Any issues with feeding Swans/Duck/Geese wild bird seed

[DMF235-Belfast]

Hello all, just wanted to check on feeding wild water birds, the garden feeding is going fine at the moment. Basically I've long since stopped feeding them white bread and generally feed them the seedier brown breads. So couple of questions, ive got a cheap mixed seed from PAH which seem to have a fair amount of cerals in them and some Red Band Seed, is there anything in them that i'd need to worry about?

I will be checking with one or two pet stores about spexific cracked corn, maze, barely but just wanted to check in the meantime...the pellets seem quite dear

Also if they are feed cabbage/spinach does it need to be boiled? seems daft question to me but one site mentioned it.

Cheers