"Coffee shop owners were completely unaware and shocked that their spacecakes are not animal friendly," said a spokeswoman for Dutch animal rights group Wakker Dier, campaigning against the use of eggs from chickens kept caged on battery farms.
Four large shops have switched to free-range eggs and 20 more plan to follow, she said. The shops get through hundreds of eggs a week for their spacecakes, which are baked with marijuana or hashish and can give an intense high.
The coffee shops, where marijuana can be smoked openly in a relaxed atmosphere, are one of Amsterdam's big tourist draws.
Soft drugs are officially banned in the Netherlands but under a policy of tolerance, buyers are allowed to have less than 5 grams of cannabis in their possession.