Influence of feeding systems and seasons on the basic composition and content of fat-soluble antioxidants and on the antioxidant activity of cow's milk

Abstract. The aim of this study was to assess the quality of raw milk, with a special focus on the content of fat-soluble antioxidants and antioxidant activity, depending on the production system (intensive, traditional), production season (spring/summer, autumn/winter), and breed of cow (Polish Holstein–Friesian, Simmental). The basic chemical composition of milk, i.e., fat content, lactose, protein (including casein), and dry matter, as well as the somatic cell count (SCC), concentrations of fat-soluble vitamins (A, D3, and E), and total antioxidant status (TAS) were determined. It was shown that the breed of cow, production system, and season significantly influenced the levels of the analysed vitamins in the milk, thus determining its antioxidant status. A significantly richer source of lipophilic vitamins, regardless of the breed of cow, was milk obtained in the spring/summer season (season 2), with statistically significant differences (p≤0.01) found only in the milk of cows from the traditional production system (system I) in which feeding in the spring/summer season was based on the pasture. The higher content of antioxidant vitamins resulted in an increase in the antioxidant potential of the milk. The use of pasture in milk production is, therefore, the optimal way to adapt the composition of milk to the needs of modern consumers while ensuring proper animal welfare. This is also supported by consumers' growing interest in pasture-derived dairy products, as outdoor pasture-based feeding is a natural system for animals.