I believe that an egg is only an animal by product if it is not fit for human consumption, (check DEFRAS advice)therefore your pigs may enjoy them, probably best straight from the shed in case there is a query about them having been in the kitchen
. If it was true that eggs per se are animal by products then it is also illegal to feed them to the dog/cat any pet. Of course we all ensure our dogs eat no forbidden animal by products! Meg I fear is ill disciplined enjoying a range of poo and lately lambing extras.