Paternal determinants of early embryo development

Existing research has primarily focused on investigating the impacts of the maternal environment, female fertility phenotype, and genetics on pregnancy loss in dairy cattle. Recently, attention has been directed toward understanding the role the sire has on embryo quality and viability. Studies have shown there is a paternal influence on early pregnancy loss, but the specific mechanisms impacting pregnancy establishment and maintenance remain unclear. Despite clear differences that sires have on pregnancy outcomes, there is a lack of evidence regarding specifically how sires influence pregnancy. Sperm characteristics, such as motility, concentration, and morphology, have been extensively studied, but further research is needed to understand what makes one sire more or less fertile than another sire and how this affects pregnancy. To effectively address pregnancy loss, a deeper understanding of the processes involved from fertilisation to blastocyst formation is essential, particularly for understanding early pregnancy loss. Sire characteristics can influence several events during fertilisation and preimplantation development including the binding of a spermatozoon to the oocyte, oocyte activation, paternal chromatin remodelling, centriole function, degradation of paternal mitochondria, and regulation of gene expression in the embryo through microRNAs. Defects in any of these processes can hinder embryonic development and lead to pregnancy loss. Some candidate genes have been associated with sire fertility, however, a comprehensive genetic predictor for sire fertility is yet to be fully elucidated. Image created with Biorender.