What is the ruling on slaughtering small male chicks for laying hens due to their lack of economic viability, and feeding them to cats, given that they are not sold and do not produce even half the cost of their upkeep?

There is no harm in slaughtering male chicks to feed people or cats. There is no specific age or appearance of hair required for an animal to be eaten. Giving them to the poor is more preferable than giving them to cats. One is rewarded for feeding cats, which are permissible to own. Islamic law has permitted hunting for the benefit of the game, for eating and selling. If an animal is slaughtered and utilized, even if for feeding cats, there is no harm.