A vegetarian excluded any meat-based foods from their diets, either as a personal choice or as part of their culture. They were not to be confused with herbivores, whose natural diet consisted solely of plant-based foods.
Spock was described as a herbivore once, in TAS: "The Slaver Weapon". In VOY: "Flashback", Tuvok eats (seemingly non-replicated) Porakan eggs. By some definitions, eggs are not vegetarian. The Vulcan propensity for vegetarianism was mentioned in the first draft script of ENT: "Shadows of P'Jem" (written while the episode had the working title "Untitled Andorians Return"), wherein CommanderTucker commented to Vulcan CaptainSopek, "For a bunch vegetarians, you people can be awfully trigger happy." In the final edit of the episode, the reference to vegetarianism is omitted, Tucker instead remarking to Sopek, "You're awfully trigger happy for someone who's repressed his emotions."
The preference for keeping live animals by the Human colonists on Omicron Ceti III a century before the eradication of farming on Earth suggests the practice was abandoned sometime between those two points.