What is the ruling on "tadyir" of camels (forcing a she-camel to suckle other than her offspring), knowing that the process is painful for the she-camel?

There is no legal impediment to compelling a she-camel or other animals to accept a young that is not their own (training/taming) if there is a benefit in it, provided that the animal is not tormented if training can be achieved without it. This is because tormenting an animal is impermissible except for an overwhelming benefit and to the extent of the need. It has been authentically reported from the Prophet, peace and blessings be upon him, that he permitted some actions that might be understood as torment but were for a benefit, such as his sacrifice of two castrated rams and the branding of charity camels.