DETERMINANTS OF FAT CONTENT AND FATTY ACID COMPOSITION IN MILK OF COWS OF DIFFERENT BREEDS. PART 1: EFFECT OF LACTATION PHASE

The aim of the study was to analyze the effect of the lactation phase on the concentration of fat and fatty acids in the milk of cows of three breeds: Polish Red-White (ZR), Polish Red (RP) and Polish Holstein-Friesian Red-White (RW). The study was conducted in 17 herds on a total of 473 cows kept in a traditional barn-pasture. The analyses showed that the milk of RP cows from the 3rd phase of lactation and ZR cows from the 2nd phase of lactation was characterized by the best fatty acid profile – significantly and highly significantly (p < 0.05, p ≤ 0.01) the highest contents of some tested monounsaturated MUFA and polyunsaturated PUFA acids and significantly and highly significantly (p < 0.05, p ≤ 0.01) the lowest contents of some tested SFA acids. Milk with the most expected fat content came from ZR cows from the 1st and 2nd phase of lactation and RW cows from the 1st phase of lactation. RW cows in the 2nd phase of lactation produced milk with the lowest nutritional value – significantly and highly significantly (p < 0.05, p ≤ 0.01) the lowest concentration of some health-promoting MUFA and PUFA acids and significantly and highly significantly (p < 0.05, p ≤ 0.01) the highest concentration of many saturated SFA acids unfavorable for the consumer’s health. RW cows in the 3rd phase of lactation produced milk with the highest fat content. The research results can be used in improving cattle in terms of improving the fatty acid composition of produced milk, and thus improving its health-promoting values.