This paper positions the recent emergence of robotic or automatic milking systems (AMS) in relation to discourses surrounding the longer history of milking technologies in the UK and elsewhere. The mechanization of milking has been associated with sets of hopes and anxieties which permeated the transition from hand to increasingly automated forms of milking. This transition has affected the relationships between humans and cows on dairy farms, producing different modes of cow and human agency and subjectivity. In this paper, drawing on empirical evidence from a research project exploring AMS use in contemporary farms, we examine how ongoing debates about the benefits (or otherwise) of AMS relate to longer-term discursive currents surrounding the historical emergence of milking technologies and their implications for efficient farming and the human and bovine experience of milk production. We illustrate how technological change is in part based on understandings of people and cows, at the same time as bovine and human agency and subjectivity are entrained and reconfigured in relation to emerging milking technologies, so that what it is to be a cow or human becomes different as technologies change. We illustrate how this results from – and in – competing ways of understanding cows: as active agents, as contributing to technological design, as ‘free’, as ‘responsible’ and/or requiring surveillance and discipline, and as efficient co-producers, with milking technologies, of milk.