Seeds can be harmful to their intestines since they can't really break them down, also they need more fats during winter. What i feed mine during winter is Purina layena ( pellets and crumbles) and as a treat twice or so a week I mix that in with corn ( cracked and whole) and cat food
How are seeds bad for them?? What do u think they lived on before being domesticated?? Grains and different vegitation. All grain get broke down in the gizzard and crop. Mibe eat Acorns, Corn, Soybeans, Peanuts and oats all the time. In the winter all they will eat is whole grains and a little bit of layer. Other wise they will go without eating.