Giving : Not Taking
If there is no meat eater, there will be no animal killer.
One of the greatest obstacles to the birth of Bodhicitta in our minds is our craving for meat.
- Shabkar Tsogdruk Rangdrol
(Food of Bodhisattvas: Buddhist Teachings on Abstaining from Meat)
The Buddha as a Bodhisattva in the Jataka Tales is a perfect example of practising the perfection of giving (generosity) - often giving His life to benefit or even feed others. Meat-eating by choice, is obviously the opposite, as it demands (even if indirectly by the supply-demand loop) to feed on others. It is the taking (antithesis of giving) of the dearest to living beings - their lives. He could not bear to see an animal eat another animal. Likewise, he will not do the unbearable - to eat any animal.
In this sense, I see the most basic aspect of the perfection of giving being the giving of harmlessness. Before a practising Bodhisattva thinks of taking his meal, s/he should think of giving other beings a break from his/her dining table. This is simply a small but important part of the practice of compassion.