Dairy cows provide a spectacular example of what can be achieved with purposeful breeding of nonhuman animals in terms of increasing production and bodily adaptation to particular production systems. This implies that humans can make nonhuman bodies take whatever form they desire. However, the assumption that breeding outcomes are entirely shaped by humans has been criticized. This article contributes to ongoing discussions of breeds as socially constructed and applies a focus on cattle actions. Within a more-than-human biopower framework, cattle actions and ways of “doing” cattle are integral to both the notion and the future of the breed. This ethnography of breeding Swedish Mountain Cattle provides a detailed account of the mutual subjectification of cattle and farmers within an agricultural context, revealing the scope and limits of cattle agency and how “doing” cattle affects individuals and populations.