Parakeets and Cockatiels are seed eaters in the wild. They often do not accept pellets very well. But loose seeds are usually not very fresh and have lost most of their nutrients, plus any added vitamins are lost when they hull the seeds.
I would recommend that you try them on Nutri-Berries and/or Avi-Cakes. These contain fresh, hulled seeds combined with other ingredients to provide complete nutrition. They are nutritionally balanced the same as a pellet, but they are not ground up. You can feed these and know your birds are getting the nutrition they need. But you need to stop offering additional seeds once they learn how to eat the Nutri-Berries or Avi-Cakes. As far as fresh foods, it’s good if they will eat them, but as long as they are getting a nutritionally balanced food, it is not going to hurt them if they flat refuse to eat any. Try offering leafy greens or broccoli florets. Sometimes it can take a while for a bird to accept a new food, so just keep trying.
Here is a link to our bird food guide:
Bird Food Guide
Thank you for asking Lafeber,