Can PP cotton be padded in the budgerigar breeding box? Is it okay? Will it form a splayed foot? Is it necessary to pad this with sawdust? Is it harmful to chickens?

No, if you have to pad it, there is a great chance that it will form a splayed foot, making it impossible for colored birds to mate.

In fact, you can directly pad sawdust in the breeding box.

In short, it is not recommended to pad PP cotton in budgerigar breeding boxes.

(You can also put melon seeds or tea leaves in the breeding box. )