IMO, the lack of food dyes, as well as the lack of pellets (in a seed mix). Also, variety. I don't agree that food dyes should be in a bird food, since it can do more harm than good... worse, it distorts the color of droppings so you can't tell if a dropping appears normal or not. I have yet to come across a good seed mix that includes pellets, thus I refuse to get a mix that has them (those dry things that may look like cerial or otherwise). I also try to go for variety since birds are known for eating a variety of foods, even in the wild.
Is it the ratio of different seeds?
No, rather the variety is what I'm looking for... although the amount of certain seeds does play a bit of a role in choosing which brand...
Does Volkmans have a variety of seed the other do not?
I can't say as I've never used Volkmans...
When I look for a seed mix, I'm looking for something that has variety. I buy Sweet Harvest Cockatiel no/sun seed, which looks like this...
And with this, I mix in with 2 parts, a canary mix... this comes from a "gravity bin" since I can't find any canary mixes I like in bags... the bin top is closed, so I don't really worry much about something getting INTO the mix...
Of course, there's also sprouts (ATM I have two sprout mixes), fresh foods, and pellets (which I put through the food processor).
If you don't think your seed is fresh, sprout it. I heard it's the best way to tell if it's a good seed mix or not. It would mean that the seed is alive (it'll take up to 3 days before you start seeing sprouts), but I'm not necessarily sure it'll mean it's a good mix...
