However, beyond not breaking the first precept, could vegetarianism be used as a practice of developing compassion (karuna) and being compassionate?
Or does the practice of compassion require direct intention and direct action in allaying the sufferings of others, and indirect means are not relevant?
Bhikkhu Khantipalo defined compassion (karuna) here as:
Compassion (karuna) is taking note of the sufferings of other beings in the world. It overcomes callous indifference to the plight of suffering beings, human or otherwise. Likewise, it must be reflected in one's life by a willingness to go out of one's way to give aid where possible, and to help those in distress. It has the advantage of reducing one's selfishness by understanding others' sorrows. It is Lord Buddha's medicine for cruelty, for how can one harm others when one has seen how much they have to suffer already? It has also two enemies: the "near" one is mere grief; while its "far" enemy is cruelty.