Totalism states that one population is better than another iff it has higher total welfare. One counterintuitive consequence is the Repugnant Conclusion (RC). Totalism also entails that a very large population of animals with lives barely worth living is better than a smaller population of happier humans. Furthermore, the strategies that have been used to avoid the troubling normative implications of the RC do not work in the animal case, so we may have reason to bring about such a population. (...) I introduce the notion of ‘Efficiency of Welfare Production’ – that animals of different species vary in the efficiency with which they convert resources into welfare. If we want to maximize total welfare, without any speciesist bias, we should identify which species is most efficient and try to maximize the population of that species. This has counterintuitive implications whether we accept hedonism or a more sophisticated theory of welfare. (shrink)