EN
126 primigravida of Lowland Red-White cows at the State Pegigree Breeding Centre in Głogówek were studied. The udder measurements were made in the cows periodically /on 10, 100, 200 and 240 day of lactation/. 10 different measurements for each cow in each period were made. The milk yield on the day of measurement, the udder size and udder yield index were measured as well. The cows were divided into 3 groups in order to analyse the effect of the udder shape on the changes in its size during lactation: I - ball-shaped udders, II - box-shaped udders, III - bowl-shaped udders. The cows were also divided into 3 groups with regard to their milk yield during 305 day lactation. The udder size in the first lactation decreased /except for front part depth, the length of teats and the distance from the floor/ irrespective of the shape and milk yield. Absolute values of all the measurements as well as the dynamics of the changes depended mainly on milk yield. The lowest dynamic in the changes was observed in the cows of the highest milk yield. The udders of different types varied during the whole period of studies as far as it concerns the length of udder basis, udder depth and udder width. Bowl-shaped udders showed the slowest rate of changes in length, width and size and the quickest dynamic of changes in depth and front part length during lactation. The changes in other measurement values of all 3 types of udders were similar.