What would happen if we change to an opt-out scheme and there is still a shortage of organs? If that happens society may decide to use pig organs - I hope it doesn't - but if it does we must ensure there is no increase in the number of animals used for human purposes. This means we will have to cut back on some other use of animals - in the case of pigs that means eating less meat.
I'm standing in the middle of a pig shed. To my left and right, I see row after row of tightly packed sows and their squealing piglets. The building is a sorry sight - hard, featureless, sometimes barely visible in the dim light. I want to leave, except I'm not actually "there". Welcome to the curious world of virtual reality.
Imagine being a pig on a typical farm in Europe. Most likely you'll have nothing to do but stare at your fellow pen mates and four concrete walls whilst you stand on a slatted floor. Shockingly, the European Commission thinks that keeping pigs in barren environments on slatted floors is the 'Best Available Technique' for the environment.