Sister-chromatid exchanges in cattle: breed, sex and BrdU dose effects.

The spontaneous incidence of sister-chromatid exchanges (SCE) was investigated in a group of cattle, composed of 21 animals of both sexes and from two different breeds (Fleckvieh and Pirenaica). Peripheral lymphocytes of these animals were cultured in three different bromodeoxyuridine (BrdU) concentrations: 5, 15 and 30 micrograms/ml. The work was carried out following a randomized block design. Among the analyzed sources of variability, group, breed and BrdU dose factors had significant effects on the SCE frequency. No differences between sexes were found. Comparisons of the BdrU doses showed that the 5 micrograms/ml dose differed from both the 15 and 30 micrograms/ml doses, whereas the 15 and 30 micrograms/ml doses did not differ from each other. The results indicate that the breed of cattle as well as the BrdU dose chosen for the analysis must be considered when the SCE test is used for the biomonitoring of environmental mutagens.