Abstract
The mean values and the variances in every year of birth were calculated concerning the 12 parts of the physical characters of the body of 514 Advanced Registry Milk-cows (full-age type) which were born during the 20 years from 1931 to 1950.
All parts of the physical characters of the body indicated the remarkable changes during these 20 years.
Generally speaking, it was recognized that the curve connecting the points of the mean values began to go down in 1933 and showed the lowest points in 1942. Since the year of 1942, the curve began to rise again and continued to rise till 1947.
It kept the same height from that time, but, there occured the phenomena of deterioration in two or three parts.
Further, as to the causes of this change, it may be supposed that they has been due to the various circumstances (mainly fodders and management labours), except the change of hipbones width from 1931 to 1938.
