Podstawowy skład chemiczny i zawartość składników mineralnych w mleku krów różnych ras użytkowanych w gospodarstwach ekologicznych i konwencjonalnych z intensywnym i tradycyjnym systemem żywienia

The aim of study was to evaluate the chemical composition, including mineral content, in milk of different breeds maintained in organic and traditional farms using intensive (PMR) and traditional feeding systems. The study was carried out on 47 farms in south-eastern Poland. A total of 735 milk samples were analysed, including 263 from cows raised on organic farms, 218 from cows raised on conventional farms using a traditional feeding system, and 254 from cows raised on conventional farms using an intensive feeding system (PMR). All types of farms raised Polish Holstein-Friesian and Simmental cows, and the conventional farms using a traditional feeding system also kept Polish Red and White-Backed cows. The highest (p ≤ 0.01) daily milk yield and content of protein, lactose, dry matter and urea in the milk were obtained from the cows fed in the PMR system. The highest fat content was noted for the milk from the conventional farms using a traditional feeding system. The animals raised in the organic system produced the least milk, with the lowest concentrations of its basic nutrients. The highest mineral content was noted for the milk from the traditional system. The milk from the organic system contained the least Ca, Na, Mg, Zn and Fe, while the milk from the intensive system contained the least Mn. The content of Cu was similar in the milk from the organic and intensive systems and lower (p ≤ 0.01) than in the milk from the traditional system. The results of two-way analysis of variance indicate that the breed of cow significantly influenced milk yield, protein content, protein-to-fat ratio, Ca and Zn concentration (p ≤ 0.01), and the content of dry matter, Fe and Mn in the milk (p ≤ 0.05).