Why did Dagda carry 2 pigs with him at all times?
Short Answer… Dagda was going to eat them.
Dagda was one of the most important gods in Celtic mythology and was often said to be on par with the Norse God Odin, Greek Zeus and other father gods in various mythologies. His importance in the pantheon was much greater than what the Christian missionaries who came to the region propagated.
The Dagda, who is regarded as a highly esteemed figure, is typically depicted as a peasant-like warrior who doesn’t have much good manners. In post Christian era his representation was changed to that of a pot bellied drunken dishevelled person from what he was originally known for.
He is known to carry 4 treasures in his person at all times that were mainly meant to satisfy his hunger and of the people around him. Apart from a cauldron and a fruit tree, it included 2 pigs. One which was always growing and ready to be killed and the other was always roasting on a spit fire. This ensured that food was always available at any point in time.
These elements prompted the later Christians to belittle Dagda by referring to him as a fat, lazy and gluttonous individual who was dishevelled and not very bright. This depiction was meant to wean the local Celts away from worshipping the Dagda and adopting the Christian mode of worship.