Chromosome fragility in freemartin cattle.

The aim of the present study was to verify chromosome fragility in freemartin cattle using chromosome aberration (CA) and sister chromatid exchange (SCE) tests. A total of eighteen co-twins were investigated.Fourteen animals were identified as cytogenetically chimeric (2n=60, XX/XY) while 4 were classified as normal.Freemartin cattle showed a higher percentage of aneuploid cells (18.64%) and highly significant statistical differences (P < 0.001) in mean values of gaps (4.53 ± 2.05), chromatid breaks (0.26 ± 0.51), and significant statistical differences (P < 0.005) in mean values of chromosome breaks (0.12 ± 0.43) when compared to 10 control animals from single births(aneuploid cells, 11.20%; gaps, 2.01 ± 1.42; chromatid breaks, 0.05 ± 0.22; chromosome breaks, 0.02 ± 0.14).