Question: Would you say that reciting Om Mani Padme Hung is similar to the practice of metta meditation in that it develops loving-kindness and compassion?
Answer: A friend’s wife, at the end of an Om Mani Padme Hum retreat, turned vegetarian upon hearing the heartfelt advice of Drubwang Rinpoche: http://moonpointer.
For some, e.g. those who lack faith in the mantra, metta meditation is more effective, depending on one’s affinity. To know which suits you better, give some time for practice of both and see which leads to greater and substantial rise of compassion.
Becoming vegetarian is a good gauge of a real irreversible change in compassion, because it involves lifelong commitment (though there can be lessening of eating of animals over time; instead of instant results). One who continually wishes to save all beings (nurture Bodhicitta), wishes them to be well and happy, should not at the same time wish to eat some beings every day. It’s a direct conflict of interests – for the ideal of Bodhicitta, and for the animals who die due to demand. This is why vegetarianism is a Bodhisattva precept in the Brahma Net Sutra.
Chanting the mantra is after all to nurture compassion for all beings, including animals, who do us no harm. Metta meditation, is for nurturing unconditional metta for all beings (mother sentient beings), including animals, even if they do not help us in discernible ways.
Related Article:
Bad Faith to Animals
http://moonpointer.com/index.php?itemid=1485