Abstract: Complex vertebral malformation is caused by a single base mutation from G to T at the nucleotide position 559 in the bovine solute carrier family 35 member 3 (SLC35A3) gene exon 4 on Bos Taurus autosome (BTA) 3. The presence of the disease gene in Holstein dairy cattle has been reported in many countries. In this study, we examined 38 top Chinese Holstein sires in Beijing, four of which were identified as CVM carriers. Furthermore, 555 daughters of the four CV sires were examined and 44.0% of them were identified as heterozygotes at the mutation site. The association analysis between estimated breeding values (EBV) of dairy performance traits and the polymorphism showed that there were extremely sig-nificant differences between the carriers and the non-carriers (P<0.01). The EBVs of the five milk production traits of CVM carriers were significantly higher than those of non-carriers, and the lactation persistency and somatic cell score (SCS) were also higher in CVM carriers. Therefore, CVM gene seems to link with a QTL or gene associated with milk production traits on BTA3. It is recommended to cull the CVM carriers gradually for economical and breeding reasons.

Key words: Chinese Holstein, primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR), complex vertebral malformation (CVM), SLC35A3 gene, association analysis