Incidence and inheritance of the 1/29 and 14/20 Robertsonian translocations in Canadian beef cattle.

Metaphase chromosomes were prepared from peripheral leukocyte cultures of 253 beef animals representing 21 breeds. A total of 10 Robertsonian translocations were identified. Nine were 1/29 fusions and one was a stable 14/20 fusion identified in several Simmentals. To our knowledge, the only other case of this translocation reported was also in the Simmental breed, suggesting that this fusion may be unique to the breed. A further 54 relatives of known 1/29 and 14/20 carriers were examined, revealing that both fusions were inherited by 50% of offspring of the heterozygous carrier. Heterozygous male 1/29 carriers left fewer calves than karyotypically normal bulls when used in natural service.