Effects of complex vertebral malformation on fertility traits in Holstein cattle

Previous studies have indicated that the viability of bovine foetuses affected by complex vertebral malformation (CVM) is reduced. To study this a data analysis was performed. Breeding data on Holstein cows being daughters of confirmed CVM carriers and inseminated first time after calving with semen of a sire with established CVM status (normal or carrier) were used. A total of 62602 inseminations were included. The analysis demonstrated that several fertility traits, defined as non-return rates for cows, frequency of calvings after first insemination and interval from insemination to next calving, were significantly affected by a foetal CVM phenotype. Non-return to service rates were severely reduced. Data on calvings 260–300 days after first insemination demonstrated that 77% of the CVM-affected foetuses were aborted prior to gestation day 260. A foetal CVM phenotype increased the maternal risk of being culled.