Cattle and sheep breeders in the UK and elsewhere increasingly draw on genetic techniques in order to make breeding decisions. Many breeders support such techniques, while others argue against them for a variety of reasons, including their preference for the ‘traditions' of visual-based and pedigree-based selections. Meanwhile, even for those institutions and breeders who promote genetic techniques, the outcomes are not always as predicted. We build on our recent use of Foucault's discussions of biopower to examine the effects of the introduction of genetic techniques in UK livestock breeding in order to begin to explore the diffuse and capillary nature of resistance within relations of biopower. We focus specifically on how resistance and contestation can be understood through the joint lenses of biopower and an understanding of livestock breeding as knowledge-practices enacted within heterogeneous biosocial collectivities. In some instances these collectivities coalesce around shared endeavour, such as increasing the valency of genetic evaluation within livestock breeding. Yet such mixed collectivities also open up opportunities for counter-conduct: heterogeneous resistances to and contestations of genetic evaluation as something represented as progressive and inevitable. We focus on exploring such modes of resistance using detailed empirical research with livestock breeders and breeding institutions. We demonstrate how in different and specific ways geneticisation becomes problematised, and is contested and made more complex, through the knowledge-practices of breeders, the bodies of animals, and the complex relationships between different institutions in livestock breeding and rearing.