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 cause of fertility reduction or sterility in domestic animals. While a bulk of papers report about possible environmental and genetic causes of increased incidence of sperm aneuploidy in fertile and infertile man, very few efforts have been directed to characterize the different domestic animal species, breeds and genetic types. The present study aimed to investigate the frequency of X-Y chromosomes aneuploidy in two important Italian autochthonous cattle breeds, the Podolian and Maremmana. Totally, more than 50.000 sperm nuclei from ten subjects (five from each breed) have been FISH analyzed by using Xcen and Y chromosome specific painting probes. Average frequencies of disomic and diploid sperm were 0.150% and 0.032% in the Podolian and 0.099% and 0.102% in the Maremmana. No significant interindividual differences were found. However, significant differences (P<0.05) were found among the three different 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 work contributes to increase the knowledge on the variability in the frequency of sperm aneuploidy in different breeds of cattle, in order to establish a breed specific 'aneuploidy database' that could be used as reference for future monitoring of the reproductive health of the breed.