DETERMINANTS OF FAT CONTENT AND FATTY ACID COMPOSITION IN MILK OF COWS OF DIFFERENT BREEDS. PART 2: EFFECT OF COWS’ AGE

The aim of the study was to analyze the effect of cows’ age on the fat content and fatty acid profile in milk of cows of three breeds: Polish Red-White (ZR), Polish Red (RP) and Polish Holstein-Friesian Red-White (RW). The study included 473 cows kept on 17 farms. The cows studied were of different ages, this is in 1st, 2nd, 3rd, ≥4th lactation. Milk samples were collected from each cow during a test milking. The study showed that the milk of younger cows (1st–3rd lactation) of the RP breed and older cows (≥4th lactation) of the ZR breed was characterized by the most favorable fatty acid profile. In the milk fat of both groups of cows, significantly (p < 0.05) and highly significantly (p < 0.01) the highest contents of many of the tested monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were found, as well as highly significantly (p < 0.01) the lowest concentration of some of the tested saturated fatty acids SFA. Milk from RW cows (regardless of the age of the animals) was the milk with the lowest nutritional value in terms of fatty acid composition – significantly (p < 0.05) and highly significantly (p < 0.01) the lowest concentration of many health-promoting MUFA and PUFA acids and significantly (p < 0.05) and highly significantly (p < 0.01) the highest content of some SFA acids that are unfavourable to the health of consumers. The lowest fat concentration was determined in the milk of older cows from the ZR breed (≥4th lactation), while the highest fat concentration was noted in the milk of younger cows from the RP breed (1st–3rd lactation). The obtained results provide important information on the health-promoting values of milk produced by cows of the three breeds studied. Moreover, they can become valuable information for both raw milk producers and consumers of so-called functional food.