DNA methylation biomarkers of fertility in bulls

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Fertility in dairy cows has become a real concern despite the progression made in genetic selection to alleviate this phenotype. One of the possible explanations for the increased prevalence of mild infertility could be the epigenetic programming that would act in addition to genetic programming. The molecular basis for epigenetic effect is the stability of DNA methylation which is transmitted from cells to cells through replication. We are actually one of the few research groups in the world with extensive expertise in bovine DNA methylation analysis which could be used to study gene-environment interaction and the potential impact on the next generation. It is now well demonstrated in rodents, sheep and cows that the phenomena may impact the next generation fertility. It is also well demonstrated in mammals that the male environment can influence the phenotype of the offspring. Therefore, the hypothesis is that metabolically stressed females could generate bulls with a particular epigenome in their testis resulting in either a direct effect on the sperm impairing fertility or affected embryos resulting in a modified phenotype in the daughter. To screen for such epitome, it would be important to compare a relatively high number of bulls but removing the individual variations associated with individuals. To achieve such a task, we will analyze sperm samples from 100 bulls according to 2 phenotypes, bull's fertility and daughter's fertility which could identify intergenerational biomarkers associated with the phenotype. Bulls will be contrasted using a new DNA capture approach followed by sequencing to identify DNA methylation changes according to phenotypes. Then pyrosequencing will be used to validate specific biomarkers associated with fertility. These markers will then be tested. on blood and hair instead of cement to test a diagnostic potential at birth.