Sperm chromatin integrity and DNA methylation in Norwegian Red bulls of contrasting fertility

In this study, the complexity of chromatin integrity was investigated in frozen-thawed semen samples from 37 sires with contrasting fertility, expressed as 56-day non-return rates (NR56). Protamine deficiency, thiols, and disulfide bonds were assessed compared previously published data for DNA fragmentation index (DFI) high stainability (HDS). addition, vitro embryo development sperm methylation using 16 these bulls. The percentages DFI HDS negatively associated NR56 cleavage rate positively protamine deficiency (p < 0.05). Significant differences blastocyst observed between bulls low NR56. However, once fertilization occurred, further into blastocysts not differential analysis showed that spermatozoa hypermethylated to Pathway genes annotated differentially methylated cytosines could participate different biological pathways have important roles related bull fertility. conclusion, cells Norwegian Red inferior fertility less compact structure, higher levels damage, are superior