This article critically explores Foucauldian approaches to the human-animal-technology nexus central to modern industrialised agriculture, in particular those which draw upon Foucault’s conception of power as productive to posit the reconstitution of animal subjectivities in relation to changing agricultural technologies. This is situated in the context of key recent literature addressing animals and biopolitics, and worked through a historical case study of an emergent dairy technology. On this basis it is argued that such approaches contain important insights but also involve risks for the analyses of human-animal-technology relations, especially the risk of subsuming what is irreducible in animal subjectivity and agency under the shaping power of technologies conceived as disciplinary or biopolitical apparatuses. It is argued that this can be avoided by bringing biopolitical analysis into dialogue with currents from actor-network theory in order to trace the formation of biopolitical collectives as heterogeneous assemblages. Drawing upon documentary archive sources, the article explores this by working these different framings of biopolitics through a historical case study of the development of the first mechanical milking machines for use on dairy farms.