Buddhists Should Be Vegan
I am afraid this will come off as preachy. I don't know how to share this but by saying that I think Buddhists should be Vegan. That is a personal conviction. If you don't share it, please disregard this post.
Many good Buddhists disagree with me. I have no need to convert you to Veganism. I don't look down on those who aren't Vegans. We search are on our own journey. I respect yours, please respect mine.
The First Precept
The first precept, which all Buddhists are supposed to follow, is to "abstain from taking life" (AN 5.179 Thanissaro). That is, we should not kill living creatures, sentient beings.
A "lay follower" is not supposed to do business or trade in "living creatures, meat" (AN 5.177 Sujato). Buddhists should not hunt, fish, or butcher animals. They should not be exterminators. They should not engage in anything that causes animals to suffer and die.
The Buddha said:
Here, a noble disciple, having abandoned the destruction of life, abstains from the destruction of life. By abstaining from the destruction of life, the noble disciple gives to an immeasurable number of beings freedom from fear, enmity, and affliction. He himself in turn enjoys immeasurable freedom from fear, enmity, and affliction (AN 8.39 Bodhi).
Factor farming has made milk, cheese, and eggs a source of untold suffering to animals. You cannot love animals and then paid for their systematic torture and eventual slaughter. Buddhists should be Vegan.
Rebirth
Not only is peace of mind contingent on not harming animals, but so is your future rebirth. The Buddha said that a person who "themselves kill living creatures; they encourage others to kill living creatures; they approve of killing living creatures; and they praise killing living creatures" will be "cast down to hell" (AN 4.264 Sujato). Someone who is "merciless to living beings" will be "deposited in hell (AN 10.212 Bodhi).
The Buddha also said:
some man or woman, abandoning the killing of living beings, abstains from killing living beings; with rod and weapon laid aside, gentle and kindly, he abides compassionate to all living beings. Because of performing and undertaking such action, on the dissolution of the body, after death, he reappears in a happy destination, even in the heavenly world (MN 135 Bodhi)
Vegans go to heaven. The best practice, then, is "where a certain individual himself abstains from the taking of life and encourages others in undertaking abstinence from the taking of life" (AN 4.99 Thanissaro).