Italy). The mineral composition (macrominerals: calcium, potassium, magnesium; microelements: iron, copper, zinc, selenium, manganese; heavy metals: cadmium, chromium, barium) and proximate composition were analyzed on bulk tank milk collected weekly. The results of the proximate composition showed values comparable to other studies and the bovine milk market; however, the season influenced the protein content, which was higher (p < 0.05) in winter than summer. The mineral content of the analyzed milk varied between the seasons (p < 0.005) in all minerals, except for iron, chromium and zinc. No effects were found from the farm, except for in Fe and Mn. Cd was only detected on one farm as a trace element. The current study shows that milk composition and mineral concentration vary little between dairies, confirming the typical composition of Holstein Friesian milk cows.