1.The expression probably began because seeds fed to chickens made people think of small change.
feed to 用…喂…;向…提供…;向(某人)提供(情报、信息等):
Farmers feed hay to the cows.
农民用干草喂牛 。
Reporters all over the world feed the news to the TV stations.
遍布世界各地的记者们向电视台提供新闻 。