The field of genetic improvement of the cattle population represents 'big money' business, as well as fascinating science. The ease with which both semen and embryos can be frozen and transported has led to extensive international exchanges of material between widely separated geographical areas such as the USA, Canada, the UK, the rest of Europe and Australia. Many genes in British Friesian herds, for example, have been replaced by those from American Holsteins.

This section has important links with core syllabus content material relating to reproduction in humans.