Modern livestock breeding is basically dependent on the proper use of semen for artificial insemination (AI) of females and of other reproductive biotechnologies such as the production of embryos in vitro for embryo transfer (IVP). Both these techniques have made possible not only the wide dissemination of genetic material onto breeding populations but also enhanced the selection of best sires, owing to the development of better diagnostic techniques for sperm function and of preservation of seminal material over time. Although use of liquid semen cooled to room temperature, to intermediate temperatures (+16-20°C) or chilled (+5°C) dominates in different species, cryopreservation is preferred in bovine AI and it is advancing in other species by the design of new containers, freezing methods and the use of better insemination strategies. Techniques to separate the aliquot of most robust spermatozoa from an ejaculate have shown a renascent particularly for sires with low sperm quality, and technological advances in separating spermatozoa for chromosomal sex make the technique suitable for commercial use, following application of novel findings in sperm and seminal plasma (SP) diagnostics and function. Alongside, knowledge of the epigenome and signalling capabilities of the semen (sperm and SP) calls for further studies regarding transgene production via ICSI for IVP or AI