Chromosome fragility in river buffalo cows exposed to dioxin

Fifty river buffalo (Bubalus bubalis, 2n=50) cows reared in two different provinces of Campania (southern Italy) underwent cytogenetic investigations to ascertain possible differences in their chromosome stability. One group (Caserta province) was under legal sequestration due to the presence in the milk mass of higher mean values of dioxins [21.79 pg/g of fat as sum of polychloro-dibenzo-dioxins (PCDDs), polychloro-dibenzo-furans (PCDFs) and dioxinlike polychlorobiphenyls (DL-PCBs)] than both those permitted (6.0 pg/g of fat asWHO-TEQ) and those (1.3 pg/g of fat as WHO-TEQ) observed in the control group raised in Salerno province. Two types of peripheral blood cell cultures were performed: without (normal cultures for the chromosome abnormality (CA) test: chromatid breaks, chromosome breaks, fragments) and with the addition of BrdU for the sister chromatid exchange (SCE) test). The CA test revealed a significantly (P<0.01) higher chromosome fragility in the exposed cows compared to the control. Indeed, mean values of CA/cell were 1.26±1.15 in exposed cows and 0.37±0.71 in the control.Mean SCE was higher in exposed cows (8.50±3.35) than that (8.29± 3.51) found in the control but the difference was not significant. Comparison within the same group of cows at first (FL) and multiple (ML) lactations revealed significantly (P<0.01) higher mean values of CA/cell in exposed ML-cows vs FL-cows while no statistical differences were found between ML-cows and FLcows in the control farm. By contrast, significantly (P<0.01) higher mean values of SCE were found in both groups of FLcows versus ML-cows. Comparisons with other previous studied species (sheep and cattle) were also performed.