The mama hen probably discarded it because it is 'defective' and she wasn't going to spend time and energy on a weak chick. I know that sounds cruel, but chickens do live by the 'survival of the fittest' rule. If you're breeding silkies, you don't want to breed weakness into the flock, so 'saving' that chick is not in your best interest. However, if you're hatching more pets, perhaps a dose of vitamin E and selenium might help? It's hard to say without seeing it move.
On an aside note, a heating pad is a whole lot better than a brooder lamp for broodering chicks in general and for helping sick/injured chicks specifically. A heating pad that does not have auto-shutoff or the auto-shutoff feature can be disabled will keep the chick warm enough without overheating it. It is so easy to overheat a chick with a lamp. Overheating a chick will kill it faster than anything else.
On an aside note, a heating pad is a whole lot better than a brooder lamp for broodering chicks in general and for helping sick/injured chicks specifically. A heating pad that does not have auto-shutoff or the auto-shutoff feature can be disabled will keep the chick warm enough without overheating it. It is so easy to overheat a chick with a lamp. Overheating a chick will kill it faster than anything else.
