Anapanasati and Compassion

I'm wondering basically whether anapanasati can *result* in as much compassion as metta. Though the focus is different, **can these two meditations have the same potential for altruism? Does meditating on the breath produce as much compassion?** Basically, I wonder if -- in order to become altruistic and compassionate -- one has to *focus* on compassion as a subject, or if that is not necessary. Thank you