Food waste is collected and fed to the pigs.
Wow. So which law is it we'd be breaking if we did that in the UK? I always assumed it was an EU directive that we'd adopted?
You can feed some types of food waste to pigs and people do widely - bread, spent malt, fruit and veg, etc. You and the supplier just have to be registered appropriately. It is stuff that has been through a kitchen that can't be used.
According to an article in Country Smallholding (Spring 2018):
"following the outbreak of foot and mouth disease in 2001, the UK Government banned the feeding of all catering waste. This was in case it might contain - or come into contact with - contaminated animal by-products. The ruling was subsequently extended by the EU to all member states".
So, the rules were started by the UK, are the same in Spain as here.