Forty-five multiparous cows (74-146 d after calving) were blocked into 3 groups of 15 animals on the basis of calving date and milk yield. Within each group the cows were allotted at random to treatment sequences in a 3x3 Latin square design. Cows were fed a ration composed of pasture, maize silage and meadow hay. Treatments were: control (CK), 6 kg concentrate without rolled rape seeds (WRS), MR - 5 kg concentrate and 0.7 kg WRS and HR - 4 kg concentrate and 1.4 kg WRS. The administration of 1.4 kg (HR) rolled rape seeds per cow insignificantly increased the daily milk yield by 1.2 kg and milk fat content. Supplemental fat tended to nonsignificantly decrease the percentage protein content in milk (CK, 3.10, MR, 3.03, HR, 3.04), but the total daily protein production was not affected by treatment. Rolled rape seeds affected the fatty acid composition of milk fat. There was a significant (P<0.05) increase of C 18:1 and C 18:3 content as a result of adding WRS, but no effect on C 18:2 concentration.