Abstract
The aim of the study was to assess the nutritional value and technological parameters of milk produced in organic and conventional farming systems, taking into account the breeds of cow, feeding system, and season of production in Poland. A total of 413 milk samples were analysed, of which 220 were from Simmental cows raised on organic farms and 193 were from conventional farms, including 64 from Polish Black-and-White cows fed in a traditional system, as well as 65 from Simmental cows and 64 from Holstein-Friesian cows fed in a TMR (Total Mixed Ration) system. The milk was analysed for content of fat, protein, lactose, and urea; somatic cell count; suitability for processing (active and titratable acidity, casein content, protein-to-fat ratio, heat stability, and rennet coagulation); and content of biologically active substances (whey proteins, fatty acids, and macro- and microelements). Simmental cows from organic farms had the lowest daily milk yield, with the lowest concentrations of basic nutrients. However, it was a richer source of α-lactalbumin, lactoferrin and lysozyme and had the highest content of PUFA s. It also had a favourable protein-to-fat ratio and the shortest rennet clotting time, but it contained less Ca, Mg and Zn than milk from farms using a TMR system. The season of production had a greater influence on the composition, nutritional value and technological parameters of milk from farms using traditional feeding, including organic farms, compared to those using a TMR diet. Milk from organic farms obtained in the summer season contained more dry matter, including total protein, β-lactoglobulin, α-lactalbumin, lactoferrin, and lysozyme. It was also characterised by a more preferable fatty acid profile, i.e. lower content of SFA and higher of UFA, including MUFA and PUFA . In turn, milk from the winter season contained more fat and showed better heat stability. At farms using traditional feeding regimens, both organic and conventional, the production period had a more significant impact on the differentiation of the content of mineral components in milk (mainly macroelements).