I feed egg and biscuit to my canarys when they are breeding. Particularly if there is not a lot of seeding grass round at the time, the gouldians seem to like it too. Don't overfeed so no problems with fat finches.
LML
I used to use egg biscuit dry mix for my canaries found that the finches weren't to keen, now I boil 4 eggs cut them in half and give half each to a flight then once the half is gone I put in two halves, found that the birds devoured it all finches as well. Have done the boiled egg and arrowroot biscuit mix found that in summer I would get maybe 4 hours before it turned, much easier to throw what's left of an egg instead of having to clean containers.
Nathan
Alot of birds really like egg and biscuit mix,some may take time to get the taste. E/B can be a very good addition to the birds diet
but you must realise too much is not good for some of the species we keep.
Just remember feed in moderation so birds won't get too fat and don't leave the mix in the sun or out too long especially during the summer.
Each has personal theories and ideas but remember its the egg that has all the food value in it.