Fertility effects of the 14;20 Robertsonian translocation in cattle

Superovulation and embryo collection procedures were used to study the effect of the 14;20 Robertsonian translocation on fertility and embryo viability. Karyotypes were successfully completed on cells from 77 of the 279 embryos prepared for such analysis. Embryos from 4 cows heterozygous for the translocation were studied. Two bulls with the same condition were studied by using their semen in artificial insemination of cows with normal karyotypes. The proportions of fertilized ova and transferable embryos were not different between cows with the 14;20 translocation and those with normal karyotypes, indicating that fertilization rates were not affected by the translocation. Twenty-two percent of the embryos which were karyotyped had an unbalanced karyotype and would theoretically not have survived to term. All of the theoretically predicted chromosome complements from such a translocation were observed as were three 58,XX,t karyotypes and a 58,XX karyotype. There was no difference in the percentage of embryos with abnormal karyotypes whether the cow or bull was the carrier. Results therefore indicate that fertility is rather severely impaired in carriers of the 14;20 translocation, as was observed with the 1;29 translocation, with most loss due to embryo mortality rather than a lowered conception rate.