Artificial insemination was the first conceptive technology to be widely used in agriculture. Whereas at the beginning of the twentieth century all cows in England and Wales were mated to bulls, by the end of the 1950s 60% conceived through artificial insemination. By then a national network of ‘cattle breeding centres’ brought AI within the reach of every farmer. In this paper I explore how artificial insemination, which had few supporters in the 1920s and 1930s, was transformed into an ‘indispensable’ (...) method for reproducing cattle. I discuss the factors that made organised AI possible , including changes in cultures of cattle breeding, novel State involvement in bovine reproduction, the rise of new ‘animal breeding research’ centres at Cambridge, Edinburgh and Reading universities, war preparations and central planning by the Milk Marketing Board . I go on to show that the unprecedented focus on bovine reproduction set in motion by the AI centres effectively generated new networks of reproductive research, through these the ‘biopower’ of the farm was incorporated into the clinic. The example of AI shows that by combining the history of reproductive technology in agriculture and medicine we can give a richer account of modern reproduction. (shrink)