Impact of seasonality, storage of semen, and sperm head-shape on whole tissue methylation and expression of methylation responsive candidate genes in swine placenta and fetal livers from summer and winter breedings.

Epigenetics includes the study of external factors that can influence the expression of genes by altering the accessibility of DNA through methylation. To investigate the epigenetic influence of season, sperm head shape, and semen storage on placental and fetal tissues, pregnancies were generated in the summer or winter using boar semen from either least or most sperm head shape change, collected during cool or warm seasons, and stored as cooled-extended or cryopreserved. The lowest (p < 0.

Scrotal insulation and sperm production in the boar.

Seasonal infertility is a limiting factor in boar fertility, and is increasingly important as climate changes. Spermatogenesis in the boar produces 256 spermatozoa per type A spermatogonium, but the process is inefficient such that only 10-30% of these potential spermatozoa are actually produced. Heat further impacts spermatogenesis by reducing the number of specific germ cells produced while increasing the fraction of abnormal sperm.