COMPARISON OF LIPID-COMPOSITION OF MILK FROM HALF-DANISH JERSEY COWS AND UNITED-STATES JERSEY COWS

We studied differences in lipid composition of milk from Jersey cows with US sires and from Jersey cows with Danish sires. Milk samples were obtained on DHIA test day from 32 cows with Danish sires and 32 herdmates with US sires in two herds, The Jerseys with US sires were paired with those with Danish sires by parity and stage of lactation. Mean percentage of milk fat was 5.7% for Jerseys with Danish sires and 4.8% for Jerseys with US sires, Total fat per day was the same (.91 kg) for both groups. Detailed analysis of milk lipids indicated that lipid composition of milk was similar for cows with US sires and those with Danish sires, However, milk from Jerseys with Danish sires contained more free cholesterol than milk from Jerseys with US sires, 17.5 versus 14.3 +/- .6 mg/dl. The proportion of polyunsaturated fatty acids was greater for milk from Jerseys with US sires than for milk from Jerseys with Danish sires (2.3 vs. 2.1%). Although lipid composition of milk from both groups was generally similar, the milk of Jersey cows with Danish sires had higher concentrations of free cholesterol and lower proportions of polyunsaturated fatty acids, both of which are possible negative factors for health of consumers.