non-Hay fodder crops

Does anybody raise root crops, melons, or pumpkins for winter fodder? I am especially interested in mangles. I read somewhere that they have to be stored till the first of January, because they are slightly poisonous till then. Also, that traditional English farmers said that they greatly increased milk production, and they can give a huge yield per acre.

Also, does anybody plant poisonous medicinal plants in their pastures, like Sepp does? If so, how does it work?