It is not a good idea to set up birds for breeding until they are old enough. In captivity, they tend to become sexually mature before they are actually mature enough to successfully breed. Young birds make mistakes with incubation and often fail to feed any chicks that hatch. Young hens are also at a higher risk of becoming egg bound. Wait until they are about three years old to set them up for breeding.
You mentioned they are in one room – are these birds all together in once cage? If so, they could be damaging each other’s feathers. For breeding, they each need a large flight with only one pair per flight. To keep each pair focused, you should have visual barriers between each flight or they will try to compete with the neighboring pair.
Their environment may be too dry, so you might need to get a humidifier as they need a balance for eggs to hatch. If it is too dry or too humid, the eggs will not hatch.
As to diet, it is good they enjoy their Nutri-Berries. These are actually nutritionally balanced as a complete diet and can be fed along with your CHOP mix. Your birds may be over supplemented. I don’t think the vitamin supplement is necessary if they are getting other fortified foods. The Nutri-Berries are balanced the same as a pellet, but they are not ground up. They can be fed along with pellets, or alone. But you really do not need a vitamin supplement also.
If they do not get access to sunlight, you might look into full spectrum lighting, but not as the only light source. Full spectrum lighting needs to be limited to a few hours each day. Again, too much can cause issues just like over supplementing their diet.
Lastly, before you start breeding this many birds, make sure you have someplace for the offspring to go, as they can’t remain with the adults. Indian Ringnecks can be bred in several color mutations and are very pretty. However they are not always good pets and are often aloof and hand shy, even when hand fed. If kept too long after weaning, they can revert to being wild and be hard to find a home for them.
Thank you for asking Lafeber,