Testing for deficiency of uridine monophosphate synthase among holstein-friesian cattle of North America and Europe

Abstract

The deficiency of uridine monophosphate (UMP) synthase is an autosomal recessive disorder in Holstein-Friesian cattle that is lethal in the early embryonic period. In late 1987, the condition was declared an undesirable enzyme defect by the Holstein Association of America and testing programs were initiated, whereby heterozygotes were detected by half normal activity of erythrocyte UMP synthase. From January 1988 through December 1991, 3461 animals were tested in North America, with 585 carriers identified. In the same period, 1226 were tested in Europe, with 414 carriers detected. More carriers for this condition have been identified than for any other inherited disorder in Holstein-Friesian cattle. The testing programs uncovered carriers in a blood-line without a close relationship to previously identified carriers. The testing results confirmed the age-dependence for erythrocyte UMP synthase among normal and heterozygous animals. The number of animals tested peaked in 1989 and has decreased since then; such a profile should be expected for inherited disorders in domesticated animals when an efficient testing program is instituted. Testing permits identification of carriers, their removal from the breeding population, decreased frequency of the condition and consequently reduced need for further testing. However, elite animals of a breed should continue to be monitored to ensure that a disorder does not reappear.