X Y aneuploidy rates in sperm of the Maremmana and Podolian cattle breeds by using dual-color fluorescent in situ hybridization (FISH)

Sex chromosomes aneuploidies are a common causeof fertility reduction or sterility in domestic animals.While a bulk of papers report about possibleenvironmental and genetic causes of increased incidenceof sperm aneuploidy in fertile and infertile man,very few efforts have been directed to characterize thedifferent domestic animal species, breeds and genetictypes. The present study aimed to investigate thefrequency of X-Y chromosomes aneuploidy in twoimportant Italian autochthonous cattle breeds, thePodolian and Maremmana. Totally, more than50.000 sperm nuclei from ten subjects (five fromeach breed) have been FISH analyzed by using Xcenand Y chromosome specific painting probes. Averagefrequencies of disomic and diploid sperm were0.150% and 0.032% in the Podolian and 0.099%and 0.102% in the Maremmana. No significantinterindividual differences were found. However,significant differences (P<0.05) were found amongthe three different disomy classes in both breeds,while diploidy classes were uniformly represented. Inthe Podolian breed, disomies were more frequent thandiploidies (P<0.05), whereas in the Maremmana theyshowed similar frequencies. In both breeds disomiesarising from errors in meiosis I (X-Y disomies) weremore represented than those arising in meiosis II (XXand YY), while this difference was not detected fordiploidies. The present work contributes to increasethe knowledge on the variability in the frequency ofsperm aneuploidy in different breeds of cattle, inorder to establish a breed specific 'aneuploidy database'that could be used as reference for futuremonitoring of the reproductive health of the breed.