Kittens aged 20 days are usually not fully developed enough to defecate on their own. In the wild, kittens are usually stimulated to defecate by their mothers licking their anus. However, if kittens are adopted by humans, they may need to be artificially stimulated to defecate in the early stages, such as by gently massaging their anus with a damp cotton ball or tissue.
As kittens grow, they gradually learn to control their bowel movements and eventually become able to defecate on their own without external stimulation. This process usually occurs when kittens are around one month old. Therefore, if you are caring for a 20-day-old kitten, you may need to continue artificially stimulating its bowel movements until it can handle the problem on its own.
