Foetal sex determination using ultrasonography is being used increasingly on modern-day dairy farms and is now a valuable tool for farm animal veterinary surgeons.  in 1989, Curran et al. described an alternative method of foetal sex determination, which was carried out between days 55 and 65 of pregnancy and involved determining the location of the genital tubercle, a method now known as early foetal sex determination. Lucy Tyler from BCF Technology, explains the advantages and disadvantages of both early and late determination method.