They believed an animal had the right to enjoy life before being killed for its meat. They found the idea of killing baby animals for food to be repellent.
This is beautiful. I feel this way too, but broaden the sentiment to include along with longevity, the quality of the animal's life. Chickens should walk around and peck corn and bugs, cows should wander through pastures, etc. I am disgusted by the industrial meat factories that we have developed, where for their entire existence, our meals suffer for the sake of the dollar. Absolutely repugnant.