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 embry o viability. Karyotypes were successfully completed on cells from 77 o f the 279 embryos prepared for such analysis. Embryos from 4 cows hete rozygous for the translocation were studied. Two bulls with the same c ondition 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 tr anslocation and those with normal karyotypes, indicating that fertiliz ation rates were not affected: by the translocation. Twenty-two percen t of the embryos which were karyotyped had an unbalanced karyotype and would theoretically not have survived to term. All of the theoretical ly predicted chromosome complements from such a translocation were obs erved as were three 58,XX,t karyotypes and a 58,XX karyotype. There wa s no difference in the percentage of embryos with abnormal karyotypes whether the cow or bull was the carrier. Results therefore indicate th at fertility is rather severely impaired in carriers of the 14;20 tran slocation, as was observed with the 1;29 translocation, with most loss due to embryo mortality rather than a lowered conception rate. (C) 19 97 by Elsevier Science Inc.