The effective altruism movement has produced rigorous analysis of how to maximise welfare impact per pound donated, with farm animal welfare emerging as among the highest-impact areas.
Applying effective altruism principles to animal welfare produces counterintuitive conclusions about impact. Individual animal welfare choices - veganism, rescue adoption - benefit specific animals but have limited systemic impact. Institutional advocacy that changes the practices of large food companies or governments affects millions or billions of animals simultaneously. This scale difference is why effective altruism analysis directs resources toward corporate and policy campaigning over individual behaviour change, and toward farm animals (numerically dominant) over companion animals (welfare systems already much more developed). The effective altruism approach to animal welfare is not coldly calculating - it is motivated by the recognition that scale of impact matters when animals are suffering in very large numbers.