I've never given our chickens whole kernel corn, we do throw scratch, which has cracked corn in it, into the run sometimes. I think the whole kernels would be hard to digest especially for young chickens.
Dry rice isn't actually good for them. I highly recommend chick feed and if you supplement you can choose nutritious options, those could even be safe (non toxic for chickens) weeds!
I'm no expert, but I have to agree with the others. White dry rice has almost no nutritional value beyond carbohydrates. I also doubt that the pigeon food has enough protein for healthy development.
Is it not possible to purchase commercial chick starter where you live? Are you letting your chicks spend all day outdoors to scratch for insects? Do they have green plants to eat where you have them during the day? Could you at least get a hold of sunflower seeds and whole grains that you could grind up?