Incidence of X-Y aneuploidy in sperm of two indigenous cattle breeds by using dual color fluorescent in situ hybridization (FISH)

The present study reports on the incidence of X-Y aneuploidy in the sperm population of two indigenous cattle breeds reared in Italy for beef purposes, the Podolian and Maremmana. Totally, more than 50 000 sperm nuclei from 10 subjects (5 from each breed) have been fluorescent in situ hybridization (FISH) analyzed by using Xcen- and Y-chromosome-specific painting probes. In both breeds, the fraction of Y-bearing sperm was significantly higher (P < 0.01) compared with the X-counterpart. The rates of X-Y aneuploidy were 0.180% and 0.200%, respectively, in the Podolian and Maremmana. No significant interindividual differences were found. Average frequencies of disomic and diploid sperm were 0.149% and 0.031% in the former and 0.098% and 0.102% in the latter. Significant differences (P < 0.05) were found among the XX-XY and YY-disomy classes in both breeds, while diploidy classes were uniformly represented. In the Podolian breed, disomies were more frequent than diploidies (P < 0.05), whereas in the Maremmana they showed similar frequencies. In both breeds disomies arising from errors in meiosis I (X-Y disomies) were more represented than those arising in meiosis II (XX and YY), while this difference was not detected for diploidies. The present study provides specific information on the incidence of X-Y sperm aneuploidy in two indigenous breeds of cattle, in order to establish a breed-specific 'aneuploidy data-base' that could be used as reference for genetic improvement and future monitoring of the reproductive health of the breed.