Against the background of high demand for protein-rich feed in the EU and the environmental degradation associated with intensive livestock farming, insect-based feed is discussed as a potential sustainable alternative to conventional feed. However, the establishment of such an innovation depends not only upon technical and economic feasibility, but also on social factors impacting acceptability. The aim of this paper was to determine the acceptability of different social actor groups towards the use of insects as livestock feed, and to gain (...) insights into value-based arguments leading to positive or negative attitudes and perceived benefits and risks. By means of qualitative content analysis, we analysed responses of an EU public consultation process linked to the authorization of insect protein in pig and poultry feed. We found a broad range of value-based arguments that influence the complex judgement process of acceptability that have been neglected in prior quantitative surveys. In particular, our results bring forward more critical voices, such as animal welfare concerns and scepticism that insect-based feed can contribute to a more sustainable livestock system. Based on these findings, we discuss whether insects as feed are a viable contribution to a sustainability-oriented transformation of the agri-food system. We conclude that under certain conditions (when raised on low-value organic side streams such as manure) insect-based livestock feed may contribute to incremental sustainability improvements. Overall, however, the innovation has limitations, not only in terms of regulatory conditions but especially with regard to ethical concerns. (shrink)