CHROMOSOMAL ANEUPLOIDY ASSOCIATED WITH SPONTANEOUS-ABORTIONS AND NEONATAL LOSSES IN CATTLE

Pericardial sac samples from 77 bovine aborted fetuses and stillborn c alves were submitted for tissue culture; cells from 55 of these sample s were grown successfully in culture. Six of the 55 karyotyped fetuses (10.7%) had an abnormal chromosome complement, in 3 of which (5.5%) t he abnormality was probably the cause of death. This level of abnormal ity is relatively high when one considers that most fetuses were >8 mo nths gestational age. Approximately 5-7% of human stillbirths and 50% of first-trimester aborted fetuses have chromosome anomalies. If a sim ilar situation exists in cattle, as suggested by these data, chromosom e abnormalities may be a major cause of early fetal loss in cattle. Mo st chromosomally abnormal fetuses had multiple malformations, which su ggests that the diagnostic use of chromosome analysis is most cost eff ective for malformed fetuses and newborns. Twins were present in a hig her proportion of these fetuses than expected based on their incidence among liveborn cattle.