Deficiency of uridine monophosphate synthase in Holstein cattle: inheritance and body measurements

Blood samples and body measurements were obtained from daughters of seven Holstein bulls previously shown to have a partial deficiency of uridine monophosphate (UMP) synthase and presumed to be heterozygous for the condition. Erythrocyte UMP synthase for 85 daughters showed a bimodal distribution with 42 having half the normal activity of 43 others. Furthermore, each bull had 50% of his daughters represented in each group, a finding fully consistent with the heterozygous designation of these bulls. Because UMP synthase is needed for pyrimidine biosynthesis and hence DNA and RNA metabolism, it was hypothesized that a partial deficiency could result in slower growth and smaller size for affected animals. Body measurements, as estimates of growth and size, included body length, wither height, hip height, hip width, rump length, pin width and taped body weight. Although measurements varied by age, differences between normal and heterozygous females were not found. One-half the normal activity of UMP synthase in cattle was adequate for near normal growth. Additionally, herd life was not significantly affected in heterozygous females.